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x86 candidate patches for review II: 64bit relocatable kernel

PATCH In review Andi Kleen 9 participants 202 messages Apr 28, 2007 – May 10, 2007

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#2 lore raw

PATCH 2/22 x86_64: Assembly safe page.h and pgtable.h

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

This patch makes pgtable.h and page.h safe to include in assembly files like head.S. Allowing us to use symbolic constants instead of hard coded numbers when refering to the page tables.

This patch copies asm-sparc64/const.h to asm-x86_64 to get a definition of _AC() a very convinient macro that allows us to force the type when we are compiling the code in C and to drop all of the type information when we are using the constant in assembly. Previously this was done with multiple definition of the same constant. const.h was modified slightly so that it works when given CONFIG options as arguments.

This patch adds #ifndef __ASSEMBLY__ ... #endif and _AC(1,UL) where appropriate so the assembler won't choke on the header files. Otherwise nothing should have changed.

AK: added const.h to exported headers to fix headers_check

---

 include/asm-x86_64/Kbuild    |    1 +
 include/asm-x86_64/const.h   |   20 ++++++++++++++++++++
 include/asm-x86_64/page.h    |   28 ++++++++++------------------
 include/asm-x86_64/pgtable.h |   33 +++++++++++++++++++++------------
 4 files changed, 52 insertions(+), 30 deletions(-)
include/asm-x86_64/const.h new file +20 -0
Index: linux/include/asm-x86_64/const.h
===================================================================
@@ -0,0 +1,20 @@
+/* const.h: Macros for dealing with constants.  */
+
+#ifndef _X86_64_CONST_H
+#define _X86_64_CONST_H
+
+/* Some constant macros are used in both assembler and
+ * C code.  Therefore we cannot annotate them always with
+ * 'UL' and other type specificers unilaterally.  We
+ * use the following macros to deal with this.
+ */
+
+#ifdef __ASSEMBLY__
+#define _AC(X,Y)	X
+#else
+#define __AC(X,Y)	(X##Y)
+#define _AC(X,Y)	__AC(X,Y)
+#endif
+
+
+#endif /* !(_X86_64_CONST_H) */
include/asm-x86_64/page.h +10 -18
Index: linux/include/asm-x86_64/page.h
===================================================================
@@ -1,14 +1,11 @@
 #ifndef _X86_64_PAGE_H
 #define _X86_64_PAGE_H
 
+#include <asm/const.h>
 
 /* PAGE_SHIFT determines the page size */
 #define PAGE_SHIFT	12
-#ifdef __ASSEMBLY__
-#define PAGE_SIZE	(0x1 << PAGE_SHIFT)
-#else
-#define PAGE_SIZE	(1UL << PAGE_SHIFT)
-#endif
+#define PAGE_SIZE	(_AC(1,UL) << PAGE_SHIFT)
 #define PAGE_MASK	(~(PAGE_SIZE-1))
 #define PHYSICAL_PAGE_MASK	(~(PAGE_SIZE-1) & __PHYSICAL_MASK)
 
@@ -33,10 +30,10 @@
 #define N_EXCEPTION_STACKS 5  /* hw limit: 7 */
 
 #define LARGE_PAGE_MASK (~(LARGE_PAGE_SIZE-1))
-#define LARGE_PAGE_SIZE (1UL << PMD_SHIFT)
+#define LARGE_PAGE_SIZE (_AC(1,UL) << PMD_SHIFT)
 
 #define HPAGE_SHIFT PMD_SHIFT
-#define HPAGE_SIZE	((1UL) << HPAGE_SHIFT)
+#define HPAGE_SIZE	(_AC(1,UL) << HPAGE_SHIFT)
 #define HPAGE_MASK	(~(HPAGE_SIZE - 1))
 #define HUGETLB_PAGE_ORDER	(HPAGE_SHIFT - PAGE_SHIFT)
 
@@ -76,29 +73,24 @@ typedef struct { unsigned long pgprot; }
 #define __pgd(x) ((pgd_t) { (x) } )
 #define __pgprot(x)	((pgprot_t) { (x) } )
 
-#define __PHYSICAL_START	((unsigned long)CONFIG_PHYSICAL_START)
-#define __START_KERNEL		(__START_KERNEL_map + __PHYSICAL_START)
-#define __START_KERNEL_map	0xffffffff80000000UL
-#define __PAGE_OFFSET           0xffff810000000000UL
+#endif /* !__ASSEMBLY__ */
 
-#else
 #define __PHYSICAL_START	CONFIG_PHYSICAL_START
 #define __START_KERNEL		(__START_KERNEL_map + __PHYSICAL_START)
 #define __START_KERNEL_map	0xffffffff80000000
 #define __PAGE_OFFSET           0xffff810000000000
-#endif /* !__ASSEMBLY__ */
 
 /* to align the pointer to the (next) page boundary */
 #define PAGE_ALIGN(addr)	(((addr)+PAGE_SIZE-1)&PAGE_MASK)
 
 /* See Documentation/x86_64/mm.txt for a description of the memory map. */
 #define __PHYSICAL_MASK_SHIFT	46
-#define __PHYSICAL_MASK		((1UL << __PHYSICAL_MASK_SHIFT) - 1)
+#define __PHYSICAL_MASK		((_AC(1,UL) << __PHYSICAL_MASK_SHIFT) - 1)
 #define __VIRTUAL_MASK_SHIFT	48
-#define __VIRTUAL_MASK		((1UL << __VIRTUAL_MASK_SHIFT) - 1)
+#define __VIRTUAL_MASK		((_AC(1,UL) << __VIRTUAL_MASK_SHIFT) - 1)
 
-#define KERNEL_TEXT_SIZE  (40UL*1024*1024)
-#define KERNEL_TEXT_START 0xffffffff80000000UL 
+#define KERNEL_TEXT_SIZE  (40*1024*1024)
+#define KERNEL_TEXT_START 0xffffffff80000000
 
 #ifndef __ASSEMBLY__
 
@@ -106,7 +98,7 @@ typedef struct { unsigned long pgprot; }
 
 #endif /* __ASSEMBLY__ */
 
-#define PAGE_OFFSET		((unsigned long)__PAGE_OFFSET)
+#define PAGE_OFFSET		__PAGE_OFFSET
 
 /* Note: __pa(&symbol_visible_to_c) should be always replaced with __pa_symbol.
    Otherwise you risk miscompilation. */ 
include/asm-x86_64/pgtable.h +21 -12
Index: linux/include/asm-x86_64/pgtable.h
===================================================================
@@ -1,6 +1,9 @@
 #ifndef _X86_64_PGTABLE_H
 #define _X86_64_PGTABLE_H
 
+#include <asm/const.h>
+#ifndef __ASSEMBLY__
+
 /*
  * This file contains the functions and defines necessary to modify and use
  * the x86-64 page table tree.
@@ -30,6 +33,8 @@ extern void clear_kernel_mapping(unsigne
 extern unsigned long empty_zero_page[PAGE_SIZE/sizeof(unsigned long)];
 #define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
 
+#endif /* !__ASSEMBLY__ */
+
 /*
  * PGDIR_SHIFT determines what a top-level page table entry can map
  */
@@ -54,6 +59,8 @@ extern unsigned long empty_zero_page[PAG
  */
 #define PTRS_PER_PTE	512
 
+#ifndef __ASSEMBLY__
+
 #define pte_ERROR(e) \
 	printk("%s:%d: bad pte %p(%016lx).\n", __FILE__, __LINE__, &(e), pte_val(e))
 #define pmd_ERROR(e) \
@@ -117,22 +124,23 @@ static inline pte_t ptep_get_and_clear_f
 
 #define pte_pgprot(a)	(__pgprot((a).pte & ~PHYSICAL_PAGE_MASK))
 
-#define PMD_SIZE	(1UL << PMD_SHIFT)
+#endif /* !__ASSEMBLY__ */
+
+#define PMD_SIZE	(_AC(1,UL) << PMD_SHIFT)
 #define PMD_MASK	(~(PMD_SIZE-1))
-#define PUD_SIZE	(1UL << PUD_SHIFT)
+#define PUD_SIZE	(_AC(1,UL) << PUD_SHIFT)
 #define PUD_MASK	(~(PUD_SIZE-1))
-#define PGDIR_SIZE	(1UL << PGDIR_SHIFT)
+#define PGDIR_SIZE	(_AC(1,UL) << PGDIR_SHIFT)
 #define PGDIR_MASK	(~(PGDIR_SIZE-1))
 
 #define USER_PTRS_PER_PGD	((TASK_SIZE-1)/PGDIR_SIZE+1)
 #define FIRST_USER_ADDRESS	0
 
-#ifndef __ASSEMBLY__
-#define MAXMEM		 0x3fffffffffffUL
-#define VMALLOC_START    0xffffc20000000000UL
-#define VMALLOC_END      0xffffe1ffffffffffUL
-#define MODULES_VADDR    0xffffffff88000000UL
-#define MODULES_END      0xfffffffffff00000UL
+#define MAXMEM		 0x3fffffffffff
+#define VMALLOC_START    0xffffc20000000000
+#define VMALLOC_END      0xffffe1ffffffffff
+#define MODULES_VADDR    0xffffffff88000000
+#define MODULES_END      0xfffffffffff00000
 #define MODULES_LEN   (MODULES_END - MODULES_VADDR)
 
 #define _PAGE_BIT_PRESENT	0
@@ -158,7 +166,7 @@ static inline pte_t ptep_get_and_clear_f
 #define _PAGE_GLOBAL	0x100	/* Global TLB entry */
 
 #define _PAGE_PROTNONE	0x080	/* If not present */
-#define _PAGE_NX        (1UL<<_PAGE_BIT_NX)
+#define _PAGE_NX        (_AC(1,UL)<<_PAGE_BIT_NX)
 
 #define _PAGE_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED | _PAGE_DIRTY)
 #define _KERNPG_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
@@ -220,6 +228,8 @@ static inline pte_t ptep_get_and_clear_f
 #define __S110	PAGE_SHARED_EXEC
 #define __S111	PAGE_SHARED_EXEC
 
+#ifndef __ASSEMBLY__
+
 static inline unsigned long pgd_bad(pgd_t pgd)
 {
 	return pgd_val(pgd) & ~(PTE_MASK | _KERNPG_TABLE | _PAGE_USER);
@@ -405,8 +415,6 @@ extern spinlock_t pgd_lock;
 extern struct page *pgd_list;
 void vmalloc_sync_all(void);
 
-#endif /* !__ASSEMBLY__ */
-
 extern int kern_addr_valid(unsigned long addr); 
 
 #define io_remap_pfn_range(vma, vaddr, pfn, size, prot)		\
@@ -436,5 +444,6 @@ extern int kern_addr_valid(unsigned long
 #define __HAVE_ARCH_PTEP_SET_WRPROTECT
 #define __HAVE_ARCH_PTE_SAME
 #include <asm-generic/pgtable.h>
+#endif /* !__ASSEMBLY__ */
 
 #endif /* _X86_64_PGTABLE_H */
include/asm-x86_64/Kbuild +1 -0
Index: linux/include/asm-x86_64/Kbuild
===================================================================
@@ -18,3 +18,4 @@ header-y += vsyscall32.h
 unifdef-y += mce.h
 unifdef-y += mtrr.h
 unifdef-y += vsyscall.h
+unifdef-y += const.h
author
#3 lore raw

PATCH 3/22 x86_64: Kill temp boot pmds

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

Early in the boot process we need the ability to set up temporary mappings, before our normal mechanisms are initialized. Currently this is used to map pages that are part of the page tables we are building and pages during the dmi scan.

The core problem is that we are using the user portion of the page tables to implement this. Which means that while this mechanism is active we cannot catch NULL pointer dereferences and we deviate from the normal ways of handling things.

In this patch I modify early_ioremap to map pages into the kernel portion of address space, roughly where we will later put modules, and I make the discovery of which addresses we can use dynamic which removes all kinds of static limits and remove the dependencies on implementation details between different parts of the code.

Now alloc_low_page() and unmap_low_page() use early_iomap() and early_iounmap() to allocate/map and unmap a page.

---

 arch/x86_64/kernel/head.S |    3 -
 arch/x86_64/mm/init.c     |  100 ++++++++++++++++++++--------------------------
 2 files changed, 45 insertions(+), 58 deletions(-)
arch/x86_64/kernel/head.S +0 -3
Index: linux/arch/x86_64/kernel/head.S
===================================================================
@@ -288,9 +288,6 @@ NEXT_PAGE(level2_ident_pgt)
 	.quad	i << 21 | 0x083
 	i = i + 1
 	.endr
-	/* Temporary mappings for the super early allocator in arch/x86_64/mm/init.c */
-	.globl temp_boot_pmds
-temp_boot_pmds:
 	.fill	492,8,0
 	
 NEXT_PAGE(level2_kernel_pgt)
arch/x86_64/mm/init.c +45 -55

165 lines not on this page · raw message

author
#10 lore raw

PATCH 10/22 x86_64: Get rid of dead code in suspend resume

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

o Get rid of dead code in wakeup.S

o We never restore from saved_gdt, saved_idt, saved_ltd, saved_tss, saved_cr3, saved_cr4, saved_cr0, real_save_gdt, saved_efer, saved_efer2. Get rid of of associated code.

o Get rid of bogus_magic, bogus_31_magic and bogus_magic2. No longer being used.

---

 arch/x86_64/kernel/acpi/wakeup.S |   57 ---------------------------------------
 1 file changed, 1 insertion(+), 56 deletions(-)
arch/x86_64/kernel/acpi/wakeup.S +1 -56
Index: linux/arch/x86_64/kernel/acpi/wakeup.S
===================================================================
@@ -258,8 +258,6 @@ gdt_48a:
 	.word	0, 0				# gdt base (filled in later)
 	
 	
-real_save_gdt:	.word 0
-		.quad 0
 real_magic:	.quad 0
 video_mode:	.quad 0
 video_flags:	.quad 0
@@ -272,10 +270,6 @@ bogus_32_magic:
 	movb	$0xb3,%al	;  outb %al,$0x80
 	jmp bogus_32_magic
 
-bogus_31_magic:
-	movb	$0xb1,%al	;  outb %al,$0x80
-	jmp bogus_31_magic
-
 bogus_cpu:
 	movb	$0xbc,%al	;  outb %al,$0x80
 	jmp bogus_cpu
@@ -346,16 +340,6 @@ check_vesaa:
 
 _setbada: jmp setbada
 
-	.code64
-bogus_magic:
-	movw	$0x0e00 + 'B', %ds:(0xb8018)
-	jmp bogus_magic
-
-bogus_magic2:
-	movw	$0x0e00 + '2', %ds:(0xb8018)
-	jmp bogus_magic2
-	
-
 wakeup_stack_begin:	# Stack grows down
 
 .org	0xff0
@@ -373,28 +357,11 @@ ENTRY(wakeup_end)
 #
 # Returned address is location of code in low memory (past data and stack)
 #
+	.code64
 ENTRY(acpi_copy_wakeup_routine)
 	pushq	%rax
-	pushq	%rcx
 	pushq	%rdx
 
-	sgdt	saved_gdt
-	sidt	saved_idt
-	sldt	saved_ldt
-	str	saved_tss
-
-	movq    %cr3, %rdx
-	movq    %rdx, saved_cr3
-	movq    %cr4, %rdx
-	movq    %rdx, saved_cr4
-	movq	%cr0, %rdx
-	movq	%rdx, saved_cr0
-	sgdt    real_save_gdt - wakeup_start (,%rdi)
-	movl	$MSR_EFER, %ecx
-	rdmsr
-	movl	%eax, saved_efer
-	movl	%edx, saved_efer2
-
 	movl	saved_video_mode, %edx
 	movl	%edx, video_mode - wakeup_start (,%rdi)
 	movl	acpi_video_flags, %edx
@@ -407,17 +374,8 @@ ENTRY(acpi_copy_wakeup_routine)
 	cmpl	$0x9abcdef0, %eax
 	jne	bogus_32_magic
 
-	# make sure %cr4 is set correctly (features, etc)
-	movl	saved_cr4 - __START_KERNEL_map, %eax
-	movq	%rax, %cr4
-
-	movl	saved_cr0 - __START_KERNEL_map, %eax
-	movq	%rax, %cr0
-	jmp	1f		# Flush pipelines
-1:
 	# restore the regs we used
 	popq	%rdx
-	popq	%rcx
 	popq	%rax
 ENTRY(do_suspend_lowlevel_s4bios)
 	ret
@@ -512,16 +470,3 @@ ENTRY(saved_eip)	.quad	0
 ENTRY(saved_esp)	.quad	0
 
 ENTRY(saved_magic)	.quad	0
-
-ALIGN
-# saved registers
-saved_gdt:	.quad	0,0
-saved_idt:	.quad	0,0
-saved_ldt:	.quad	0
-saved_tss:	.quad	0
-
-saved_cr0:	.quad 0
-saved_cr3:	.quad 0
-saved_cr4:	.quad 0
-saved_efer:	.quad 0
-saved_efer2:	.quad 0
author
#7 lore raw

PATCH 7/22 x86_64: cleanup segments

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

Move __KERNEL32_CS up into the unused gdt entry. __KERNEL32_CS is used when entering the kernel so putting it first is useful when trying to keep boot gdt sizes to a minimum.

Set the accessed bit on all gdt entries. We don't care so there is no need for the cpu to burn the extra cycles, and it potentially allows the pages to be immutable. Plus it is confusing when debugging and your gdt entries mysteriously change.

---

 arch/x86_64/kernel/head.S    |   12 ++++++------
 include/asm-x86_64/segment.h |    2 +-
 2 files changed, 7 insertions(+), 7 deletions(-)
arch/x86_64/kernel/head.S +6 -6
Index: linux/arch/x86_64/kernel/head.S
===================================================================
@@ -362,13 +362,13 @@ gdt:
 	
 ENTRY(cpu_gdt_table)
 	.quad	0x0000000000000000	/* NULL descriptor */
+	.quad	0x00cf9b000000ffff	/* __KERNEL32_CS */
+	.quad	0x00af9b000000ffff	/* __KERNEL_CS */
+	.quad	0x00cf93000000ffff	/* __KERNEL_DS */
+	.quad	0x00cffb000000ffff	/* __USER32_CS */
+	.quad	0x00cff3000000ffff	/* __USER_DS, __USER32_DS  */
+	.quad	0x00affb000000ffff	/* __USER_CS */
 	.quad	0x0			/* unused */
-	.quad	0x00af9a000000ffff	/* __KERNEL_CS */
-	.quad	0x00cf92000000ffff	/* __KERNEL_DS */
-	.quad	0x00cffa000000ffff	/* __USER32_CS */
-	.quad	0x00cff2000000ffff	/* __USER_DS, __USER32_DS  */		
-	.quad	0x00affa000000ffff	/* __USER_CS */
-	.quad	0x00cf9a000000ffff	/* __KERNEL32_CS */
 	.quad	0,0			/* TSS */
 	.quad	0,0			/* LDT */
 	.quad   0,0,0			/* three TLS descriptors */ 
include/asm-x86_64/segment.h +1 -1
Index: linux/include/asm-x86_64/segment.h
===================================================================
@@ -6,7 +6,7 @@
 #define __KERNEL_CS	0x10
 #define __KERNEL_DS	0x18
 
-#define __KERNEL32_CS   0x38
+#define __KERNEL32_CS   0x08
 
 /* 
  * we cannot use the same code segment descriptor for user and kernel

Andi Kleen

author
#0 lore raw

cover x86 candidate patches for review II: 64bit relocatable kernel

Here are the patches to support the relocatable kernel on x86-64. All done by Eric Biederman and Vivek Goyal. Following i386. Also includes lots of cleanup to various boot paths.

Vivek already posted them a couple of time.

Please review.

-Andi

author
#1 lore raw

PATCH 1/22 x86_64: dma_ops as const

From: Stephen Hemminger <[email protected]> The dma_ops structure can be const since it never changes after boot.

---
 arch/x86_64/kernel/pci-calgary.c |    2 +-
 arch/x86_64/kernel/pci-gart.c    |    2 +-
 arch/x86_64/kernel/pci-nommu.c   |    2 +-
 arch/x86_64/kernel/pci-swiotlb.c |    2 +-
 arch/x86_64/mm/init.c            |    2 +-
 include/asm-x86_64/dma-mapping.h |    2 +-
 6 files changed, 6 insertions(+), 6 deletions(-)
arch/x86_64/kernel/pci-calgary.c +1 -1
Index: linux/arch/x86_64/kernel/pci-calgary.c
===================================================================
@@ -507,7 +507,7 @@ error:
 	return ret;
 }
 
-static struct dma_mapping_ops calgary_dma_ops = {
+static const struct dma_mapping_ops calgary_dma_ops = {
 	.alloc_coherent = calgary_alloc_coherent,
 	.map_single = calgary_map_single,
 	.unmap_single = calgary_unmap_single,
arch/x86_64/kernel/pci-gart.c +1 -1
Index: linux/arch/x86_64/kernel/pci-gart.c
===================================================================
@@ -556,7 +556,7 @@ static __init int init_k8_gatt(struct ag
 
 extern int agp_amd64_init(void);
 
-static struct dma_mapping_ops gart_dma_ops = {
+static const struct dma_mapping_ops gart_dma_ops = {
 	.mapping_error = NULL,
 	.map_single = gart_map_single,
 	.map_simple = gart_map_simple,
arch/x86_64/kernel/pci-nommu.c +1 -1
Index: linux/arch/x86_64/kernel/pci-nommu.c
===================================================================
@@ -79,7 +79,7 @@ void nommu_unmap_sg(struct device *dev, 
 {
 }
 
-struct dma_mapping_ops nommu_dma_ops = {
+const struct dma_mapping_ops nommu_dma_ops = {
 	.map_single = nommu_map_single,
 	.unmap_single = nommu_unmap_single,
 	.map_sg = nommu_map_sg,
arch/x86_64/kernel/pci-swiotlb.c +1 -1
Index: linux/arch/x86_64/kernel/pci-swiotlb.c
===================================================================
@@ -12,7 +12,7 @@
 int swiotlb __read_mostly;
 EXPORT_SYMBOL(swiotlb);
 
-struct dma_mapping_ops swiotlb_dma_ops = {
+const struct dma_mapping_ops swiotlb_dma_ops = {
 	.mapping_error = swiotlb_dma_mapping_error,
 	.alloc_coherent = swiotlb_alloc_coherent,
 	.free_coherent = swiotlb_free_coherent,
arch/x86_64/mm/init.c +1 -1
Index: linux/arch/x86_64/mm/init.c
===================================================================
@@ -46,7 +46,7 @@
 #define Dprintk(x...)
 #endif
 
-struct dma_mapping_ops* dma_ops;
+const struct dma_mapping_ops* dma_ops;
 EXPORT_SYMBOL(dma_ops);
 
 static unsigned long dma_reserve __initdata;
include/asm-x86_64/dma-mapping.h +1 -1
Index: linux/include/asm-x86_64/dma-mapping.h
===================================================================
@@ -52,7 +52,7 @@ struct dma_mapping_ops {
 };
 
 extern dma_addr_t bad_dma_address;
-extern struct dma_mapping_ops* dma_ops;
+extern const struct dma_mapping_ops* dma_ops;
 extern int iommu_merge;
 
 static inline int dma_mapping_error(dma_addr_t dma_addr)
author
#8 lore raw

PATCH 8/22 x86_64: Add EFER to the register set saved by save_processor_state

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

EFER varies like %cr4 depending on the cpu capabilities, and which cpu capabilities we want to make use of. So save/restore it make certain we have the same EFER value when we are done.

---

 arch/x86_64/kernel/suspend.c |    3 ++-
 include/asm-x86_64/suspend.h |    1 +
 2 files changed, 3 insertions(+), 1 deletion(-)
arch/x86_64/kernel/suspend.c +2 -1
Index: linux/arch/x86_64/kernel/suspend.c
===================================================================
@@ -33,7 +33,6 @@ void __save_processor_state(struct saved
 	asm volatile ("str %0"  : "=m" (ctxt->tr));
 
 	/* XMM0..XMM15 should be handled by kernel_fpu_begin(). */
-	/* EFER should be constant for kernel version, no need to handle it. */
 	/*
 	 * segment registers
 	 */
@@ -50,6 +49,7 @@ void __save_processor_state(struct saved
 	/*
 	 * control registers 
 	 */
+	rdmsrl(MSR_EFER, ctxt->efer);
 	asm volatile ("movq %%cr0, %0" : "=r" (ctxt->cr0));
 	asm volatile ("movq %%cr2, %0" : "=r" (ctxt->cr2));
 	asm volatile ("movq %%cr3, %0" : "=r" (ctxt->cr3));
@@ -75,6 +75,7 @@ void __restore_processor_state(struct sa
 	/*
 	 * control registers
 	 */
+	wrmsrl(MSR_EFER, ctxt->efer);
 	asm volatile ("movq %0, %%cr8" :: "r" (ctxt->cr8));
 	asm volatile ("movq %0, %%cr4" :: "r" (ctxt->cr4));
 	asm volatile ("movq %0, %%cr3" :: "r" (ctxt->cr3));
include/asm-x86_64/suspend.h +1 -0
Index: linux/include/asm-x86_64/suspend.h
===================================================================
@@ -17,6 +17,7 @@ struct saved_context {
   	u16 ds, es, fs, gs, ss;
 	unsigned long gs_base, gs_kernel_base, fs_base;
 	unsigned long cr0, cr2, cr3, cr4, cr8;
+	unsigned long efer;
 	u16 gdt_pad;
 	u16 gdt_limit;
 	unsigned long gdt_base;
author
#4 lore raw

PATCH 4/22 x86_64: Clean up the early boot page table

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

- Merge physmem_pgt and ident_pgt, removing physmem_pgt. The merge is broken as soon as mm/init.c:init_memory_mapping is run.
- As physmem_pgt is gone don't export it in pgtable.h.
- Use defines from pgtable.h for page permissions.
- Fix the physical memory identity mapping so it is at the correct address.
- Remove the physical memory mapping from wakeup_level4_pgt it is at the wrong address so we can't possibly be usinging it.
- Simply NEXT_PAGE the work to calculate the phys_ alias of the labels was very cool. Unfortuantely it was a brittle special purpose hack that makes maitenance more difficult. Instead just use label - __START_KERNEL_map like we do everywhere else in assembly.

---

 arch/x86_64/kernel/head.S    |   61 +++++++++++++++++++------------------------
 include/asm-x86_64/pgtable.h |    1 
 2 files changed, 28 insertions(+), 34 deletions(-)
arch/x86_64/kernel/head.S +28 -33
Index: linux/arch/x86_64/kernel/head.S
===================================================================
@@ -13,6 +13,7 @@
 #include <linux/init.h>
 #include <asm/desc.h>
 #include <asm/segment.h>
+#include <asm/pgtable.h>
 #include <asm/page.h>
 #include <asm/msr.h>
 #include <asm/cache.h>
@@ -260,52 +261,48 @@ ljumpvector:
 ENTRY(stext)
 ENTRY(_stext)
 
-	$page = 0
 #define NEXT_PAGE(name) \
-	$page = $page + 1; \
-	.org $page * 0x1000; \
-	phys_/**/name = $page * 0x1000 + __PHYSICAL_START; \
+	.balign	PAGE_SIZE; \
 ENTRY(name)
 
+/* Automate the creation of 1 to 1 mapping pmd entries */
+#define PMDS(START, PERM, COUNT)		\
+	i = 0 ;					\
+	.rept (COUNT) ;				\
+	.quad	(START) + (i << 21) + (PERM) ;	\
+	i = i + 1 ;				\
+	.endr
+
 NEXT_PAGE(init_level4_pgt)
 	/* This gets initialized in x86_64_start_kernel */
 	.fill	512,8,0
 
 NEXT_PAGE(level3_ident_pgt)
-	.quad	phys_level2_ident_pgt | 0x007
+	.quad	level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
 	.fill	511,8,0
 
 NEXT_PAGE(level3_kernel_pgt)
 	.fill	510,8,0
 	/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
-	.quad	phys_level2_kernel_pgt | 0x007
+	.quad	level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
 	.fill	1,8,0
 
 NEXT_PAGE(level2_ident_pgt)
-	/* 40MB for bootup. 	*/
-	i = 0
-	.rept 20
-	.quad	i << 21 | 0x083
-	i = i + 1
-	.endr
-	.fill	492,8,0
+	/* Since I easily can, map the first 1G.
+	 * Don't set NX because code runs from these pages.
+	 */
+	PMDS(0x0000000000000000, __PAGE_KERNEL_LARGE_EXEC, PTRS_PER_PMD)
 	
 NEXT_PAGE(level2_kernel_pgt)
 	/* 40MB kernel mapping. The kernel code cannot be bigger than that.
 	   When you change this change KERNEL_TEXT_SIZE in page.h too. */
 	/* (2^48-(2*1024*1024*1024)-((2^39)*511)-((2^30)*510)) = 0 */
-	i = 0
-	.rept 20
-	.quad	i << 21 | 0x183
-	i = i + 1
-	.endr
+	PMDS(0x0000000000000000, __PAGE_KERNEL_LARGE_EXEC|_PAGE_GLOBAL,
+		KERNEL_TEXT_SIZE/PMD_SIZE)
 	/* Module mapping starts here */
-	.fill	492,8,0
-
-NEXT_PAGE(level3_physmem_pgt)
-	.quad	phys_level2_kernel_pgt | 0x007	/* so that __va works even before pagetable_init */
-	.fill	511,8,0
+	.fill	(PTRS_PER_PMD - (KERNEL_TEXT_SIZE/PMD_SIZE)),8,0
 
+#undef PMDS
 #undef NEXT_PAGE
 
 	.data
@@ -313,12 +310,10 @@ NEXT_PAGE(level3_physmem_pgt)
 #ifdef CONFIG_ACPI_SLEEP
 	.align PAGE_SIZE
 ENTRY(wakeup_level4_pgt)
-	.quad	phys_level3_ident_pgt | 0x007
-	.fill	255,8,0
-	.quad	phys_level3_physmem_pgt | 0x007
-	.fill	254,8,0
+	.quad	level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
+	.fill	510,8,0
 	/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
-	.quad	phys_level3_kernel_pgt | 0x007
+	.quad	level3_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
 #endif
 
 #ifndef CONFIG_HOTPLUG_CPU
@@ -332,12 +327,12 @@ ENTRY(wakeup_level4_pgt)
 	 */
 	.align PAGE_SIZE
 ENTRY(boot_level4_pgt)
-	.quad	phys_level3_ident_pgt | 0x007
-	.fill	255,8,0
-	.quad	phys_level3_physmem_pgt | 0x007
-	.fill	254,8,0
+	.quad	level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
+	.fill	257,8,0
+	.quad	level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
+	.fill	252,8,0
 	/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
-	.quad	phys_level3_kernel_pgt | 0x007
+	.quad	level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
 
 	.data
 
include/asm-x86_64/pgtable.h +0 -1
Index: linux/include/asm-x86_64/pgtable.h
===================================================================
@@ -14,7 +14,6 @@
 #include <asm/pda.h>
 
 extern pud_t level3_kernel_pgt[512];
-extern pud_t level3_physmem_pgt[512];
 extern pud_t level3_ident_pgt[512];
 extern pmd_t level2_kernel_pgt[512];
 extern pgd_t init_level4_pgt[];
author
#6 lore raw

PATCH 6/22 x86_64: modify copy_bootdata to use virtual addresses

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

Use virtual addresses instead of physical addresses in copy bootdata. In addition fix the implementation of the old bootloader convention. Everything is at real_mode_data always. It is just that sometimes real_mode_data was relocated by setup.S to not sit at 0x90000.

---

 arch/x86_64/kernel/head64.c |   17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)
arch/x86_64/kernel/head64.c +8 -9
Index: linux/arch/x86_64/kernel/head64.c
===================================================================
@@ -29,25 +29,24 @@ static void __init clear_bss(void)
 }
 
 #define NEW_CL_POINTER		0x228	/* Relative to real mode data */
-#define OLD_CL_MAGIC_ADDR	0x90020
+#define OLD_CL_MAGIC_ADDR	0x20
 #define OLD_CL_MAGIC            0xA33F
-#define OLD_CL_BASE_ADDR        0x90000
-#define OLD_CL_OFFSET           0x90022
+#define OLD_CL_OFFSET           0x22
 
 static void __init copy_bootdata(char *real_mode_data)
 {
-	int new_data;
+	unsigned long new_data;
 	char * command_line;
 
 	memcpy(x86_boot_params, real_mode_data, BOOT_PARAM_SIZE);
-	new_data = *(int *) (x86_boot_params + NEW_CL_POINTER);
+	new_data = *(u32 *) (x86_boot_params + NEW_CL_POINTER);
 	if (!new_data) {
-		if (OLD_CL_MAGIC != * (u16 *) OLD_CL_MAGIC_ADDR) {
+		if (OLD_CL_MAGIC != *(u16 *)(real_mode_data + OLD_CL_MAGIC_ADDR)) {
 			return;
 		}
-		new_data = OLD_CL_BASE_ADDR + * (u16 *) OLD_CL_OFFSET;
+		new_data = __pa(real_mode_data) + *(u16 *)(real_mode_data + OLD_CL_OFFSET);
 	}
-	command_line = (char *) ((u64)(new_data));
+	command_line = __va(new_data);
 	memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
 }
 
@@ -74,7 +73,7 @@ void __init x86_64_start_kernel(char * r
  		cpu_pda(i) = &boot_cpu_pda[i];
 
 	pda_init(0);
-	copy_bootdata(real_mode_data);
+	copy_bootdata(__va(real_mode_data));
 #ifdef CONFIG_SMP
 	cpu_set(0, cpu_online_map);
 #endif
author
#5 lore raw

PATCH 5/22 x86_64: Fix early printk to use standard ISA mapping

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

---

 arch/x86_64/kernel/early_printk.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
arch/x86_64/kernel/early_printk.c +1 -2
Index: linux/arch/x86_64/kernel/early_printk.c
===================================================================
@@ -11,11 +11,10 @@
 
 #ifdef __i386__
 #include <asm/setup.h>
-#define VGABASE		(__ISA_IO_base + 0xb8000)
 #else
 #include <asm/bootsetup.h>
-#define VGABASE		((void __iomem *)0xffffffff800b8000UL)
 #endif
+#define VGABASE		(__ISA_IO_base + 0xb8000)
 
 static int max_ypos = 25, max_xpos = 80;
 static int current_ypos = 25, current_xpos = 0;
author
#13 lore raw

PATCH 13/22 x86_64: 64bit ACPI wakeup trampoline

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

o Moved wakeup_level4_pgt into the wakeup routine so we can run the kernel above 4G.

o Now we first go to 64bit mode and continue to run from trampoline and then then start accessing kernel symbols and restore processor context. This enables us to resume even in relocatable kernel context when kernel might not be loaded at physical addr it has been compiled for.

o Removed the need for modifying any existing kernel page table.

o Increased the size of the wakeup routine to 8K. This is required as wake page tables are on trampoline itself and they got to be at 4K boundary, hence one page is not sufficient.

---

 arch/x86_64/kernel/acpi/sleep.c  |   24 ++-------------
 arch/x86_64/kernel/acpi/wakeup.S |   59 ++++++++++++++++++++++++---------------
 arch/x86_64/kernel/head.S        |    9 -----
 3 files changed, 41 insertions(+), 51 deletions(-)
arch/x86_64/kernel/acpi/sleep.c +4 -20
Index: linux/arch/x86_64/kernel/acpi/sleep.c
===================================================================
@@ -60,19 +60,6 @@ extern char wakeup_start, wakeup_end;
 
 extern unsigned long acpi_copy_wakeup_routine(unsigned long);
 
-static pgd_t low_ptr;
-
-static void init_low_mapping(void)
-{
-	pgd_t *slot0 = pgd_offset(current->mm, 0UL);
-	low_ptr = *slot0;
-	/* FIXME: We're playing with the current task's page tables here, which
-	 * is potentially dangerous on SMP systems.
-	 */
-	set_pgd(slot0, *pgd_offset(current->mm, PAGE_OFFSET));
-	local_flush_tlb();
-}
-
 /**
  * acpi_save_state_mem - save kernel state
  *
@@ -81,8 +68,6 @@ static void init_low_mapping(void)
  */
 int acpi_save_state_mem(void)
 {
-	init_low_mapping();
-
 	memcpy((void *)acpi_wakeup_address, &wakeup_start,
 	       &wakeup_end - &wakeup_start);
 	acpi_copy_wakeup_routine(acpi_wakeup_address);
@@ -95,8 +80,6 @@ int acpi_save_state_mem(void)
  */
 void acpi_restore_state_mem(void)
 {
-	set_pgd(pgd_offset(current->mm, 0UL), low_ptr);
-	local_flush_tlb();
 }
 
 /**
@@ -109,10 +92,11 @@ void acpi_restore_state_mem(void)
  */
 void __init acpi_reserve_bootmem(void)
 {
-	acpi_wakeup_address = (unsigned long)alloc_bootmem_low(PAGE_SIZE);
-	if ((&wakeup_end - &wakeup_start) > PAGE_SIZE)
+	acpi_wakeup_address = (unsigned long)alloc_bootmem_low(PAGE_SIZE*2);
+	if ((&wakeup_end - &wakeup_start) > (PAGE_SIZE*2))
 		printk(KERN_CRIT
-		       "ACPI: Wakeup code way too big, will crash on attempt to suspend\n");
+		       "ACPI: Wakeup code way too big, will crash on attempt"
+		       " to suspend\n");
 }
 
 static int __init acpi_sleep_setup(char *str)
arch/x86_64/kernel/acpi/wakeup.S +37 -22

142 lines not on this page · raw message

arch/x86_64/kernel/head.S +0 -9
Index: linux/arch/x86_64/kernel/head.S
===================================================================
@@ -308,15 +308,6 @@ NEXT_PAGE(level2_kernel_pgt)
 
 	.data
 
-#ifdef CONFIG_ACPI_SLEEP
-	.align PAGE_SIZE
-ENTRY(wakeup_level4_pgt)
-	.quad	level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
-	.fill	510,8,0
-	/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
-	.quad	level3_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE
-#endif
-
 #ifndef CONFIG_HOTPLUG_CPU
 	__INITDATA
 #endif
author
#14 lore raw

PATCH 14/22 x86_64: Modify discover_ebda to use virtual addresses

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

---

 arch/x86_64/kernel/setup.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
arch/x86_64/kernel/setup.c +2 -2
Index: linux/arch/x86_64/kernel/setup.c
===================================================================
@@ -205,10 +205,10 @@ static void discover_ebda(void)
 	 * there is a real-mode segmented pointer pointing to the 
 	 * 4K EBDA area at 0x40E
 	 */
-	ebda_addr = *(unsigned short *)EBDA_ADDR_POINTER;
+	ebda_addr = *(unsigned short *)__va(EBDA_ADDR_POINTER);
 	ebda_addr <<= 4;
 
-	ebda_size = *(unsigned short *)(unsigned long)ebda_addr;
+	ebda_size = *(unsigned short *)__va(ebda_addr);
 
 	/* Round EBDA up to pages */
 	if (ebda_size == 0)
author
#15 lore raw

PATCH 15/22 x86_64: Remove the identity mapping as early as possible

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

With the rewrite of the SMP trampoline and the early page allocator there is nothing that needs identity mapped pages, once we start executing C code.

So add zap_identity_mappings into head64.c and remove zap_low_mappings() from much later in the code. The functions
are subtly different thus the name change.

This also kills boot_level4_pgt which was from an earlier attempt to move the identity mappings as early as possible, and is now no longer needed. Essentially I have replaced boot_level4_pgt with trampoline_level4_pgt in trampoline.S

---

 arch/x86_64/kernel/head.S    |   39 ++++++++++++++-------------------------
 arch/x86_64/kernel/head64.c  |   17 +++++++++++------
 arch/x86_64/kernel/setup.c   |    2 --
 arch/x86_64/kernel/setup64.c |    1 -
 arch/x86_64/mm/init.c        |   24 ------------------------
 include/asm-x86_64/pgtable.h |    1 -
 include/asm-x86_64/proto.h   |    2 --
 7 files changed, 25 insertions(+), 61 deletions(-)
arch/x86_64/kernel/head64.c +11 -6
Index: linux/arch/x86_64/kernel/head64.c
===================================================================
@@ -18,8 +18,16 @@
 #include <asm/setup.h>
 #include <asm/desc.h>
 #include <asm/pgtable.h>
+#include <asm/tlbflush.h>
 #include <asm/sections.h>
 
+static void __init zap_identity_mappings(void)
+{
+	pgd_t *pgd = pgd_offset_k(0UL);
+	pgd_clear(pgd);
+	__flush_tlb();
+}
+
 /* Don't add a printk in there. printk relies on the PDA which is not initialized 
    yet. */
 static void __init clear_bss(void)
@@ -57,18 +65,15 @@ void __init x86_64_start_kernel(char * r
 	/* clear bss before set_intr_gate with early_idt_handler */
 	clear_bss();
 
+	/* Make NULL pointers segfault */
+	zap_identity_mappings();
+
 	for (i = 0; i < IDT_ENTRIES; i++)
 		set_intr_gate(i, early_idt_handler);
 	asm volatile("lidt %0" :: "m" (idt_descr));
 
 	early_printk("Kernel alive\n");
 
-	/*
-	 * switch to init_level4_pgt from boot_level4_pgt
-	 */
-	memcpy(init_level4_pgt, boot_level4_pgt, PTRS_PER_PGD*sizeof(pgd_t));
-	asm volatile("movq %0,%%cr3" :: "r" (__pa_symbol(&init_level4_pgt)));
-
  	for (i = 0; i < NR_CPUS; i++)
  		cpu_pda(i) = &boot_cpu_pda[i];
 
arch/x86_64/kernel/head.S +14 -25
Index: linux/arch/x86_64/kernel/head.S
===================================================================
@@ -71,7 +71,7 @@ startup_32:
 	movl	%eax, %cr4
 
 	/* Setup early boot stage 4 level pagetables */
-	movl	$(boot_level4_pgt - __START_KERNEL_map), %eax
+	movl	$(init_level4_pgt - __START_KERNEL_map), %eax
 	movl	%eax, %cr3
 
 	/* Setup EFER (Extended Feature Enable Register) */
@@ -115,7 +115,7 @@ ENTRY(secondary_startup_64)
 	movq	%rax, %cr4
 
 	/* Setup early boot stage 4 level pagetables. */
-	movq	$(boot_level4_pgt - __START_KERNEL_map), %rax
+	movq	$(init_level4_pgt - __START_KERNEL_map), %rax
 	movq	%rax, %cr3
 
 	/* Check if nx is implemented */
@@ -274,9 +274,19 @@ ENTRY(name)
 	i = i + 1 ;				\
 	.endr
 
+	/*
+	 * This default setting generates an ident mapping at address 0x100000
+	 * and a mapping for the kernel that precisely maps virtual address
+	 * 0xffffffff80000000 to physical address 0x000000. (always using
+	 * 2Mbyte large pages provided by PAE mode)
+	 */
 NEXT_PAGE(init_level4_pgt)
-	/* This gets initialized in x86_64_start_kernel */
-	.fill	512,8,0
+	.quad	level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
+	.fill	257,8,0
+	.quad	level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
+	.fill	252,8,0
+	/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
+	.quad	level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
 
 NEXT_PAGE(level3_ident_pgt)
 	.quad	level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
@@ -307,27 +317,6 @@ NEXT_PAGE(level2_kernel_pgt)
 #undef NEXT_PAGE
 
 	.data
-
-#ifndef CONFIG_HOTPLUG_CPU
-	__INITDATA
-#endif
-	/*
-	 * This default setting generates an ident mapping at address 0x100000
-	 * and a mapping for the kernel that precisely maps virtual address
-	 * 0xffffffff80000000 to physical address 0x000000. (always using
-	 * 2Mbyte large pages provided by PAE mode)
-	 */
-	.align PAGE_SIZE
-ENTRY(boot_level4_pgt)
-	.quad	level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
-	.fill	257,8,0
-	.quad	level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE
-	.fill	252,8,0
-	/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
-	.quad	level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE
-
-	.data
-
 	.align 16
 	.globl cpu_gdt_descr
 cpu_gdt_descr:
arch/x86_64/kernel/setup64.c +0 -1
Index: linux/arch/x86_64/kernel/setup64.c
===================================================================
@@ -201,7 +201,6 @@ void __cpuinit cpu_init (void)
 	/* CPU 0 is initialised in head64.c */
 	if (cpu != 0) {
 		pda_init(cpu);
-		zap_low_mappings(cpu);
 	} else 
 		estacks = boot_exception_stacks; 
 
arch/x86_64/kernel/setup.c +0 -2
Index: linux/arch/x86_64/kernel/setup.c
===================================================================
@@ -274,8 +274,6 @@ void __init setup_arch(char **cmdline_p)
 
 	dmi_scan_machine();
 
-	zap_low_mappings(0);
-
 #ifdef CONFIG_ACPI
 	/*
 	 * Initialize the ACPI boot-time table parser (gets the RSDP and SDT).
arch/x86_64/mm/init.c +0 -24
Index: linux/arch/x86_64/mm/init.c
===================================================================
@@ -378,21 +378,6 @@ void __meminit init_memory_mapping(unsig
 	__flush_tlb_all();
 }
 
-void __cpuinit zap_low_mappings(int cpu)
-{
-	if (cpu == 0) {
-		pgd_t *pgd = pgd_offset_k(0UL);
-		pgd_clear(pgd);
-	} else {
-		/*
-		 * For AP's, zap the low identity mappings by changing the cr3
-		 * to init_level4_pgt and doing local flush tlb all
-		 */
-		asm volatile("movq %0,%%cr3" :: "r" (__pa_symbol(&init_level4_pgt)));
-	}
-	__flush_tlb_all();
-}
-
 #ifndef CONFIG_NUMA
 void __init paging_init(void)
 {
@@ -569,15 +554,6 @@ void __init mem_init(void)
 		reservedpages << (PAGE_SHIFT-10),
 		datasize >> 10,
 		initsize >> 10);
-
-#ifdef CONFIG_SMP
-	/*
-	 * Sync boot_level4_pgt mappings with the init_level4_pgt
-	 * except for the low identity mappings which are already zapped
-	 * in init_level4_pgt. This sync-up is essential for AP's bringup
-	 */
-	memcpy(boot_level4_pgt+1, init_level4_pgt+1, (PTRS_PER_PGD-1)*sizeof(pgd_t));
-#endif
 }
 
 void free_init_pages(char *what, unsigned long begin, unsigned long end)
include/asm-x86_64/pgtable.h +0 -1
Index: linux/include/asm-x86_64/pgtable.h
===================================================================
@@ -17,7 +17,6 @@ extern pud_t level3_kernel_pgt[512];
 extern pud_t level3_ident_pgt[512];
 extern pmd_t level2_kernel_pgt[512];
 extern pgd_t init_level4_pgt[];
-extern pgd_t boot_level4_pgt[];
 extern unsigned long __supported_pte_mask;
 
 #define swapper_pg_dir init_level4_pgt
include/asm-x86_64/proto.h +0 -2
Index: linux/include/asm-x86_64/proto.h
===================================================================
@@ -11,8 +11,6 @@ struct pt_regs;
 extern void start_kernel(void);
 extern void pda_init(int); 
 
-extern void zap_low_mappings(int cpu);
-
 extern void early_idt_handler(void);
 
 extern void mcheck_init(struct cpuinfo_x86 *c);
author
#18 lore raw

PATCH 18/22 x86: __pa and __pa_symbol address space separation

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

Currently __pa_symbol is for use with symbols in the kernel address map and __pa is for use with pointers into the physical memory map. But the code is implemented so you can usually interchange the two.

__pa which is much more common can be implemented much more cheaply if it is it doesn't have to worry about any other kernel address spaces. This is especially true with a relocatable kernel as __pa_symbol needs to peform an extra variable read to resolve the address.

There is a third macro that is added for the vsyscall data __pa_vsymbol for finding the physical addesses of vsyscall pages.

Most of this patch is simply sorting through the references to __pa or __pa_symbol and using the proper one. A little of it is continuing to use a physical address when we have it instead of recalculating it several times.

swapper_pgd is now NULL. leave_mm now uses init_mm.pgd and init_mm.pgd is initialized at boot (instead of compile time) to the physmem virtual mapping of init_level4_pgd. The physical address changed.

Except for the for EMPTY_ZERO page all of the remaining references to __pa_symbol appear to be during kernel initialization. So this should reduce the cost of __pa in the common case, even on a relocated kernel.

As this is technically a semantic change we need to be on the lookout for anything I missed. But it works for me (tm).

---

 arch/i386/kernel/alternative.c     |    4 ++--
 arch/i386/mm/init.c                |   15 ++++++++-------
 arch/x86_64/kernel/machine_kexec.c |   14 +++++++-------
 arch/x86_64/kernel/setup.c         |    9 +++++----
 arch/x86_64/kernel/smp.c           |    2 +-
 arch/x86_64/kernel/vsyscall.c      |    9 +++++++--
 arch/x86_64/mm/init.c              |   21 +++++++++++----------
 arch/x86_64/mm/pageattr.c          |   16 ++++++++--------
 include/asm-x86_64/page.h          |    6 ++----
 include/asm-x86_64/pgtable.h       |    4 ++--
 10 files changed, 53 insertions(+), 47 deletions(-)
arch/i386/kernel/alternative.c +2 -2
Index: linux/arch/i386/kernel/alternative.c
===================================================================
@@ -402,8 +402,8 @@ void __init alternative_instructions(voi
 						_text, _etext);
 		}
 		free_init_pages("SMP alternatives",
-				(unsigned long)__smp_alt_begin,
-				(unsigned long)__smp_alt_end);
+				__pa_symbol(&__smp_alt_begin),
+				__pa_symbol(&__smp_alt_end));
 	} else {
 		alternatives_smp_save(__smp_alt_instructions,
 				      __smp_alt_instructions_end);
arch/i386/mm/init.c +8 -7
Index: linux/arch/i386/mm/init.c
===================================================================
@@ -774,10 +774,11 @@ void free_init_pages(char *what, unsigne
 	unsigned long addr;
 
 	for (addr = begin; addr < end; addr += PAGE_SIZE) {
-		ClearPageReserved(virt_to_page(addr));
-		init_page_count(virt_to_page(addr));
-		memset((void *)addr, POISON_FREE_INITMEM, PAGE_SIZE);
-		free_page(addr);
+		struct page *page = pfn_to_page(addr >> PAGE_SHIFT);
+		ClearPageReserved(page);
+		init_page_count(page);
+		memset(page_address(page), POISON_FREE_INITMEM, PAGE_SIZE);
+		__free_page(page);
 		totalram_pages++;
 	}
 	printk(KERN_INFO "Freeing %s: %ldk freed\n", what, (end - begin) >> 10);
@@ -786,14 +787,14 @@ void free_init_pages(char *what, unsigne
 void free_initmem(void)
 {
 	free_init_pages("unused kernel memory",
-			(unsigned long)(&__init_begin),
-			(unsigned long)(&__init_end));
+			__pa_symbol(&__init_begin),
+			__pa_symbol(&__init_end));
 }
 
 #ifdef CONFIG_BLK_DEV_INITRD
 void free_initrd_mem(unsigned long start, unsigned long end)
 {
-	free_init_pages("initrd memory", start, end);
+	free_init_pages("initrd memory", __pa(start), __pa(end));
 }
 #endif
 
arch/x86_64/kernel/machine_kexec.c +7 -7
Index: linux/arch/x86_64/kernel/machine_kexec.c
===================================================================
@@ -191,19 +191,19 @@ NORET_TYPE void machine_kexec(struct kim
 
 	page_list[PA_CONTROL_PAGE] = __pa(control_page);
 	page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
-	page_list[PA_PGD] = __pa(kexec_pgd);
+	page_list[PA_PGD] = __pa_symbol(&kexec_pgd);
 	page_list[VA_PGD] = (unsigned long)kexec_pgd;
-	page_list[PA_PUD_0] = __pa(kexec_pud0);
+	page_list[PA_PUD_0] = __pa_symbol(&kexec_pud0);
 	page_list[VA_PUD_0] = (unsigned long)kexec_pud0;
-	page_list[PA_PMD_0] = __pa(kexec_pmd0);
+	page_list[PA_PMD_0] = __pa_symbol(&kexec_pmd0);
 	page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;
-	page_list[PA_PTE_0] = __pa(kexec_pte0);
+	page_list[PA_PTE_0] = __pa_symbol(&kexec_pte0);
 	page_list[VA_PTE_0] = (unsigned long)kexec_pte0;
-	page_list[PA_PUD_1] = __pa(kexec_pud1);
+	page_list[PA_PUD_1] = __pa_symbol(&kexec_pud1);
 	page_list[VA_PUD_1] = (unsigned long)kexec_pud1;
-	page_list[PA_PMD_1] = __pa(kexec_pmd1);
+	page_list[PA_PMD_1] = __pa_symbol(&kexec_pmd1);
 	page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;
-	page_list[PA_PTE_1] = __pa(kexec_pte1);
+	page_list[PA_PTE_1] = __pa_symbol(&kexec_pte1);
 	page_list[VA_PTE_1] = (unsigned long)kexec_pte1;
 
 	page_list[PA_TABLE_PAGE] =
arch/x86_64/kernel/setup.c +5 -4
Index: linux/arch/x86_64/kernel/setup.c
===================================================================
@@ -243,11 +243,12 @@ void __init setup_arch(char **cmdline_p)
 	init_mm.end_code = (unsigned long) &_etext;
 	init_mm.end_data = (unsigned long) &_edata;
 	init_mm.brk = (unsigned long) &_end;
+	init_mm.pgd = __va(__pa_symbol(&init_level4_pgt));
 
-	code_resource.start = virt_to_phys(&_text);
-	code_resource.end = virt_to_phys(&_etext)-1;
-	data_resource.start = virt_to_phys(&_etext);
-	data_resource.end = virt_to_phys(&_edata)-1;
+	code_resource.start = __pa_symbol(&_text);
+	code_resource.end = __pa_symbol(&_etext)-1;
+	data_resource.start = __pa_symbol(&_etext);
+	data_resource.end = __pa_symbol(&_edata)-1;
 
 	early_identify_cpu(&boot_cpu_data);
 
arch/x86_64/kernel/smp.c +1 -1
Index: linux/arch/x86_64/kernel/smp.c
===================================================================
@@ -76,7 +76,7 @@ static inline void leave_mm(int cpu)
 	if (read_pda(mmu_state) == TLBSTATE_OK)
 		BUG();
 	cpu_clear(cpu, read_pda(active_mm)->cpu_vm_mask);
-	load_cr3(swapper_pg_dir);
+	load_cr3(init_mm.pgd);
 }
 
 /*
arch/x86_64/kernel/vsyscall.c +7 -2
Index: linux/arch/x86_64/kernel/vsyscall.c
===================================================================
@@ -45,6 +45,11 @@
 
 #define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr)))
 #define __syscall_clobber "r11","rcx","memory"
+#define __pa_vsymbol(x)			\
+	({unsigned long v;  		\
+	extern char __vsyscall_0; 	\
+	  asm("" : "=r" (v) : "0" (x)); \
+	  ((v - VSYSCALL_FIRST_PAGE) + __pa_symbol(&__vsyscall_0)); })
 
 struct vsyscall_gtod_data_t {
 	seqlock_t lock;
@@ -224,10 +229,10 @@ static int vsyscall_sysctl_change(ctl_ta
 		return ret;
 	/* gcc has some trouble with __va(__pa()), so just do it this
 	   way. */
-	map1 = ioremap(__pa_symbol(&vsysc1), 2);
+	map1 = ioremap(__pa_vsymbol(&vsysc1), 2);
 	if (!map1)
 		return -ENOMEM;
-	map2 = ioremap(__pa_symbol(&vsysc2), 2);
+	map2 = ioremap(__pa_vsymbol(&vsysc2), 2);
 	if (!map2) {
 		ret = -ENOMEM;
 		goto out;
arch/x86_64/mm/init.c +11 -10
Index: linux/arch/x86_64/mm/init.c
===================================================================
@@ -565,11 +565,11 @@ void free_init_pages(char *what, unsigne
 
 	printk(KERN_INFO "Freeing %s: %ldk freed\n", what, (end - begin) >> 10);
 	for (addr = begin; addr < end; addr += PAGE_SIZE) {
-		ClearPageReserved(virt_to_page(addr));
-		init_page_count(virt_to_page(addr));
-		memset((void *)(addr & ~(PAGE_SIZE-1)),
-			POISON_FREE_INITMEM, PAGE_SIZE);
-		free_page(addr);
+		struct page *page = pfn_to_page(addr >> PAGE_SHIFT);
+		ClearPageReserved(page);
+		init_page_count(page);
+		memset(page_address(page), POISON_FREE_INITMEM, PAGE_SIZE);
+		__free_page(page);
 		totalram_pages++;
 	}
 }
@@ -579,17 +579,18 @@ void free_initmem(void)
 	memset(__initdata_begin, POISON_FREE_INITDATA,
 		__initdata_end - __initdata_begin);
 	free_init_pages("unused kernel memory",
-			(unsigned long)(&__init_begin),
-			(unsigned long)(&__init_end));
+			__pa_symbol(&__init_begin),
+			__pa_symbol(&__init_end));
 }
 
 #ifdef CONFIG_DEBUG_RODATA
 
 void mark_rodata_ro(void)
 {
-	unsigned long addr = (unsigned long)__start_rodata;
+	unsigned long addr = (unsigned long)__va(__pa_symbol(&__start_rodata));
+	unsigned long end  = (unsigned long)__va(__pa_symbol(&__end_rodata));
 
-	for (; addr < (unsigned long)__end_rodata; addr += PAGE_SIZE)
+	for (; addr < end; addr += PAGE_SIZE)
 		change_page_attr_addr(addr, 1, PAGE_KERNEL_RO);
 
 	printk ("Write protecting the kernel read-only data: %luk\n",
@@ -608,7 +609,7 @@ void mark_rodata_ro(void)
 #ifdef CONFIG_BLK_DEV_INITRD
 void free_initrd_mem(unsigned long start, unsigned long end)
 {
-	free_init_pages("initrd memory", start, end);
+	free_init_pages("initrd memory", __pa(start), __pa(end));
 }
 #endif
 
arch/x86_64/mm/pageattr.c +8 -8
Index: linux/arch/x86_64/mm/pageattr.c
===================================================================
@@ -51,7 +51,6 @@ static struct page *split_large_page(uns
 	SetPagePrivate(base);
 	page_private(base) = 0;
 
-	address = __pa(address);
 	addr = address & LARGE_PAGE_MASK; 
 	pbase = (pte_t *)page_address(base);
 	for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
@@ -101,13 +100,12 @@ static inline void save_page(struct page
  * No more special protections in this 2/4MB area - revert to a
  * large page again. 
  */
-static void revert_page(unsigned long address, pgprot_t ref_prot)
+static void revert_page(unsigned long address, unsigned long pfn, pgprot_t ref_prot)
 {
 	pgd_t *pgd;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t large_pte;
-	unsigned long pfn;
 
 	pgd = pgd_offset_k(address);
 	BUG_ON(pgd_none(*pgd));
@@ -115,7 +113,6 @@ static void revert_page(unsigned long ad
 	BUG_ON(pud_none(*pud));
 	pmd = pmd_offset(pud, address);
 	BUG_ON(pmd_val(*pmd) & _PAGE_PSE);
-	pfn = (__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT;
 	large_pte = pfn_pte(pfn, ref_prot);
 	large_pte = pte_mkhuge(large_pte);
 	set_pte((pte_t *)pmd, large_pte);
@@ -141,7 +138,8 @@ __change_page_attr(unsigned long address
  			 */
 			struct page *split;
 			ref_prot2 = pte_pgprot(pte_clrhuge(*kpte));
-			split = split_large_page(address, prot, ref_prot2);
+			split = split_large_page(pfn << PAGE_SHIFT, prot,
+							ref_prot2);
 			if (!split)
 				return -ENOMEM;
 			set_pte(kpte, mk_pte(split, ref_prot2));
@@ -160,7 +158,7 @@ __change_page_attr(unsigned long address
 
 	if (page_private(kpte_page) == 0) {
 		save_page(kpte_page);
-		revert_page(address, ref_prot);
+		revert_page(address, pfn, ref_prot);
  	}
 	return 0;
 } 
@@ -180,6 +178,7 @@ __change_page_attr(unsigned long address
  */
 int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
 {
+	unsigned long phys_base_pfn = __pa_symbol(__START_KERNEL_map) >> PAGE_SHIFT;
 	int err = 0; 
 	int i; 
 
@@ -192,10 +191,11 @@ int change_page_attr_addr(unsigned long 
 			break; 
 		/* Handle kernel mapping too which aliases part of the
 		 * lowmem */
-		if (__pa(address) < KERNEL_TEXT_SIZE) {
+		if ((pfn >= phys_base_pfn) &&
+			((pfn - phys_base_pfn) < (KERNEL_TEXT_SIZE >> PAGE_SHIFT))) {
 			unsigned long addr2;
 			pgprot_t prot2;
-			addr2 = __START_KERNEL_map + __pa(address);
+			addr2 = __START_KERNEL_map + ((pfn - phys_base_pfn) << PAGE_SHIFT);
 			/* Make sure the kernel mappings stay executable */
 			prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
 			err = __change_page_attr(addr2, pfn, prot2,
include/asm-x86_64/page.h +2 -4
Index: linux/include/asm-x86_64/page.h
===================================================================
@@ -102,17 +102,15 @@ typedef struct { unsigned long pgprot; }
 
 /* Note: __pa(&symbol_visible_to_c) should be always replaced with __pa_symbol.
    Otherwise you risk miscompilation. */ 
-#define __pa(x)			(((unsigned long)(x)>=__START_KERNEL_map)?(unsigned long)(x) - (unsigned long)__START_KERNEL_map:(unsigned long)(x) - PAGE_OFFSET)
+#define __pa(x)			((unsigned long)(x) - PAGE_OFFSET)
 /* __pa_symbol should be used for C visible symbols.
    This seems to be the official gcc blessed way to do such arithmetic. */ 
 #define __pa_symbol(x)		\
 	({unsigned long v;  \
 	  asm("" : "=r" (v) : "0" (x)); \
-	  __pa(v); })
+	  (v - __START_KERNEL_map); })
 
 #define __va(x)			((void *)((unsigned long)(x)+PAGE_OFFSET))
-#define __boot_va(x)		__va(x)
-#define __boot_pa(x)		__pa(x)
 #ifdef CONFIG_FLATMEM
 #define pfn_valid(pfn)		((pfn) < end_pfn)
 #endif
include/asm-x86_64/pgtable.h +2 -2
Index: linux/include/asm-x86_64/pgtable.h
===================================================================
@@ -19,7 +19,7 @@ extern pmd_t level2_kernel_pgt[512];
 extern pgd_t init_level4_pgt[];
 extern unsigned long __supported_pte_mask;
 
-#define swapper_pg_dir init_level4_pgt
+#define swapper_pg_dir ((pgd_t *)NULL)
 
 extern void paging_init(void);
 extern void clear_kernel_mapping(unsigned long addr, unsigned long size);
@@ -29,7 +29,7 @@ extern void clear_kernel_mapping(unsigne
  * for zero-mapped memory areas etc..
  */
 extern unsigned long empty_zero_page[PAGE_SIZE/sizeof(unsigned long)];
-#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
+#define ZERO_PAGE(vaddr) (pfn_to_page(__pa_symbol(&empty_zero_page) >> PAGE_SHIFT))
 
 #endif /* !__ASSEMBLY__ */
 
author
#17 lore raw

PATCH 17/22 x86_64: do not use virt_to_page on kernel data address

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

o virt_to_page() call should be used on kernel linear addresses and not on kernel text and data addresses. Swsusp code uses it on kernel data (statically allocated swsusp_header).

o Allocate swsusp_header dynamically so that virt_to_page() can be used safely.

o I am changing this because in next few patches, __pa() on x86_64 will no longer support kernel text and data addresses and hibernation breaks.

---

 kernel/power/swap.c |   42 +++++++++++++++++++++++++++---------------
 1 file changed, 27 insertions(+), 15 deletions(-)
kernel/power/swap.c +27 -15
Index: linux/kernel/power/swap.c
===================================================================
@@ -33,12 +33,14 @@ extern char resume_file[];
 
 #define SWSUSP_SIG	"S1SUSPEND"
 
-static struct swsusp_header {
+struct swsusp_header {
 	char reserved[PAGE_SIZE - 20 - sizeof(sector_t)];
 	sector_t image;
 	char	orig_sig[10];
 	char	sig[10];
-} __attribute__((packed, aligned(PAGE_SIZE))) swsusp_header;
+} __attribute__((packed));
+
+static struct swsusp_header *swsusp_header;
 
 /*
  * General things
@@ -141,14 +143,14 @@ static int mark_swapfiles(sector_t start
 {
 	int error;
 
-	bio_read_page(swsusp_resume_block, &swsusp_header, NULL);
-	if (!memcmp("SWAP-SPACE",swsusp_header.sig, 10) ||
-	    !memcmp("SWAPSPACE2",swsusp_header.sig, 10)) {
-		memcpy(swsusp_header.orig_sig,swsusp_header.sig, 10);
-		memcpy(swsusp_header.sig,SWSUSP_SIG, 10);
-		swsusp_header.image = start;
+	bio_read_page(swsusp_resume_block, swsusp_header, NULL);
+	if (!memcmp("SWAP-SPACE",swsusp_header->sig, 10) ||
+	    !memcmp("SWAPSPACE2",swsusp_header->sig, 10)) {
+		memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10);
+		memcpy(swsusp_header->sig,SWSUSP_SIG, 10);
+		swsusp_header->image = start;
 		error = bio_write_page(swsusp_resume_block,
-					&swsusp_header, NULL);
+					swsusp_header, NULL);
 	} else {
 		printk(KERN_ERR "swsusp: Swap header not found!\n");
 		error = -ENODEV;
@@ -564,7 +566,7 @@ int swsusp_read(void)
 	if (error < PAGE_SIZE)
 		return error < 0 ? error : -EFAULT;
 	header = (struct swsusp_info *)data_of(snapshot);
-	error = get_swap_reader(&handle, swsusp_header.image);
+	error = get_swap_reader(&handle, swsusp_header->image);
 	if (!error)
 		error = swap_read_page(&handle, header, NULL);
 	if (!error)
@@ -591,17 +593,17 @@ int swsusp_check(void)
 	resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
 	if (!IS_ERR(resume_bdev)) {
 		set_blocksize(resume_bdev, PAGE_SIZE);
-		memset(&swsusp_header, 0, sizeof(swsusp_header));
+		memset(swsusp_header, 0, sizeof(PAGE_SIZE));
 		error = bio_read_page(swsusp_resume_block,
-					&swsusp_header, NULL);
+					swsusp_header, NULL);
 		if (error)
 			return error;
 
-		if (!memcmp(SWSUSP_SIG, swsusp_header.sig, 10)) {
-			memcpy(swsusp_header.sig, swsusp_header.orig_sig, 10);
+		if (!memcmp(SWSUSP_SIG, swsusp_header->sig, 10)) {
+			memcpy(swsusp_header->sig, swsusp_header->orig_sig, 10);
 			/* Reset swap signature now */
 			error = bio_write_page(swsusp_resume_block,
-						&swsusp_header, NULL);
+						swsusp_header, NULL);
 		} else {
 			return -EINVAL;
 		}
@@ -632,3 +634,13 @@ void swsusp_close(void)
 
 	blkdev_put(resume_bdev);
 }
+
+static int swsusp_header_init(void)
+{
+	swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
+	if (!swsusp_header)
+		panic("Could not allocate memory for swsusp_header\n");
+	return 0;
+}
+
+core_initcall(swsusp_header_init);
author
#21 lore raw

PATCH 21/22 x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

o Extend the bzImage protocol (same as i386) to allow bzImage loaders to load the protected mode kernel at non-1MB address. Now protected mode component is relocatable and can be loaded at non-1MB addresses.

o As of today kdump uses it to run a second kernel from a reserved memory area.

---

 arch/x86_64/boot/setup.S |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)
arch/x86_64/boot/setup.S +11 -2
Index: linux/arch/x86_64/boot/setup.S
===================================================================
@@ -80,7 +80,7 @@ start:
 # This is the setup header, and it must start at %cs:2 (old 0x9020:2)
 
 		.ascii	"HdrS"		# header signature
-		.word	0x0204		# header version number (>= 0x0105)
+		.word	0x0205		# header version number (>= 0x0105)
 					# or else old loadlin-1.5 will fail)
 realmode_swtch:	.word	0, 0		# default_switch, SETUPSEG
 start_sys_seg:	.word	SYSSEG
@@ -155,7 +155,16 @@ cmd_line_ptr:	.long 0			# (Header versio
 					# low memory 0x10000 or higher.
 
 ramdisk_max:	.long 0xffffffff
-	
+kernel_alignment:  .long 0x200000       # physical addr alignment required for
+					# protected mode relocatable kernel
+#ifdef CONFIG_RELOCATABLE
+relocatable_kernel:    .byte 1
+#else
+relocatable_kernel:    .byte 0
+#endif
+pad2:                  .byte 0
+pad3:                  .word 0
+
 trampoline:	call	start_of_setup
 		.align 16
 					# The offset at this point is 0x240
author
#201 lore raw

PATCH 22/22 x86_64: Move cpu verification code to common file

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

o This patch moves the code to verify long mode and SSE to a common file. This code is now shared by trampoline.S, wakeup.S, boot/setup.S and boot/compressed/head.S

o So far we used to do very limited check in trampoline.S, wakeup.S and in 32bit entry point. Now all the entry paths are forced to do the exhaustive check, including SSE because verify_cpu is shared.

o I am keeping this patch as last in the x86 relocatable series because previous patches have got quite some amount of testing done and don't want to distrub that. So that if there is problem introduced by this patch, at least it can be easily isolated.

---

 arch/x86_64/boot/compressed/head.S |   19 ++++++
 arch/x86_64/boot/setup.S           |   65 ++-------------------
 arch/x86_64/kernel/acpi/wakeup.S   |   30 +++++-----
 arch/x86_64/kernel/trampoline.S    |   51 +----------------
 arch/x86_64/kernel/verify_cpu.S    |  110 +++++++++++++++++++++++++++++++++++++
 5 files changed, 152 insertions(+), 123 deletions(-)
arch/x86_64/boot/compressed/head.S +18 -1
Index: linux/arch/x86_64/boot/compressed/head.S
===================================================================
@@ -54,6 +54,15 @@ startup_32:
 1:	popl	%ebp
 	subl	$1b, %ebp
 
+/* setup a stack and make sure cpu supports long mode. */
+	movl	$user_stack_end, %eax
+	addl	%ebp, %eax
+	movl	%eax, %esp
+
+	call	verify_cpu
+	testl	%eax, %eax
+	jnz	no_longmode
+
 /* Compute the delta between where we were compiled to run at
  * and where the code will actually run at.
  */
@@ -159,13 +168,21 @@ startup_32:
 	/* Jump from 32bit compatibility mode into 64bit mode. */
 	lret
 
+no_longmode:
+	/* This isn't an x86-64 CPU so hang */
+1:
+	hlt
+	jmp     1b
+
+#include "../../kernel/verify_cpu.S"
+
 	/* Be careful here startup_64 needs to be at a predictable
 	 * address so I can export it in an ELF header.  Bootloaders
 	 * should look at the ELF header to find this address, as
 	 * it may change in the future.
 	 */
 	.code64
-	.org 0x100
+	.org 0x200
 ENTRY(startup_64)
 	/* We come here either from startup_32 or directly from a
 	 * 64bit bootloader.  If we come here from a bootloader we depend on
arch/x86_64/boot/setup.S +6 -59

77 lines not on this page · raw message

arch/x86_64/kernel/acpi/wakeup.S +15 -15
Index: linux/arch/x86_64/kernel/acpi/wakeup.S
===================================================================
@@ -43,6 +43,11 @@ wakeup_code:
 	cmpl	$0x12345678, %eax
 	jne	bogus_real_magic
 
+  	call	verify_cpu			# Verify the cpu supports long
+						# mode
+	testl	%eax, %eax
+	jnz	no_longmode
+
 	testl	$1, video_flags - wakeup_code
 	jz	1f
 	lcall   $0xc000,$3
@@ -92,18 +97,6 @@ wakeup_32:
 # Running in this code, but at low address; paging is not yet turned on.
 	movb	$0xa5, %al	;  outb %al, $0x80
 
-	/* Check if extended functions are implemented */		
-	movl	$0x80000000, %eax
-	cpuid
-	cmpl	$0x80000000, %eax
-	jbe	bogus_cpu
-	wbinvd
-	mov	$0x80000001, %eax
-	cpuid
-	btl	$29, %edx
-	jnc	bogus_cpu
-	movl	%edx,%edi
-	
 	movl	$__KERNEL_DS, %eax
 	movl	%eax, %ds
 
@@ -123,6 +116,11 @@ wakeup_32:
 	leal    (wakeup_level4_pgt - wakeup_code)(%esi), %eax
 	movl	%eax, %cr3
 
+        /* Check if nx is implemented */
+        movl    $0x80000001, %eax
+        cpuid
+        movl    %edx,%edi
+
 	/* Enable Long Mode */
 	xorl    %eax, %eax
 	btsl	$_EFER_LME, %eax
@@ -244,10 +242,12 @@ bogus_64_magic:
 	movb	$0xb3,%al	;  outb %al,$0x80
 	jmp bogus_64_magic
 
-bogus_cpu:
-	movb	$0xbc,%al	;  outb %al,$0x80
-	jmp bogus_cpu
+.code16
+no_longmode:
+	movb    $0xbc,%al       ;  outb %al,$0x80
+	jmp no_longmode
 
+#include "../verify_cpu.S"
 	
 /* This code uses an extended set of video mode numbers. These include:
  * Aliases for standard modes
arch/x86_64/kernel/trampoline.S +3 -48

66 lines not on this page · raw message

arch/x86_64/kernel/verify_cpu.S new file +110 -0

110 lines not on this page · raw message

author
#20 lore raw

PATCH 20/22 x86_64: build-time checking

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

o X86_64 kernel should run from 2MB aligned address for two reasons.
- Performance.
- For relocatable kernels, page tables are updated based on difference between compile time address and load time physical address. This difference should be multiple of 2MB as kernel text and data is mapped using 2MB pages and PMD should be pointing to a 2MB aligned address. Life is simpler if both compile time and load time kernel addresses are 2MB aligned.

o Flag the error at compile time if one is trying to build a kernel which does not meet alignment restrictions.

---

 arch/x86_64/boot/compressed/misc.c |    2 +-
 arch/x86_64/kernel/head64.c        |    7 +++++++
 include/asm-x86_64/page.h          |    1 +
 3 files changed, 9 insertions(+), 1 deletion(-)
arch/x86_64/boot/compressed/misc.c +1 -1
Index: linux/arch/x86_64/boot/compressed/misc.c
===================================================================
@@ -358,7 +358,7 @@ asmlinkage void decompress_kernel(void *
 	insize = input_len;
 	inptr  = 0;
 
-	if ((ulg)output & 0x1fffffUL)
+	if ((ulg)output & (__KERNEL_ALIGN - 1))
 		error("Destination address not 2M aligned");
 	if ((ulg)output >= 0xffffffffffUL)
 		error("Destination address too large");
arch/x86_64/kernel/head64.c +7 -0
Index: linux/arch/x86_64/kernel/head64.c
===================================================================
@@ -62,6 +62,13 @@ void __init x86_64_start_kernel(char * r
 {
 	int i;
 
+	/*
+	 * Make sure kernel is aligned to 2MB address. Catching it at compile
+	 * time is better. Change your config file and compile the kernel
+	 * for a 2MB aligned address (CONFIG_PHYSICAL_START)
+	 */
+	BUILD_BUG_ON(CONFIG_PHYSICAL_START & (__KERNEL_ALIGN - 1));
+
 	/* clear bss before set_intr_gate with early_idt_handler */
 	clear_bss();
 
include/asm-x86_64/page.h +1 -0
Index: linux/include/asm-x86_64/page.h
===================================================================
@@ -78,6 +78,7 @@ extern unsigned long phys_base;
 #endif /* !__ASSEMBLY__ */
 
 #define __PHYSICAL_START	CONFIG_PHYSICAL_START
+#define __KERNEL_ALIGN		0x200000
 #define __START_KERNEL		(__START_KERNEL_map + __PHYSICAL_START)
 #define __START_KERNEL_map	0xffffffff80000000
 #define __PAGE_OFFSET           0xffff810000000000
author
#19 lore raw

PATCH 19/22 x86_64: Relocatable Kernel Support

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

This patch modifies the x86_64 kernel so that it can be loaded and run at any 2M aligned address, below 512G. The technique used is to compile the decompressor with -fPIC and modify it so the decompressor is fully relocatable. For the main kernel the page tables are modified so the kernel remains at the same virtual address. In addition a variable phys_base is kept that holds the physical address the kernel is loaded at. __pa_symbol is modified to add that when we take the address of a kernel symbol.

When loaded with a normal bootloader the decompressor will decompress the kernel to 2M and it will run there. This both ensures the relocation code is always working, and makes it easier to use 2M pages for the kernel and the cpu.

AK: changed to not make RELOCATABLE default in Kconfig

---

 arch/x86_64/Kconfig                     |   49 ++++
 arch/x86_64/boot/compressed/Makefile    |   12 -
 arch/x86_64/boot/compressed/head.S      |  322 +++++++++++++++++++++++---------
 arch/x86_64/boot/compressed/misc.c      |  251 +++++++++++++-----------
 arch/x86_64/boot/compressed/vmlinux.lds |   44 ++++
 arch/x86_64/boot/compressed/vmlinux.scr |    9 
 arch/x86_64/kernel/head.S               |  225 ++++++++++++----------
 arch/x86_64/kernel/suspend_asm.S        |    7 
 include/asm-x86_64/page.h               |    6 
 9 files changed, 595 insertions(+), 330 deletions(-)
arch/x86_64/boot/compressed/head.S +234 -88
Index: linux/arch/x86_64/boot/compressed/head.S
===================================================================
@@ -26,116 +26,262 @@
 
 #include <linux/linkage.h>
 #include <asm/segment.h>
+#include <asm/pgtable.h>
 #include <asm/page.h>
+#include <asm/msr.h>
 
+.section ".text.head"
 	.code32
 	.globl startup_32
-	
+
 startup_32:
 	cld
 	cli
-	movl $(__KERNEL_DS),%eax
-	movl %eax,%ds
-	movl %eax,%es
-	movl %eax,%fs
-	movl %eax,%gs
-
-	lss stack_start,%esp
-	xorl %eax,%eax
-1:	incl %eax		# check that A20 really IS enabled
-	movl %eax,0x000000	# loop forever if it isn't
-	cmpl %eax,0x100000
-	je 1b
+	movl	$(__KERNEL_DS), %eax
+	movl	%eax, %ds
+	movl	%eax, %es
+	movl	%eax, %ss
+
+/* Calculate the delta between where we were compiled to run
+ * at and where we were actually loaded at.  This can only be done
+ * with a short local call on x86.  Nothing  else will tell us what
+ * address we are running at.  The reserved chunk of the real-mode
+ * data at 0x34-0x3f are used as the stack for this calculation.
+ * Only 4 bytes are needed.
+ */
+	leal	0x40(%esi), %esp
+	call	1f
+1:	popl	%ebp
+	subl	$1b, %ebp
+
+/* Compute the delta between where we were compiled to run at
+ * and where the code will actually run at.
+ */
+/* %ebp contains the address we are loaded at by the boot loader and %ebx
+ * contains the address where we should move the kernel image temporarily
+ * for safe in-place decompression.
+ */
+
+#ifdef CONFIG_RELOCATABLE
+	movl	%ebp, %ebx
+	addl	$(LARGE_PAGE_SIZE -1), %ebx
+	andl	$LARGE_PAGE_MASK, %ebx
+#else
+	movl	$CONFIG_PHYSICAL_START, %ebx
+#endif
+
+	/* Replace the compressed data size with the uncompressed size */
+	subl	input_len(%ebp), %ebx
+	movl	output_len(%ebp), %eax
+	addl	%eax, %ebx
+	/* Add 8 bytes for every 32K input block */
+	shrl	$12, %eax
+	addl	%eax, %ebx
+	/* Add 32K + 18 bytes of extra slack and align on a 4K boundary */
+	addl	$(32768 + 18 + 4095), %ebx
+	andl	$~4095, %ebx
 
 /*
- * Initialize eflags.  Some BIOS's leave bits like NT set.  This would
- * confuse the debugger if this code is traced.
- * XXX - best to initialize before switching to protected mode.
+ * Prepare for entering 64 bit mode
  */
-	pushl $0
-	popfl
+
+	/* Load new GDT with the 64bit segments using 32bit descriptor */
+	leal	gdt(%ebp), %eax
+	movl	%eax, gdt+2(%ebp)
+	lgdt	gdt(%ebp)
+
+	/* Enable PAE mode */
+	xorl	%eax, %eax
+	orl	$(1 << 5), %eax
+	movl	%eax, %cr4
+
+ /*
+  * Build early 4G boot pagetable
+  */
+	/* Initialize Page tables to 0*/
+	leal	pgtable(%ebx), %edi
+	xorl	%eax, %eax
+	movl	$((4096*6)/4), %ecx
+	rep	stosl
+
+	/* Build Level 4 */
+	leal	pgtable + 0(%ebx), %edi
+	leal	0x1007 (%edi), %eax
+	movl	%eax, 0(%edi)
+
+	/* Build Level 3 */
+	leal	pgtable + 0x1000(%ebx), %edi
+	leal	0x1007(%edi), %eax
+	movl	$4, %ecx
+1:	movl	%eax, 0x00(%edi)
+	addl	$0x00001000, %eax
+	addl	$8, %edi
+	decl	%ecx
+	jnz	1b
+
+	/* Build Level 2 */
+	leal	pgtable + 0x2000(%ebx), %edi
+	movl	$0x00000183, %eax
+	movl	$2048, %ecx
+1:	movl	%eax, 0(%edi)
+	addl	$0x00200000, %eax
+	addl	$8, %edi
+	decl	%ecx
+	jnz	1b
+
+	/* Enable the boot page tables */
+	leal	pgtable(%ebx), %eax
+	movl	%eax, %cr3
+
+	/* Enable Long mode in EFER (Extended Feature Enable Register) */
+	movl	$MSR_EFER, %ecx
+	rdmsr
+	btsl	$_EFER_LME, %eax
+	wrmsr
+
+	/* Setup for the jump to 64bit mode
+	 *
+	 * When the jump is performend we will be in long mode but
+	 * in 32bit compatibility mode with EFER.LME = 1, CS.L = 0, CS.D = 1
+	 * (and in turn EFER.LMA = 1).	To jump into 64bit mode we use
+	 * the new gdt/idt that has __KERNEL_CS with CS.L = 1.
+	 * We place all of the values on our mini stack so lret can
+	 * used to perform that far jump.
+	 */
+	pushl	$__KERNEL_CS
+	leal	startup_64(%ebp), %eax
+	pushl	%eax
+
+	/* Enter paged protected Mode, activating Long Mode */
+	movl	$0x80000001, %eax /* Enable Paging and Protected mode */
+	movl	%eax, %cr0
+
+	/* Jump from 32bit compatibility mode into 64bit mode. */
+	lret
+
+	/* Be careful here startup_64 needs to be at a predictable
+	 * address so I can export it in an ELF header.  Bootloaders
+	 * should look at the ELF header to find this address, as
+	 * it may change in the future.
+	 */
+	.code64
+	.org 0x100
+ENTRY(startup_64)
+	/* We come here either from startup_32 or directly from a
+	 * 64bit bootloader.  If we come here from a bootloader we depend on
+	 * an identity mapped page table being provied that maps our
+	 * entire text+data+bss and hopefully all of memory.
+	 */
+
+	/* Setup data segments. */
+	xorl	%eax, %eax
+	movl	%eax, %ds
+	movl	%eax, %es
+	movl	%eax, %ss
+
+	/* Compute the decompressed kernel start address.  It is where
+	 * we were loaded at aligned to a 2M boundary. %rbp contains the
+	 * decompressed kernel start address.
+	 *
+	 * If it is a relocatable kernel then decompress and run the kernel
+	 * from load address aligned to 2MB addr, otherwise decompress and
+	 * run the kernel from CONFIG_PHYSICAL_START
+	 */
+
+	/* Start with the delta to where the kernel will run at. */
+#ifdef CONFIG_RELOCATABLE
+	leaq	startup_32(%rip) /* - $startup_32 */, %rbp
+	addq	$(LARGE_PAGE_SIZE - 1), %rbp
+	andq	$LARGE_PAGE_MASK, %rbp
+	movq	%rbp, %rbx
+#else
+	movq	$CONFIG_PHYSICAL_START, %rbp
+	movq	%rbp, %rbx
+#endif
+
+	/* Replace the compressed data size with the uncompressed size */
+	movl	input_len(%rip), %eax
+	subq	%rax, %rbx
+	movl	output_len(%rip), %eax
+	addq	%rax, %rbx
+	/* Add 8 bytes for every 32K input block */
+	shrq	$12, %rax
+	addq	%rax, %rbx
+	/* Add 32K + 18 bytes of extra slack and align on a 4K boundary */
+	addq	$(32768 + 18 + 4095), %rbx
+	andq	$~4095, %rbx
+
+/* Copy the compressed kernel to the end of our buffer
+ * where decompression in place becomes safe.
+ */
+	leaq	_end(%rip), %r8
+	leaq	_end(%rbx), %r9
+	movq	$_end /* - $startup_32 */, %rcx
+1:	subq	$8, %r8
+	subq	$8, %r9
+	movq	0(%r8), %rax
+	movq	%rax, 0(%r9)
+	subq	$8, %rcx
+	jnz	1b
+
+/*
+ * Jump to the relocated address.
+ */
+	leaq	relocated(%rbx), %rax
+	jmp	*%rax
+
+.section ".text"
+relocated:
+
 /*
  * Clear BSS
  */
-	xorl %eax,%eax
-	movl $_edata,%edi
-	movl $_end,%ecx
-	subl %edi,%ecx
+	xorq	%rax, %rax
+	leaq    _edata(%rbx), %rdi
+	leaq    _end(%rbx), %rcx
+	subq	%rdi, %rcx
 	cld
 	rep
 	stosb
+
+	/* Setup the stack */
+	leaq	user_stack_end(%rip), %rsp
+
+	/* zero EFLAGS after setting rsp */
+	pushq	$0
+	popfq
+
 /*
  * Do the decompression, and jump to the new kernel..
  */
-	subl $16,%esp	# place for structure on the stack
-	movl %esp,%eax
-	pushl %esi	# real mode pointer as second arg
-	pushl %eax	# address of structure as first arg
-	call decompress_kernel
-	orl  %eax,%eax 
-	jnz  3f
-	addl $8,%esp
-	xorl %ebx,%ebx
-	ljmp $(__KERNEL_CS), $__PHYSICAL_START
-
-/*
- * We come here, if we were loaded high.
- * We need to move the move-in-place routine down to 0x1000
- * and then start it with the buffer addresses in registers,
- * which we got from the stack.
- */
-3:
-	movl %esi,%ebx	
-	movl $move_routine_start,%esi
-	movl $0x1000,%edi
-	movl $move_routine_end,%ecx
-	subl %esi,%ecx
-	addl $3,%ecx
-	shrl $2,%ecx
-	cld
-	rep
-	movsl
+	pushq	%rsi			# Save the real mode argument
+	movq	%rsi, %rdi		# real mode address
+	leaq	_heap(%rip), %rsi	# _heap
+	leaq	input_data(%rip), %rdx  # input_data
+	movl	input_len(%rip), %eax
+	movq	%rax, %rcx		# input_len
+	movq	%rbp, %r8		# output
+	call	decompress_kernel
+	popq	%rsi
 
-	popl %esi	# discard the address
-	addl $4,%esp	# real mode pointer
-	popl %esi	# low_buffer_start
-	popl %ecx	# lcount
-	popl %edx	# high_buffer_start
-	popl %eax	# hcount
-	movl $__PHYSICAL_START,%edi
-	cli		# make sure we don't get interrupted
-	ljmp $(__KERNEL_CS), $0x1000 # and jump to the move routine
 
 /*
- * Routine (template) for moving the decompressed kernel in place,
- * if we were high loaded. This _must_ PIC-code !
+ * Jump to the decompressed kernel.
  */
-move_routine_start:
-	movl %ecx,%ebp
-	shrl $2,%ecx
-	rep
-	movsl
-	movl %ebp,%ecx
-	andl $3,%ecx
-	rep
-	movsb
-	movl %edx,%esi
-	movl %eax,%ecx	# NOTE: rep movsb won't move if %ecx == 0
-	addl $3,%ecx
-	shrl $2,%ecx
-	rep
-	movsl
-	movl %ebx,%esi	# Restore setup pointer
-	xorl %ebx,%ebx
-	ljmp $(__KERNEL_CS), $__PHYSICAL_START
-move_routine_end:
+	jmp	*%rbp
 
-
-/* Stack for uncompression */ 	
-	.align 32
-user_stack:	 	
+	.data
+gdt:
+	.word	gdt_end - gdt
+	.long	gdt
+	.word	0
+	.quad	0x0000000000000000	/* NULL descriptor */
+	.quad	0x00af9a000000ffff	/* __KERNEL_CS */
+	.quad	0x00cf92000000ffff	/* __KERNEL_DS */
+gdt_end:
+	.bss
+/* Stack for uncompression */
+	.balign 4
+user_stack:
 	.fill 4096,4,0
-stack_start:	
-	.long user_stack+4096
-	.word __KERNEL_DS
-
+user_stack_end:
arch/x86_64/boot/compressed/Makefile +5 -7
Index: linux/arch/x86_64/boot/compressed/Makefile
===================================================================
@@ -8,16 +8,14 @@
 
 targets		:= vmlinux vmlinux.bin vmlinux.bin.gz head.o misc.o piggy.o
 EXTRA_AFLAGS	:= -traditional
-AFLAGS		:= $(subst -m64,-m32,$(AFLAGS))
 
 # cannot use EXTRA_CFLAGS because base CFLAGS contains -mkernel which conflicts with
 # -m32
-CFLAGS := -m32 -D__KERNEL__ -Iinclude -O2  -fno-strict-aliasing
-LDFLAGS := -m elf_i386
+CFLAGS := -m64 -D__KERNEL__ -Iinclude -O2  -fno-strict-aliasing -fPIC -mcmodel=small -fno-builtin
+LDFLAGS := -m elf_x86_64
 
-LDFLAGS_vmlinux := -Ttext $(IMAGE_OFFSET) -e startup_32 -m elf_i386
-
-$(obj)/vmlinux: $(obj)/head.o $(obj)/misc.o $(obj)/piggy.o FORCE
+LDFLAGS_vmlinux := -T
+$(obj)/vmlinux: $(src)/vmlinux.lds $(obj)/head.o $(obj)/misc.o $(obj)/piggy.o FORCE
 	$(call if_changed,ld)
 	@:
 
@@ -27,7 +25,7 @@ $(obj)/vmlinux.bin: vmlinux FORCE
 $(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
 	$(call if_changed,gzip)
 
-LDFLAGS_piggy.o := -r --format binary --oformat elf32-i386 -T
+LDFLAGS_piggy.o := -r --format binary --oformat elf64-x86-64 -T
 
 $(obj)/piggy.o: $(obj)/vmlinux.scr $(obj)/vmlinux.bin.gz FORCE
 	$(call if_changed,ld)
arch/x86_64/boot/compressed/misc.c +132 -119

310 lines not on this page · raw message

arch/x86_64/boot/compressed/vmlinux.lds new file +44 -0

44 lines not on this page · raw message

arch/x86_64/boot/compressed/vmlinux.scr +5 -4
Index: linux/arch/x86_64/boot/compressed/vmlinux.scr
===================================================================
@@ -1,9 +1,10 @@
 SECTIONS
 {
-  .data : { 
+  .text.compressed : {
 	input_len = .;
-	LONG(input_data_end - input_data) input_data = .; 
-	*(.data) 
-	input_data_end = .; 
+	LONG(input_data_end - input_data) input_data = .;
+	*(.data)
+	output_len = . - 4;
+	input_data_end = .;
 	}
 }
arch/x86_64/Kconfig +41 -8

64 lines not on this page · raw message

arch/x86_64/kernel/head.S +126 -99

307 lines not on this page · raw message

arch/x86_64/kernel/suspend_asm.S +4 -3
Index: linux/arch/x86_64/kernel/suspend_asm.S
===================================================================
@@ -71,9 +71,10 @@ loop:
 	jmp	loop
 done:
 	/* go back to the original page tables */
-	leaq	init_level4_pgt(%rip), %rax
-	subq	$__START_KERNEL_map, %rax
-	movq	%rax, %cr3
+	movq    $(init_level4_pgt - __START_KERNEL_map), %rax
+	addq    phys_base(%rip), %rax
+	movq    %rax, %cr3
+
 	/* Flush TLB, including "global" things (vmalloc) */
 	movq	mmu_cr4_features(%rip), %rax
 	movq	%rax, %rdx
include/asm-x86_64/page.h +4 -2
Index: linux/include/asm-x86_64/page.h
===================================================================
@@ -61,6 +61,8 @@ typedef struct { unsigned long pgd; } pg
 
 typedef struct { unsigned long pgprot; } pgprot_t;
 
+extern unsigned long phys_base;
+
 #define pte_val(x)	((x).pte)
 #define pmd_val(x)	((x).pmd)
 #define pud_val(x)	((x).pud)
@@ -101,14 +103,14 @@ typedef struct { unsigned long pgprot; }
 #define PAGE_OFFSET		__PAGE_OFFSET
 
 /* Note: __pa(&symbol_visible_to_c) should be always replaced with __pa_symbol.
-   Otherwise you risk miscompilation. */ 
+   Otherwise you risk miscompilation. */
 #define __pa(x)			((unsigned long)(x) - PAGE_OFFSET)
 /* __pa_symbol should be used for C visible symbols.
    This seems to be the official gcc blessed way to do such arithmetic. */ 
 #define __pa_symbol(x)		\
 	({unsigned long v;  \
 	  asm("" : "=r" (v) : "0" (x)); \
-	  (v - __START_KERNEL_map); })
+	  ((v - __START_KERNEL_map) + phys_base); })
 
 #define __va(x)			((void *)((unsigned long)(x)+PAGE_OFFSET))
 #ifdef CONFIG_FLATMEM
author
#16 lore raw

PATCH 16/22 x86: Move swsusp __pa() dependent code to arch portion

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

o __pa() should be used only on kernel linearly mapped virtual addresses and not on kernel text and data addresses.

o Hibernation code needs to determine the physical address associated with kernel symbol to mark a section boundary which contains pages which don't have to be saved and restored during hibernate/resume operation.

o Move this piece of code in arch dependent section. So that architectures which don't have kernel text/data mapped into kernel linearly mapped region can come up with their own ways of determining physical addresses associated with a kernel text.

---

 arch/i386/power/suspend.c     |   14 ++++++++++++++
 arch/powerpc/kernel/Makefile  |    1 +
 arch/powerpc/kernel/suspend.c |   24 ++++++++++++++++++++++++
 arch/x86_64/kernel/suspend.c  |   14 ++++++++++++++
 kernel/power/power.h          |    5 ++---
 kernel/power/snapshot.c       |   11 -----------
 6 files changed, 55 insertions(+), 14 deletions(-)
arch/i386/power/suspend.c +14 -0
Index: linux/arch/i386/power/suspend.c
===================================================================
@@ -16,6 +16,9 @@
 /* Defined in arch/i386/power/swsusp.S */
 extern int restore_image(void);
 
+/* References to section boundaries */
+extern const void __nosave_begin, __nosave_end;
+
 /* Pointer to the temporary resume page tables */
 pgd_t *resume_pg_dir;
 
@@ -156,3 +159,14 @@ int swsusp_arch_resume(void)
 	restore_image();
 	return 0;
 }
+
+/*
+ *	pfn_is_nosave - check if given pfn is in the 'nosave' section
+ */
+
+int pfn_is_nosave(unsigned long pfn)
+{
+	unsigned long nosave_begin_pfn = __pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
+	unsigned long nosave_end_pfn = PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;
+	return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
+}
arch/powerpc/kernel/Makefile +1 -0
Index: linux/arch/powerpc/kernel/Makefile
===================================================================
@@ -37,6 +37,7 @@ obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
 obj-$(CONFIG_6xx)		+= idle_6xx.o l2cr_6xx.o cpu_setup_6xx.o
 obj-$(CONFIG_TAU)		+= tau_6xx.o
 obj32-$(CONFIG_SOFTWARE_SUSPEND) += swsusp_32.o
+obj-$(CONFIG_SOFTWARE_SUSPEND) += suspend.o
 obj32-$(CONFIG_MODULES)		+= module_32.o
 
 ifeq ($(CONFIG_PPC_MERGE),y)
arch/powerpc/kernel/suspend.c new file +24 -0
Index: linux/arch/powerpc/kernel/suspend.c
===================================================================
@@ -0,0 +1,24 @@
+/*
+ * Suspend support specific for power.
+ *
+ * Distribute under GPLv2
+ *
+ * Copyright (c) 2002 Pavel Machek <[email protected]>
+ * Copyright (c) 2001 Patrick Mochel <[email protected]>
+ */
+
+#include <asm/page.h>
+
+/* References to section boundaries */
+extern const void __nosave_begin, __nosave_end;
+
+/*
+ *	pfn_is_nosave - check if given pfn is in the 'nosave' section
+ */
+
+int pfn_is_nosave(unsigned long pfn)
+{
+	unsigned long nosave_begin_pfn = __pa(&__nosave_begin) >> PAGE_SHIFT;
+	unsigned long nosave_end_pfn = PAGE_ALIGN(__pa(&__nosave_end)) >> PAGE_SHIFT;
+	return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
+}
arch/x86_64/kernel/suspend.c +14 -0
Index: linux/arch/x86_64/kernel/suspend.c
===================================================================
@@ -13,6 +13,9 @@
 #include <asm/page.h>
 #include <asm/pgtable.h>
 
+/* References to section boundaries */
+extern const void __nosave_begin, __nosave_end;
+
 struct saved_context saved_context;
 
 unsigned long saved_context_eax, saved_context_ebx, saved_context_ecx, saved_context_edx;
@@ -220,4 +223,15 @@ int swsusp_arch_resume(void)
 	restore_image();
 	return 0;
 }
+
+/*
+ *	pfn_is_nosave - check if given pfn is in the 'nosave' section
+ */
+
+int pfn_is_nosave(unsigned long pfn)
+{
+	unsigned long nosave_begin_pfn = __pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
+	unsigned long nosave_end_pfn = PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;
+	return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
+}
 #endif /* CONFIG_SOFTWARE_SUSPEND */
kernel/power/power.h +2 -3
Index: linux/kernel/power/power.h
===================================================================
@@ -23,6 +23,8 @@ static inline int pm_suspend_disk(void)
 }
 #endif
 
+extern int pfn_is_nosave(unsigned long);
+
 extern struct mutex pm_mutex;
 
 #define power_attr(_name) \
@@ -37,9 +39,6 @@ static struct subsys_attribute _name##_a
 
 extern struct subsystem power_subsys;
 
-/* References to section boundaries */
-extern const void __nosave_begin, __nosave_end;
-
 /* Preferred image size in bytes (default 500 MB) */
 extern unsigned long image_size;
 extern int in_suspend;
kernel/power/snapshot.c +0 -11
Index: linux/kernel/power/snapshot.c
===================================================================
@@ -651,17 +651,6 @@ static inline unsigned int count_highmem
 #endif /* CONFIG_HIGHMEM */
 
 /**
- *	pfn_is_nosave - check if given pfn is in the 'nosave' section
- */
-
-static inline int pfn_is_nosave(unsigned long pfn)
-{
-	unsigned long nosave_begin_pfn = __pa(&__nosave_begin) >> PAGE_SHIFT;
-	unsigned long nosave_end_pfn = PAGE_ALIGN(__pa(&__nosave_end)) >> PAGE_SHIFT;
-	return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
-}
-
-/**
  *	saveable - Determine whether a non-highmem page should be included in
  *	the suspend image.
  *
author
#11 lore raw

PATCH 11/22 x86_64: wakeup.S rename registers to reflect right names

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

o Use appropriate names for 64bit regsiters.

---

 arch/x86_64/kernel/acpi/wakeup.S |   36 ++++++++++++++++++------------------
 include/asm-x86_64/suspend.h     |   12 ++++++------
 2 files changed, 24 insertions(+), 24 deletions(-)
arch/x86_64/kernel/acpi/wakeup.S +18 -18
Index: linux/arch/x86_64/kernel/acpi/wakeup.S
===================================================================
@@ -211,16 +211,16 @@ wakeup_long64:
 	movw	%ax, %es
 	movw	%ax, %fs
 	movw	%ax, %gs
-	movq	saved_esp, %rsp
+	movq	saved_rsp, %rsp
 
 	movw	$0x0e00 + 'x', %ds:(0xb8018)
-	movq	saved_ebx, %rbx
-	movq	saved_edi, %rdi
-	movq	saved_esi, %rsi
-	movq	saved_ebp, %rbp
+	movq	saved_rbx, %rbx
+	movq	saved_rdi, %rdi
+	movq	saved_rsi, %rsi
+	movq	saved_rbp, %rbp
 
 	movw	$0x0e00 + '!', %ds:(0xb801a)
-	movq	saved_eip, %rax
+	movq	saved_rip, %rax
 	jmp	*%rax
 
 .code32
@@ -408,13 +408,13 @@ do_suspend_lowlevel:
 	movq %r15, saved_context_r15(%rip)
 	pushfq ; popq saved_context_eflags(%rip)
 
-	movq	$.L97, saved_eip(%rip)
+	movq	$.L97, saved_rip(%rip)
 
-	movq %rsp,saved_esp
-	movq %rbp,saved_ebp
-	movq %rbx,saved_ebx
-	movq %rdi,saved_edi
-	movq %rsi,saved_esi
+	movq %rsp,saved_rsp
+	movq %rbp,saved_rbp
+	movq %rbx,saved_rbx
+	movq %rdi,saved_rdi
+	movq %rsi,saved_rsi
 
 	addq	$8, %rsp
 	movl	$3, %edi
@@ -461,12 +461,12 @@ do_suspend_lowlevel:
 	
 .data
 ALIGN
-ENTRY(saved_ebp)	.quad	0
-ENTRY(saved_esi)	.quad	0
-ENTRY(saved_edi)	.quad	0
-ENTRY(saved_ebx)	.quad	0
+ENTRY(saved_rbp)	.quad	0
+ENTRY(saved_rsi)	.quad	0
+ENTRY(saved_rdi)	.quad	0
+ENTRY(saved_rbx)	.quad	0
 
-ENTRY(saved_eip)	.quad	0
-ENTRY(saved_esp)	.quad	0
+ENTRY(saved_rip)	.quad	0
+ENTRY(saved_rsp)	.quad	0
 
 ENTRY(saved_magic)	.quad	0
include/asm-x86_64/suspend.h +6 -6
Index: linux/include/asm-x86_64/suspend.h
===================================================================
@@ -45,12 +45,12 @@ extern unsigned long saved_context_eflag
 extern void fix_processor_context(void);
 
 #ifdef CONFIG_ACPI_SLEEP
-extern unsigned long saved_eip;
-extern unsigned long saved_esp;
-extern unsigned long saved_ebp;
-extern unsigned long saved_ebx;
-extern unsigned long saved_esi;
-extern unsigned long saved_edi;
+extern unsigned long saved_rip;
+extern unsigned long saved_rsp;
+extern unsigned long saved_rbp;
+extern unsigned long saved_rbx;
+extern unsigned long saved_rsi;
+extern unsigned long saved_rdi;
 
 /* routines for saving/restoring kernel state */
 extern int acpi_save_state_mem(void);
author
#12 lore raw

PATCH 12/22 x86_64: wakeup.S misc cleanups

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

o Various cleanups. One of the main purpose of cleanups is that make wakeup.S as close as possible to trampoline.S.

o Following are the changes
- Indentations for comments.
- Changed the gdt table to compact form and to resemble the one in trampoline.S
- Take the jump to 32bit from real mode using ljmpl. Makes code more readable.
- After enabling long mode, directly take a long jump for 64bit mode. No need to take an extra jump to "reach_comaptibility_mode"
- Stack is not used after real mode. So don't load stack in 32 bit mode.
- No need to enable PGE here.
- No need to do extra EFER read, anyway we trash the read contents.
- No need to enable system call (EFER_SCE). Anyway it will be enabled when original EFER is restored.
- No need to set MP, ET, NE, WP, AM bits in cr0. Very soon we will reload the original cr0 while restroing the processor state.

---

 arch/x86_64/kernel/acpi/wakeup.S |  112 +++++++++++++--------------------------
 1 file changed, 40 insertions(+), 72 deletions(-)
arch/x86_64/kernel/acpi/wakeup.S +40 -72
Index: linux/arch/x86_64/kernel/acpi/wakeup.S
===================================================================
@@ -30,11 +30,12 @@ wakeup_code:
 	cld
 	# setup data segment
 	movw	%cs, %ax
-	movw	%ax, %ds					# Make ds:0 point to wakeup_start
+	movw	%ax, %ds		# Make ds:0 point to wakeup_start
 	movw	%ax, %ss
-	mov	$(wakeup_stack - wakeup_code), %sp		# Private stack is needed for ASUS board
+					# Private stack is needed for ASUS board
+	mov	$(wakeup_stack - wakeup_code), %sp
 
-	pushl	$0						# Kill any dangerous flags
+	pushl	$0			# Kill any dangerous flags
 	popfl
 
 	movl	real_magic - wakeup_code, %eax
@@ -45,7 +46,7 @@ wakeup_code:
 	jz	1f
 	lcall   $0xc000,$3
 	movw	%cs, %ax
-	movw	%ax, %ds					# Bios might have played with that
+	movw	%ax, %ds		# Bios might have played with that
 	movw	%ax, %ss
 1:
 
@@ -75,9 +76,12 @@ wakeup_code:
 	jmp	1f
 1:
 
-	.byte 0x66, 0xea			# prefix + jmpi-opcode
-	.long	wakeup_32 - __START_KERNEL_map
-	.word	__KERNEL_CS
+	ljmpl   *(wakeup_32_vector - wakeup_code)
+
+	.balign 4
+wakeup_32_vector:
+	.long   wakeup_32 - __START_KERNEL_map
+	.word   __KERNEL32_CS, 0
 
 	.code32
 wakeup_32:
@@ -96,65 +100,50 @@ wakeup_32:
 	jnc	bogus_cpu
 	movl	%edx,%edi
 	
-	movw	$__KERNEL_DS, %ax
-	movw	%ax, %ds
-	movw	%ax, %es
-	movw	%ax, %fs
-	movw	%ax, %gs
+	movl	$__KERNEL_DS, %eax
+	movl	%eax, %ds
 
-	movw	$__KERNEL_DS, %ax	
-	movw	%ax, %ss
-
-	mov	$(wakeup_stack - __START_KERNEL_map), %esp
 	movl	saved_magic - __START_KERNEL_map, %eax
 	cmpl	$0x9abcdef0, %eax
 	jne	bogus_32_magic
 
+	movw	$0x0e00 + 'i', %ds:(0xb8012)
+	movb	$0xa8, %al	;  outb %al, $0x80;
+
 	/*
 	 * Prepare for entering 64bits mode
 	 */
 
-	/* Enable PAE mode and PGE */
+	/* Enable PAE */
 	xorl	%eax, %eax
 	btsl	$5, %eax
-	btsl	$7, %eax
 	movl	%eax, %cr4
 
 	/* Setup early boot stage 4 level pagetables */
 	movl	$(wakeup_level4_pgt - __START_KERNEL_map), %eax
 	movl	%eax, %cr3
 
-	/* Setup EFER (Extended Feature Enable Register) */
-	movl	$MSR_EFER, %ecx
-	rdmsr
-	/* Fool rdmsr and reset %eax to avoid dependences */
-	xorl	%eax, %eax
 	/* Enable Long Mode */
+	xorl    %eax, %eax
 	btsl	$_EFER_LME, %eax
-	/* Enable System Call */
-	btsl	$_EFER_SCE, %eax
 
-	/* No Execute supported? */	
+	/* No Execute supported? */
 	btl	$20,%edi
 	jnc     1f
 	btsl	$_EFER_NX, %eax
-1:	
 				
 	/* Make changes effective */
+1:	movl    $MSR_EFER, %ecx
+	xorl    %edx, %edx
 	wrmsr
-	wbinvd
 
 	xorl	%eax, %eax
 	btsl	$31, %eax			/* Enable paging and in turn activate Long Mode */
 	btsl	$0, %eax			/* Enable protected mode */
-	btsl	$1, %eax			/* Enable MP */
-	btsl	$4, %eax			/* Enable ET */
-	btsl	$5, %eax			/* Enable NE */
-	btsl	$16, %eax			/* Enable WP */
-	btsl	$18, %eax			/* Enable AM */
 
 	/* Make changes effective */
 	movl	%eax, %cr0
+
 	/* At this point:
 		CR4.PAE must be 1
 		CS.L must be 0
@@ -162,11 +151,6 @@ wakeup_32:
 		Next instruction must be a branch
 		This must be on identity-mapped page
 	*/
-	jmp	reach_compatibility_mode
-reach_compatibility_mode:
-	movw	$0x0e00 + 'i', %ds:(0xb8012)
-	movb	$0xa8, %al	;  outb %al, $0x80; 	
-		
 	/*
 	 * At this point we're in long mode but in 32bit compatibility mode
 	 * with EFER.LME = 1, CS.L = 0, CS.D = 1 (and in turn
@@ -174,24 +158,19 @@ reach_compatibility_mode:
 	 * the new gdt/idt that has __KERNEL_CS with CS.L = 1.
 	 */
 
-	movw	$0x0e00 + 'n', %ds:(0xb8014)
-	movb	$0xa9, %al	;  outb %al, $0x80
-	
-	/* Load new GDT with the 64bit segment using 32bit descriptor */
-	movl	$(pGDT32 - __START_KERNEL_map), %eax
-	lgdt	(%eax)
-
-	movl    $(wakeup_jumpvector - __START_KERNEL_map), %eax
 	/* Finally jump in 64bit mode */
-	ljmp	*(%eax)
+	ljmp	*(wakeup_long64_vector - __START_KERNEL_map)
 
-wakeup_jumpvector:
-	.long	wakeup_long64 - __START_KERNEL_map
-	.word	__KERNEL_CS
+	.balign 4
+wakeup_long64_vector:
+	.long   wakeup_long64 - __START_KERNEL_map
+	.word   __KERNEL_CS, 0
 
 .code64
 
-	/*	Hooray, we are in Long 64-bit mode (but still running in low memory) */
+	/* Hooray, we are in Long 64-bit mode (but still running in
+	 * low memory)
+	 */
 wakeup_long64:
 	/*
 	 * We must switch to a new descriptor in kernel space for the GDT
@@ -201,6 +180,9 @@ wakeup_long64:
 	 */
 	lgdt	cpu_gdt_descr - __START_KERNEL_map
 
+	movw	$0x0e00 + 'n', %ds:(0xb8014)
+	movb	$0xa9, %al	;  outb %al, $0x80
+
 	movw	$0x0e00 + 'u', %ds:(0xb8016)
 	
 	nop
@@ -227,33 +209,19 @@ wakeup_long64:
 
 	.align	64	
 gdta:
+	/* Its good to keep gdt in sync with one in trampoline.S */
 	.word	0, 0, 0, 0			# dummy
-
-	.word	0, 0, 0, 0			# unused
-
-	.word	0xFFFF				# 4Gb - (0x100000*0x1000 = 4Gb)
-	.word	0				# base address = 0
-	.word	0x9B00				# code read/exec. ??? Why I need 0x9B00 (as opposed to 0x9A00 in order for this to work?)
-	.word	0x00CF				# granularity = 4096, 386
-						#  (+5th nibble of limit)
-
-	.word	0xFFFF				# 4Gb - (0x100000*0x1000 = 4Gb)
-	.word	0				# base address = 0
-	.word	0x9200				# data read/write
-	.word	0x00CF				# granularity = 4096, 386
-						#  (+5th nibble of limit)
-# this is 64bit descriptor for code
-	.word	0xFFFF
-	.word	0
-	.word	0x9A00				# code read/exec
-	.word	0x00AF				# as above, but it is long mode and with D=0
+	/* ??? Why I need the accessed bit set in order for this to work? */
+	.quad   0x00cf9b000000ffff              # __KERNEL32_CS
+	.quad   0x00af9b000000ffff              # __KERNEL_CS
+	.quad   0x00cf93000000ffff              # __KERNEL_DS
 
 idt_48a:
 	.word	0				# idt limit = 0
 	.word	0, 0				# idt base = 0L
 
 gdt_48a:
-	.word	0x8000				# gdt limit=2048,
+	.word	0x800				# gdt limit=2048,
 						#  256 GDT entries
 	.word	0, 0				# gdt base (filled in later)
 	
@@ -263,7 +231,7 @@ video_mode:	.quad 0
 video_flags:	.quad 0
 
 bogus_real_magic:
-	movb	$0xba,%al	;  outb %al,$0x80		
+	movb	$0xba,%al	;  outb %al,$0x80
 	jmp bogus_real_magic
 
 bogus_32_magic:
author
#9 lore raw

PATCH 9/22 x86_64: 64bit PIC SMP trampoline

In reply to Andi Kleen

From: Vivek Goyal <[email protected]>

This modifies the SMP trampoline and all of the associated code so it can jump to a 64bit kernel loaded at an arbitrary address.

The dependencies on having an idenetity mapped page in the kernel page tables for SMP bootup have all been removed.

In addition the trampoline has been modified to verify that long mode is supported. Asking if long mode is implemented is down right silly but we have traditionally had some of these checks, and they can't hurt anything. So when the totally ludicrous happens we just might handle it correctly.

---

 arch/x86_64/kernel/head.S       |    1 
 arch/x86_64/kernel/setup.c      |    9 --
 arch/x86_64/kernel/trampoline.S |  168 ++++++++++++++++++++++++++++++++++++----
 3 files changed, 156 insertions(+), 22 deletions(-)
arch/x86_64/kernel/head.S +1 -0
Index: linux/arch/x86_64/kernel/head.S
===================================================================
@@ -101,6 +101,7 @@ startup_32:
 	.org 0x100	
 	.globl startup_64
 startup_64:
+ENTRY(secondary_startup_64)
 	/* We come here either from startup_32
 	 * or directly from a 64bit bootloader.
 	 * Since we may have come directly from a bootloader we
arch/x86_64/kernel/setup.c +1 -8
Index: linux/arch/x86_64/kernel/setup.c
===================================================================
@@ -329,15 +329,8 @@ void __init setup_arch(char **cmdline_p)
 #endif
 
 #ifdef CONFIG_SMP
-	/*
-	 * But first pinch a few for the stack/trampoline stuff
-	 * FIXME: Don't need the extra page at 4K, but need to fix
-	 * trampoline before removing it. (see the GDT stuff)
-	 */
-	reserve_bootmem_generic(PAGE_SIZE, PAGE_SIZE);
-
 	/* Reserve SMP trampoline */
-	reserve_bootmem_generic(SMP_TRAMPOLINE_BASE, PAGE_SIZE);
+	reserve_bootmem_generic(SMP_TRAMPOLINE_BASE, 2*PAGE_SIZE);
 #endif
 
 #ifdef CONFIG_ACPI_SLEEP
arch/x86_64/kernel/trampoline.S +154 -14

213 lines not on this page · raw message

#22 lore raw

Re: [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Andi Kleen
Quoted 7 lines · Andi Kleen

From: Vivek Goyal <[email protected]>

o Extend the bzImage protocol (same as i386) to allow bzImage loaders to load the protected mode kernel at non-1MB address. Now protected mode component is relocatable and can be loaded at non-1MB addresses.

Quoted 6 lines

o As of today kdump uses it to run a second kernel from a reserved memory area.

Can you point to / link to threads where the bootloader folks looked over the reloc changes from their side, and commented?

Jeff

author
#23 lore raw

Re: [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 3 lines

Can you point to / link to threads where the bootloader folks looked over the reloc changes from their side, and commented?

What boot loader folks? The result still works with grub and pxelinux at least and I guess the others will complain as they get around testing new kernels.

-Andi

#24 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeff Garzik
Quoted 11 lines · Jeff Garzik
Quoted 10 lines · Andi Kleen

From: Vivek Goyal <[email protected]>

o Extend the bzImage protocol (same as i386) to allow bzImage loaders to load the protected mode kernel at non-1MB address. Now protected mode component is relocatable and can be loaded at non-1MB addresses.

o As of today kdump uses it to run a second kernel from a reserved memory area.

Quoted 6 lines
Quoted 3 lines

Can you point to / link to threads where the bootloader folks looked over the reloc changes from their side, and commented?

Jeff what is your concern.

The boot protocol change is in 2.6.21 for arch/i386.

HPA looked at it a while ago.

All it does is set a flag that tells a bootloader.
"Hey. I can run when loaded a non-default address, and this is what
you have to align me to."

All relocation processing happens in the kernel itself.

So it is all pretty trivial.

Eric

#25 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 5 lines · Eric W. Biederman

The boot protocol change is in 2.6.21 for arch/i386.

HPA looked at it a while ago.

Quoted 8 lines

All it does is set a flag that tells a bootloader.
"Hey. I can run when loaded a non-default address, and this is what
you have to align me to."

All relocation processing happens in the kernel itself.

So it is all pretty trivial.

Indeed. We *did* find some problems with Grub with the early versions, those were addressed.

-hpa

#28 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman

No specific concern; the patch description did not say that bootloader people had ACK'd the change, or describe the testing regimen.

Just reading the patch, the impact and preparation were unknowns.

Jeff

#26 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 10 lines · H. Peter Anvin
Quoted 9 lines · Eric W. Biederman

The boot protocol change is in 2.6.21 for arch/i386.

HPA looked at it a while ago.

All it does is set a flag that tells a bootloader.
"Hey. I can run when loaded a non-default address, and this is what
you have to align me to."

Quoted 7 lines
Quoted 4 lines

All relocation processing happens in the kernel itself.

So it is all pretty trivial.

Indeed. We *did* find some problems with Grub with the early versions, those were addressed.

We found some failures that weren't root caused so we went to this more conservative version.

RHEL5 is actually shipping the original version of these patches if I recall correctly.

Eric

#27 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 17 lines · Eric W. Biederman
Quoted 15 lines · H. Peter Anvin
Quoted 13 lines · Eric W. Biederman

The boot protocol change is in 2.6.21 for arch/i386.

HPA looked at it a while ago.

All it does is set a flag that tells a bootloader.
"Hey. I can run when loaded a non-default address, and this is what
you have to align me to."

All relocation processing happens in the kernel itself.

So it is all pretty trivial.

Quoted 9 lines
Quoted 2 lines

Indeed. We *did* find some problems with Grub with the early versions, those were addressed.

We found some failures that weren't root caused so we went to this more conservative version.

RHEL5 is actually shipping the original version of these patches if I recall correctly.

Yes, RHEL5 is shipping original version of patches where an where and ELF header has been added to describe bzImage.

Thanks
Vivek

#29 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 6 lines · Eric W. Biederman

All it does is set a flag that tells a bootloader.
"Hey. I can run when loaded a non-default address, and this is what
you have to align me to."

All relocation processing happens in the kernel itself.

Is it possible to decompress and extract the kernel image from the bzImage without executing it? Ie, is there enough information to find the compressed data part of the bzImage by inspection?

At some point we'll need to change the Xen domain builder to handle bzImage files, and it would be best if we didn't need to run them.

J

#30 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 8 lines · Jeremy Fitzhardinge
Quoted 6 lines · Eric W. Biederman

All it does is set a flag that tells a bootloader.
"Hey. I can run when loaded a non-default address, and this is what
you have to align me to."

All relocation processing happens in the kernel itself.

Quoted 6 lines

Is it possible to decompress and extract the kernel image from the bzImage without executing it? Ie, is there enough information to find the compressed data part of the bzImage by inspection?

At some point we'll need to change the Xen domain builder to handle bzImage files, and it would be best if we didn't need to run them.

/sbin/kexec bzImage ....

There is a 32bit entry point that is reasonably well specified you can use. I'm guessing you want to recover the 64bit ELF, with all of your nice ELF notes etc. vmlinux is run through "objcopy -O binary" as part of the bzImage build process so all of the ELF metadata is lost.

I have several ideas on how we can make this work but first I have to ask what is it that you are trying to accomplish?

<rant>
Right now I'm a little frustrated that insanity below slipped into head.S right after the 32bit entry point after the review said use the normal linux parameters for parameter passing.

Quoted 5 lines

#ifdef CONFIG_PARAVIRT
movl %cs, %eax
testl $0x3, %eax
jnz startup_paravirt
#endif

The whole thing should be based on a value in the linux parameter block pointed to by %esi, instead of the insane preserve all registers and attempt to be super compatible with everyone.

Yes we do need a branch there, but no we don't need to be changing the format we pass arguments to the kernel in.
</rant>

Anyway since it seems there is interest in going farther in tweaking the linux boot process let's open thread up to what is needed/wanted for future enhancements to linux booting, and let's see if we can design something that works and isn't brain dead.

Eric

#198 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 8 lines · Jeremy Fitzhardinge
Quoted 6 lines · Eric W. Biederman

All it does is set a flag that tells a bootloader.
"Hey. I can run when loaded a non-default address, and this is what
you have to align me to."

All relocation processing happens in the kernel itself.

Quoted 7 lines

Is it possible to decompress and extract the kernel image from the bzImage without executing it? Ie, is there enough information to find the compressed data part of the bzImage by inspection?

At some point we'll need to change the Xen domain builder to handle bzImage files, and it would be best if we didn't need to run them.

Probabilistically, you might be able to (search for a gzip header), but it is *definitely* not guaranteed by protocol.

-hpa

#199 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 13 lines · H. Peter Anvin
Quoted 12 lines · Jeremy Fitzhardinge
Quoted 6 lines · Eric W. Biederman

All it does is set a flag that tells a bootloader.
"Hey. I can run when loaded a non-default address, and this is what
you have to align me to."

All relocation processing happens in the kernel itself.

Is it possible to decompress and extract the kernel image from the bzImage without executing it? Ie, is there enough information to find the compressed data part of the bzImage by inspection?

Quoted 6 lines
Quoted 3 lines

At some point we'll need to change the Xen domain builder to handle bzImage files, and it would be best if we didn't need to run them.

Probabilistically, you might be able to (search for a gzip header), but it is *definitely* not guaranteed by protocol.

I suspect the issue isn't so much skipping the decompression
but either getting at the Xen ELF notes or bypassing privileged instructions.

Eric

#31 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 10 lines · Eric W. Biederman

Right now I'm a little frustrated that insanity below slipped into head.S right after the 32bit entry point after the review said use the normal linux parameters for parameter passing.

Quoted 5 lines

#ifdef CONFIG_PARAVIRT
movl %cs, %eax
testl $0x3, %eax
jnz startup_paravirt
#endif

Quoted 3 lines

The whole thing should be based on a value in the linux parameter block pointed to by %esi, instead of the insane preserve all registers and attempt to be super compatible with everyone.

Dammit, Eric, you spend a lot of time using words like "insane" where you mean we didn't do everything all at once.

It's *not* clear that using %esi is sane, but nothing in the current code prevents that.

I was trying to get Xen to use this entry point rather than their own: I failed, and only lguest now uses it.

Fortunately, this also means it's trivial to change. Rusty.

#32 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 10 lines · Eric W. Biederman

Right now I'm a little frustrated that insanity below slipped into head.S right after the 32bit entry point after the review said use the normal linux parameters for parameter passing.

Quoted 5 lines

#ifdef CONFIG_PARAVIRT
movl %cs, %eax
testl $0x3, %eax
jnz startup_paravirt
#endif

Quoted 3 lines

The whole thing should be based on a value in the linux parameter block pointed to by %esi, instead of the insane preserve all registers and attempt to be super compatible with everyone.

Dammit, Eric, you spend a lot of time using words like "insane" where you mean we didn't do everything all at once.

It's *not* clear that using %esi is sane, but nothing in the current code prevents that.

I was trying to get Xen to use this entry point rather than their own: I failed, and only lguest now uses it.

Fortunately, this also means it's trivial to change. Rusty.

#33 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 7 lines · Rusty Russell

Dammit, Eric, you spend a lot of time using words like "insane" where you mean we didn't do everything all at once.

It's *not* clear that using %esi is sane, but nothing in the current code prevents that.

Why not?

-hpa

#200 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 6 lines · Jeremy Fitzhardinge

Is it possible to decompress and extract the kernel image from the bzImage without executing it? Ie, is there enough information to find the compressed data part of the bzImage by inspection?

At some point we'll need to change the Xen domain builder to handle bzImage files, and it would be best if we didn't need to run them.

Almost. See lguest's launcher code: load_bzimage(). You'll hate it 8)

Rusty.

#34 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 9 lines · H. Peter Anvin
Quoted 6 lines · Rusty Russell

Dammit, Eric, you spend a lot of time using words like "insane" where you mean we didn't do everything all at once.

It's *not* clear that using %esi is sane, but nothing in the current code prevents that.

Why not?

(I assume you mean why isn't it clear?)

Because VMI uses the presence of a ROM to indicate it's not native. KVM uses a magic MSR IIRC.

I think it makes sense for lguest to change over, tho. Patches welcome
8)

Rusty.

#35 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 9 lines · H. Peter Anvin
Quoted 6 lines · Rusty Russell

Dammit, Eric, you spend a lot of time using words like "insane" where you mean we didn't do everything all at once.

It's *not* clear that using %esi is sane, but nothing in the current code prevents that.

Why not?

(I assume you mean why isn't it clear?)

Because VMI uses the presence of a ROM to indicate it's not native. KVM uses a magic MSR IIRC.

I think it makes sense for lguest to change over, tho. Patches welcome
8)

Rusty.

#36 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 9 lines · Rusty Russell
Quoted 8 lines · H. Peter Anvin
Quoted 6 lines · Rusty Russell

Dammit, Eric, you spend a lot of time using words like "insane" where you mean we didn't do everything all at once.

It's *not* clear that using %esi is sane, but nothing in the current code prevents that.

Quoted 6 lines
Quoted 1 line

Why not?

(I assume you mean why isn't it clear?)

Because VMI uses the presence of a ROM to indicate it's not native. KVM uses a magic MSR IIRC.

Reasonable, if you don't mid a little hardware emulation.

Quoted 2 lines

I think it makes sense for lguest to change over, tho. Patches welcome
8)

Sure.

Peter do we want to use the bootloader byte and assign lguest it's own bootloader type or do we want to add another field specific to paravirtualized environments?

Eric

#40 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Rusty Russell
Quoted 11 lines · Rusty Russell
Quoted 9 lines · H. Peter Anvin
Quoted 6 lines · Rusty Russell

Dammit, Eric, you spend a lot of time using words like "insane" where you mean we didn't do everything all at once.

It's *not* clear that using %esi is sane, but nothing in the current code prevents that.

Why not?

Quoted 7 lines

(I assume you mean why isn't it clear?)

Because VMI uses the presence of a ROM to indicate it's not native. KVM uses a magic MSR IIRC.

I think it makes sense for lguest to change over, tho. Patches welcome
8)

Reading this it occurs to me what I object to wasn't that clear.

I have no problem with the testing of %cs to see if we are not in ring0. That part while a little odd is fine, and we will certainly need a test to skip the protected instructions in head.S

What I object to in particular is having (struct lguest_info?) instead of using the standard format for kernel parameters pointed to in %esi.

Eric

#41 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Rusty Russell
Quoted 11 lines · Rusty Russell
Quoted 9 lines · H. Peter Anvin
Quoted 6 lines · Rusty Russell

Dammit, Eric, you spend a lot of time using words like "insane" where you mean we didn't do everything all at once.

It's *not* clear that using %esi is sane, but nothing in the current code prevents that.

Why not?

Quoted 7 lines

(I assume you mean why isn't it clear?)

Because VMI uses the presence of a ROM to indicate it's not native. KVM uses a magic MSR IIRC.

I think it makes sense for lguest to change over, tho. Patches welcome
8)

Reading this it occurs to me what I object to wasn't that clear.

I have no problem with the testing of %cs to see if we are not in ring0. That part while a little odd is fine, and we will certainly need a test to skip the protected instructions in head.S

What I object to in particular is having (struct lguest_info?) instead of using the standard format for kernel parameters pointed to in %esi.

Eric

#37 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 7 lines · Eric W. Biederman

Sure.

Peter do we want to use the bootloader byte and assign lguest it's own bootloader type or do we want to add another field specific to paravirtualized environments?

The bootloader byte is already a bit too overused; I'm a little scared that we're going to run out of boot loader IDs as it is.

We probably should add another field, and while we're at it maybe we should add a boot loader extension field.

-hpa

#38 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 7 lines · Eric W. Biederman

Sure.

Peter do we want to use the bootloader byte and assign lguest it's own bootloader type or do we want to add another field specific to paravirtualized environments?

The bootloader byte is already a bit too overused; I'm a little scared that we're going to run out of boot loader IDs as it is.

We probably should add another field, and while we're at it maybe we should add a boot loader extension field.

-hpa

#39 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 9 lines · H. Peter Anvin
Quoted 7 lines · Eric W. Biederman

Sure.

Peter do we want to use the bootloader byte and assign lguest it's own bootloader type or do we want to add another field specific to paravirtualized environments?

Quoted 5 lines

The bootloader byte is already a bit too overused; I'm a little scared that we're going to run out of boot loader IDs as it is.

We probably should add another field, and while we're at it maybe we should add a boot loader extension field.

A dedicated subarchitecture field would make sense. One of the pieces that would be nice is if we could detect other non paravirt subarchitectures.

James is there a reasonable way to detect voyager at boot time? So we could potentially have a generic kernel that can also boot on voyager?

Eric

#61 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 3 lines · Eric W. Biederman

I have several ideas on how we can make this work but first I have to ask what is it that you are trying to accomplish?

The requirements are:

1. the domain builder needs to get various information about the guest kernel by inspecting its ELF notes
2. we start the kernel in 32-bit mode with paging enabled, in ring 1
3. the guest kernel needs various pieces of runtime information from the hypervisor about its runtime environment

At the moment we just load a bare vmlinux kernel with a xen-specific entrypoint, so 1 and 2 are easy. 3 is achieved by having the domain builder start the kernel with %esi pointing to a Xen info structure which tells the kernel what it needs to know.

That works OK for a kernel which is compiled to run under Xen and can't run in any other environment, but now that we can generate a single kernel which can run in any number of different environments, its unfortunate that we still need multiple variants of the kernel image.

Clearly the Xen domain builder needs to be extended to deal with a bzImage format kernel directly, so we can use the same actual kernel image for native and Xen booting. Since we're changing the domain builder anyway, I can change the details of how it works so long as the 3 requirements can still be met.

So, I have no problem in also building a boot protocol info structure, and passing that in %esi, so long as I can store a pointer to the Xen-specific info as well. Some info will be duplicated, like the initrd location, but that's OK.

I'd already reserved a Xen bootloader ID specifically with this in mind; all I really need is a place where I can stash the pointer.

I think I'd prefer to have the domain builder decompress/relocate the kernel from the bzImage and start it directly, rather than have it decompress/relocate itself, but I'm not really set on that. It depends on how well it can deal with having paging enabled and being in ring 1. Looks like it might just be a matter of starting up with "enough" memory mapped.

So the biggest unknown is where to put the Xen ELF notes.

J

#62 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 18 lines · Jeremy Fitzhardinge
Quoted 3 lines · Eric W. Biederman

I have several ideas on how we can make this work but first I have to ask what is it that you are trying to accomplish?

The requirements are:

1. the domain builder needs to get various information about the guest kernel by inspecting its ELF notes
2. we start the kernel in 32-bit mode with paging enabled, in ring 1
3. the guest kernel needs various pieces of runtime information from the hypervisor about its runtime environment

At the moment we just load a bare vmlinux kernel with a xen-specific entrypoint, so 1 and 2 are easy. 3 is achieved by having the domain builder start the kernel with %esi pointing to a Xen info structure which tells the kernel what it needs to know.

Quoted 4 lines

That works OK for a kernel which is compiled to run under Xen and can't run in any other environment, but now that we can generate a single kernel which can run in any number of different environments, its unfortunate that we still need multiple variants of the kernel image.

Yes.

Quoted 5 lines

Clearly the Xen domain builder needs to be extended to deal with a bzImage format kernel directly, so we can use the same actual kernel image for native and Xen booting. Since we're changing the domain builder anyway, I can change the details of how it works so long as the 3 requirements can still be met.

Ok.

Quoted 4 lines

So, I have no problem in also building a boot protocol info structure, and passing that in %esi, so long as I can store a pointer to the Xen-specific info as well. Some info will be duplicated, like the initrd location, but that's OK.

Reasonable.

Quoted 2 lines

I'd already reserved a Xen bootloader ID specifically with this in mind; all I really need is a place where I can stash the pointer.

Right.

So if you are using the standard linux kernel calling convention and placing the standard arguments in %esi supporting bzImage gets easier.

Quoted 3 lines

I think I'd prefer to have the domain builder decompress/relocate the kernel from the bzImage and start it directly, rather than have it decompress/relocate itself, but I'm not really set on that.

We can change a lot more implementation details arbitrarily if you don't know what needs to happen for decompression and relocation. Although I think there is a reasonable argument to support a bImage format. bzImage without compression. The current bootloaders would not care but in the embedded space you can save space but not including the decompressor in the kernel.

We have to avoid the writes decompressor-prinnt routines and possibly the reload of the segment registers. But otherwise we should be fine. I don't see any other privileged instructions in arch/i386/boot/compressed/{head.S, misc.c}

Quoted 4 lines

It depends
on how well it can deal with having paging enabled and being in ring 1. Looks like it might just be a matter of starting up with "enough" memory mapped.

Yes. I think so. There is an additional issue of exactly how do we get the fixmap region allocated so we can use it but that is minor.

Quoted 1 line

So the biggest unknown is where to put the Xen ELF notes.

What I really want to do is go back to sticking an ELF header on the bzImage. We still can't support multiple entry points that way but we can include ELF notes fairly easily.

It looks like for the next version of booting lguest and Xen are actually coming closer together again. Yea.

For boot protocol. 2.0.7 We currently need a subarchitecture field (16bits?). default == 0, Xen, lguest, voyager?, visws?, numaq?, efi?

We need a subarchitecture data pointer field (32bits).

We need some subarchitecture kernel information for the different bootloader.

We need to target .23 because it is to late for .22.

Eric

#63 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 18 lines · Jeremy Fitzhardinge
Quoted 3 lines · Eric W. Biederman

I have several ideas on how we can make this work but first I have to ask what is it that you are trying to accomplish?

The requirements are:

1. the domain builder needs to get various information about the guest kernel by inspecting its ELF notes
2. we start the kernel in 32-bit mode with paging enabled, in ring 1
3. the guest kernel needs various pieces of runtime information from the hypervisor about its runtime environment

At the moment we just load a bare vmlinux kernel with a xen-specific entrypoint, so 1 and 2 are easy. 3 is achieved by having the domain builder start the kernel with %esi pointing to a Xen info structure which tells the kernel what it needs to know.

Quoted 4 lines

That works OK for a kernel which is compiled to run under Xen and can't run in any other environment, but now that we can generate a single kernel which can run in any number of different environments, its unfortunate that we still need multiple variants of the kernel image.

Yes.

Quoted 5 lines

Clearly the Xen domain builder needs to be extended to deal with a bzImage format kernel directly, so we can use the same actual kernel image for native and Xen booting. Since we're changing the domain builder anyway, I can change the details of how it works so long as the 3 requirements can still be met.

Ok.

Quoted 4 lines

So, I have no problem in also building a boot protocol info structure, and passing that in %esi, so long as I can store a pointer to the Xen-specific info as well. Some info will be duplicated, like the initrd location, but that's OK.

Reasonable.

Quoted 2 lines

I'd already reserved a Xen bootloader ID specifically with this in mind; all I really need is a place where I can stash the pointer.

Right.

So if you are using the standard linux kernel calling convention and placing the standard arguments in %esi supporting bzImage gets easier.

Quoted 3 lines

I think I'd prefer to have the domain builder decompress/relocate the kernel from the bzImage and start it directly, rather than have it decompress/relocate itself, but I'm not really set on that.

We can change a lot more implementation details arbitrarily if you don't know what needs to happen for decompression and relocation. Although I think there is a reasonable argument to support a bImage format. bzImage without compression. The current bootloaders would not care but in the embedded space you can save space but not including the decompressor in the kernel.

We have to avoid the writes decompressor-prinnt routines and possibly the reload of the segment registers. But otherwise we should be fine. I don't see any other privileged instructions in arch/i386/boot/compressed/{head.S, misc.c}

Quoted 4 lines

It depends
on how well it can deal with having paging enabled and being in ring 1. Looks like it might just be a matter of starting up with "enough" memory mapped.

Yes. I think so. There is an additional issue of exactly how do we get the fixmap region allocated so we can use it but that is minor.

Quoted 1 line

So the biggest unknown is where to put the Xen ELF notes.

What I really want to do is go back to sticking an ELF header on the bzImage. We still can't support multiple entry points that way but we can include ELF notes fairly easily.

It looks like for the next version of booting lguest and Xen are actually coming closer together again. Yea.

For boot protocol. 2.0.7 We currently need a subarchitecture field (16bits?). default == 0, Xen, lguest, voyager?, visws?, numaq?, efi?

We need a subarchitecture data pointer field (32bits).

We need some subarchitecture kernel information for the different bootloader.

We need to target .23 because it is to late for .22.

Eric

#64 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 7 lines · Eric W. Biederman
Quoted 4 lines

I think I'd prefer to have the domain builder decompress/relocate the kernel from the bzImage and start it directly, rather than have it decompress/relocate itself, but I'm not really set on that.

We can change a lot more implementation details arbitrarily if you don't know what needs to happen for decompression and relocation.

Yes, and if it can be made to work, it ultimately means less work for me ;)

Quoted 1 line

We have to avoid the writes decompressor-prinnt routines

At worst, we could set up chunk of memory as a dummy framebuffer. That might be useful for debugging anyway.

Quoted 5 lines

and
possibly the reload of the segment registers. But otherwise we should be fine. I don't see any other privileged instructions in arch/i386/boot/compressed/{head.S, misc.c}

Xen will start the domain with a GDT loaded, and all the segment registers loaded with flat segments. I guess boot/compressed/head.S could do the %cs ring check before deciding to do privileged operations.

I presume bzImage jumps straight to startup_32 on the newly decompressed kernel?

Quoted 9 lines
Quoted 5 lines

It depends
on how well it can deal with having paging enabled and being in ring 1. Looks like it might just be a matter of starting up with "enough" memory mapped.

Yes. I think so. There is an additional issue of exactly how do we get the fixmap region allocated so we can use it but that is minor.

I haven't checked if it already has this, but it would be nice if the bzImage had a memory range/list of memory ranges it needs mapped to get the kernel on its feet, so that the domain builder can just go and map those areas for it (either P==V mappings, or with a constant offset; whichever is more useful).

Also, if its a PAE kernel, Xen will start with PAE mode enabled, so bzImage will have to deal with that. But if its not touching pagetables, it won't matter.

Quoted 4 lines

What I really want to do is go back to sticking an ELF header on the bzImage. We still can't support multiple entry points that way but we can include ELF notes fairly easily.

That's OK. We'll be able to use the boot info to go into the Xen-specific path shortly after startup_32 anyway.

BTW, the test for a non-ring 0 %cs won't always be a good test for paravirtualization; we're likely to start seeing hybrid execution models where we run a largely paravirtualized kernel in a SVM/VT container. If we can just unconditionally use the bootloader arch definition to determine the entry path into the kernel, it will clean things up nicely.

Quoted 8 lines

It looks like for the next version of booting lguest and Xen are actually coming closer together again. Yea.

For boot protocol. 2.0.7 We currently need a subarchitecture field (16bits?). default == 0, Xen, lguest, voyager?, visws?, numaq?, efi?

We need a subarchitecture data pointer field (32bits).

Do we want to support starting a 64-bit guest in 64-bit mode?

Quoted 1 line

We need to target .23 because it is to late for .22.

Yes. I'll need to do a moderate amount of work on the Xen side to make this work, I think.

J

#74 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 7 lines · Eric W. Biederman
Quoted 4 lines

I think I'd prefer to have the domain builder decompress/relocate the kernel from the bzImage and start it directly, rather than have it decompress/relocate itself, but I'm not really set on that.

We can change a lot more implementation details arbitrarily if you don't know what needs to happen for decompression and relocation.

Yes, and if it can be made to work, it ultimately means less work for me ;)

Quoted 1 line

We have to avoid the writes decompressor-prinnt routines

At worst, we could set up chunk of memory as a dummy framebuffer. That might be useful for debugging anyway.

Quoted 5 lines

and
possibly the reload of the segment registers. But otherwise we should be fine. I don't see any other privileged instructions in arch/i386/boot/compressed/{head.S, misc.c}

Xen will start the domain with a GDT loaded, and all the segment registers loaded with flat segments. I guess boot/compressed/head.S could do the %cs ring check before deciding to do privileged operations.

I presume bzImage jumps straight to startup_32 on the newly decompressed kernel?

Quoted 9 lines
Quoted 5 lines

It depends
on how well it can deal with having paging enabled and being in ring 1. Looks like it might just be a matter of starting up with "enough" memory mapped.

Yes. I think so. There is an additional issue of exactly how do we get the fixmap region allocated so we can use it but that is minor.

I haven't checked if it already has this, but it would be nice if the bzImage had a memory range/list of memory ranges it needs mapped to get the kernel on its feet, so that the domain builder can just go and map those areas for it (either P==V mappings, or with a constant offset; whichever is more useful).

Also, if its a PAE kernel, Xen will start with PAE mode enabled, so bzImage will have to deal with that. But if its not touching pagetables, it won't matter.

Quoted 4 lines

What I really want to do is go back to sticking an ELF header on the bzImage. We still can't support multiple entry points that way but we can include ELF notes fairly easily.

That's OK. We'll be able to use the boot info to go into the Xen-specific path shortly after startup_32 anyway.

BTW, the test for a non-ring 0 %cs won't always be a good test for paravirtualization; we're likely to start seeing hybrid execution models where we run a largely paravirtualized kernel in a SVM/VT container. If we can just unconditionally use the bootloader arch definition to determine the entry path into the kernel, it will clean things up nicely.

Quoted 8 lines

It looks like for the next version of booting lguest and Xen are actually coming closer together again. Yea.

For boot protocol. 2.0.7 We currently need a subarchitecture field (16bits?). default == 0, Xen, lguest, voyager?, visws?, numaq?, efi?

We need a subarchitecture data pointer field (32bits).

Do we want to support starting a 64-bit guest in 64-bit mode?

Quoted 1 line

We need to target .23 because it is to late for .22.

Yes. I'll need to do a moderate amount of work on the Xen side to make this work, I think.

J

#65 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 6 lines · Jeremy Fitzhardinge

I haven't checked if it already has this, but it would be nice if the bzImage had a memory range/list of memory ranges it needs mapped to get the kernel on its feet, so that the domain builder can just go and map those areas for it (either P==V mappings, or with a constant offset; whichever is more useful).

Of course if it were a properly formed ELF file, you could encode this in the PHDRs.

J

#66 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 6 lines · Jeremy Fitzhardinge

I haven't checked if it already has this, but it would be nice if the bzImage had a memory range/list of memory ranges it needs mapped to get the kernel on its feet, so that the domain builder can just go and map those areas for it (either P==V mappings, or with a constant offset; whichever is more useful).

Of course if it were a properly formed ELF file, you could encode this in the PHDRs.

J

#67 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 11 lines · Jeremy Fitzhardinge
Quoted 7 lines · Eric W. Biederman
Quoted 4 lines

I think I'd prefer to have the domain builder decompress/relocate the kernel from the bzImage and start it directly, rather than have it decompress/relocate itself, but I'm not really set on that.

We can change a lot more implementation details arbitrarily if you don't know what needs to happen for decompression and relocation.

Yes, and if it can be made to work, it ultimately means less work for me ;)

Now you are beginning to sound like a bootloader author. Make it work and forget about it :)

Quoted 4 lines
Quoted 1 line

We have to avoid the writes decompressor-prinnt routines

At worst, we could set up chunk of memory as a dummy framebuffer. That might be useful for debugging anyway.

I'm trying to recall how we handle this on the LinuxBIOS side. Because we have machines without a framebuffer setup. Oh yeah, we started in 32bit mode...

I do have some parameters to parse the command line in misc.c that would accomplish this goal.

Quoted 10 lines
Quoted 5 lines

and
possibly the reload of the segment registers. But otherwise we should be fine. I don't see any other privileged instructions in arch/i386/boot/compressed/{head.S, misc.c}

Xen will start the domain with a GDT loaded, and all the segment registers loaded with flat segments. I guess boot/compressed/head.S could do the %cs ring check before deciding to do privileged operations.

I'm tempted to just reload the segments in setup.S, but that might break loadlin support or one of the other bootloaders that starts the kernel in 32bit mode so we need to be careful.

Quoted 2 lines

I presume bzImage jumps straight to startup_32 on the newly decompressed kernel?

Straight isn't the way I would but it but yes. startup_32 in arch/i386/head.S is the first piece of code that outside of the decompressor that it runs.

Quoted 5 lines

I haven't checked if it already has this, but it would be nice if the bzImage had a memory range/list of memory ranges it needs mapped to get the kernel on its feet, so that the domain builder can just go and map those areas for it (either P==V mappings, or with a constant offset; whichever is more useful).

P==V mappings I suspect.

Quoted 3 lines

Also, if its a PAE kernel, Xen will start with PAE mode enabled, so bzImage will have to deal with that. But if its not touching pagetables, it won't matter.

Exactly.

Quoted 7 lines
Quoted 4 lines

What I really want to do is go back to sticking an ELF header on the bzImage. We still can't support multiple entry points that way but we can include ELF notes fairly easily.

That's OK. We'll be able to use the boot info to go into the Xen-specific path shortly after startup_32 anyway.

Yes.

Quoted 5 lines

BTW, the test for a non-ring 0 %cs won't always be a good test for paravirtualization; we're likely to start seeing hybrid execution models where we run a largely paravirtualized kernel in a SVM/VT container. If we can just unconditionally use the bootloader arch definition to determine the entry path into the kernel, it will clean things up nicely.

Yes. That is why we need a distinct field for this and not overloading the bootloader id. That way if the field is non-zero we need to do something special.

Quoted 10 lines
Quoted 8 lines

It looks like for the next version of booting lguest and Xen are actually coming closer together again. Yea.

For boot protocol. 2.0.7 We currently need a subarchitecture field (16bits?). default == 0, Xen, lguest, voyager?, visws?, numaq?, efi?

We need a subarchitecture data pointer field (32bits).

Do we want to support starting a 64-bit guest in 64-bit mode?

It's the only way that will be sane. When I was doing my ELF header on bzImage work I had that working. But it got dropped due to some unexplained, unreproducible testing failures and not really being necessary at the time. We also need that if we want to be certain we don't play with page tables.

The other thing the ELF headers gave was a precise accounting of where the kernel was, which is essentially what needs to be mapped at boot time.

The hard part I suspect is going to be handling Xen when setup the physical == virtual page tables

Quoted 4 lines
Quoted 1 line

We need to target .23 because it is to late for .22.

Yes. I'll need to do a moderate amount of work on the Xen side to make this work, I think.

I think we all will but the upside if we design this carefully is something that we won't have to change.

Eric

#68 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 11 lines · Jeremy Fitzhardinge
Quoted 7 lines · Eric W. Biederman
Quoted 4 lines

I think I'd prefer to have the domain builder decompress/relocate the kernel from the bzImage and start it directly, rather than have it decompress/relocate itself, but I'm not really set on that.

We can change a lot more implementation details arbitrarily if you don't know what needs to happen for decompression and relocation.

Yes, and if it can be made to work, it ultimately means less work for me ;)

Now you are beginning to sound like a bootloader author. Make it work and forget about it :)

Quoted 4 lines
Quoted 1 line

We have to avoid the writes decompressor-prinnt routines

At worst, we could set up chunk of memory as a dummy framebuffer. That might be useful for debugging anyway.

I'm trying to recall how we handle this on the LinuxBIOS side. Because we have machines without a framebuffer setup. Oh yeah, we started in 32bit mode...

I do have some parameters to parse the command line in misc.c that would accomplish this goal.

Quoted 10 lines
Quoted 5 lines

and
possibly the reload of the segment registers. But otherwise we should be fine. I don't see any other privileged instructions in arch/i386/boot/compressed/{head.S, misc.c}

Xen will start the domain with a GDT loaded, and all the segment registers loaded with flat segments. I guess boot/compressed/head.S could do the %cs ring check before deciding to do privileged operations.

I'm tempted to just reload the segments in setup.S, but that might break loadlin support or one of the other bootloaders that starts the kernel in 32bit mode so we need to be careful.

Quoted 2 lines

I presume bzImage jumps straight to startup_32 on the newly decompressed kernel?

Straight isn't the way I would but it but yes. startup_32 in arch/i386/head.S is the first piece of code that outside of the decompressor that it runs.

Quoted 5 lines

I haven't checked if it already has this, but it would be nice if the bzImage had a memory range/list of memory ranges it needs mapped to get the kernel on its feet, so that the domain builder can just go and map those areas for it (either P==V mappings, or with a constant offset; whichever is more useful).

P==V mappings I suspect.

Quoted 3 lines

Also, if its a PAE kernel, Xen will start with PAE mode enabled, so bzImage will have to deal with that. But if its not touching pagetables, it won't matter.

Exactly.

Quoted 7 lines
Quoted 4 lines

What I really want to do is go back to sticking an ELF header on the bzImage. We still can't support multiple entry points that way but we can include ELF notes fairly easily.

That's OK. We'll be able to use the boot info to go into the Xen-specific path shortly after startup_32 anyway.

Yes.

Quoted 5 lines

BTW, the test for a non-ring 0 %cs won't always be a good test for paravirtualization; we're likely to start seeing hybrid execution models where we run a largely paravirtualized kernel in a SVM/VT container. If we can just unconditionally use the bootloader arch definition to determine the entry path into the kernel, it will clean things up nicely.

Yes. That is why we need a distinct field for this and not overloading the bootloader id. That way if the field is non-zero we need to do something special.

Quoted 10 lines
Quoted 8 lines

It looks like for the next version of booting lguest and Xen are actually coming closer together again. Yea.

For boot protocol. 2.0.7 We currently need a subarchitecture field (16bits?). default == 0, Xen, lguest, voyager?, visws?, numaq?, efi?

We need a subarchitecture data pointer field (32bits).

Do we want to support starting a 64-bit guest in 64-bit mode?

It's the only way that will be sane. When I was doing my ELF header on bzImage work I had that working. But it got dropped due to some unexplained, unreproducible testing failures and not really being necessary at the time. We also need that if we want to be certain we don't play with page tables.

The other thing the ELF headers gave was a precise accounting of where the kernel was, which is essentially what needs to be mapped at boot time.

The hard part I suspect is going to be handling Xen when setup the physical == virtual page tables

Quoted 4 lines
Quoted 1 line

We need to target .23 because it is to late for .22.

Yes. I'll need to do a moderate amount of work on the Xen side to make this work, I think.

I think we all will but the upside if we design this carefully is something that we won't have to change.

Eric

#69 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 5 lines · Eric W. Biederman

I'm tempted to just reload the segments in setup.S, but that might break loadlin support or one of the other bootloaders that starts the kernel in 32bit mode so we need to be careful.

We already load all the segments in setup.S. I'm retaining this in my rewrite.

Given that I'm rewriting the whole thing, if there are things you want setup.S to do, now is the time to ask.

-hpa

#70 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 9 lines · H. Peter Anvin
Quoted 5 lines · Eric W. Biederman

I'm tempted to just reload the segments in setup.S, but that might break loadlin support or one of the other bootloaders that starts the kernel in 32bit mode so we need to be careful.

We already load all the segments in setup.S. I'm retaining this in my rewrite.

Good. I guess I had moved it there in my last cleanup but I wasn't brave enough yet to remove the reloads from both version of head.S yet.

We should probably load the segment registers in trampoline.S as well that would simplify things a little bit.

Quoted 2 lines

Given that I'm rewriting the whole thing, if there are things you want setup.S to do, now is the time to ask.

The big wish list item would be subarch detection (at least if we need it early). As we are quickly moving to infrastructure that can runtime switch between subarch's if we can detect the difference.

For the paravirt subarchitectures we are actually going to skip past setup.S

So the big thing we need to start doing is to document the 32bit entry point and what can be expected of it etc, especially in the paravirt context. But that isn't a setup.S problem.

Oh. Yes. We need a parameter structure in the kernel, that documents what %esi points to later. What arguments can be found in the bootloader data. If you are playing with setup.S in C that tends to be a setup.S function.

Andi already has a call to verify_cpu so we abort if the cpu can't handle our current kernel. While that is not perfect aborting gracefully in setup.S is a lot better then a lot of the alternatives.

Mostly what we need is to sort through the requirements of this next boot protocol revision for paravirt loaders so we can do that cleanly. It will probably need a subarch type field and a subarch data pointer field, but except for being stored in Setup.S that isn't much of a setup.S problem either.

Eric

author
#71 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 9 lines · H. Peter Anvin
Quoted 5 lines · Eric W. Biederman

I'm tempted to just reload the segments in setup.S, but that might break loadlin support or one of the other bootloaders that starts the kernel in 32bit mode so we need to be careful.

We already load all the segments in setup.S. I'm retaining this in my rewrite.

It's still unclear to me why exactly you want to rewrite it? Are there any particular bugs in the current code you want to fix?

-Andi

#72 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 4 lines · Andi Kleen

It's still unclear to me why exactly you want to rewrite it? Are there any particular bugs in the current code you want to fix?

It's more the sheer degree of unmaintainability which is grating on my nerves. There is way too much hocus-pocus going on, and I dare to say that probably noone understands what actually happens in there.

In response to the question about what the code looks like, I have put a development snapshot patch at:

http://userweb.kernel.org/~hpa/setup-snapshot-2007.04.30.patch

Note that it compiles, but it doesn't work yet. This is not a submission, just a "what does the code actually look like" sample.

-hpa

#42 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 8 lines · Eric W. Biederman

Reading this it occurs to me what I object to wasn't that clear.

I have no problem with the testing of %cs to see if we are not in ring0. That part while a little odd is fine, and we will certainly need a test to skip the protected instructions in head.S

What I object to in particular is having (struct lguest_info?) instead of using the standard format for kernel parameters pointed to in %esi.

Here's a rough patch to see what it looks like from an lguest POV. It's an improvement in many ways: I chose to hardcode the search for matching backend rather than use paravirt_probe-style magic.

It'd be nicer if there were a "struct boot_params" declaration, but we can't have everything.

Cheers,
Rusty.

Documentation/lguest/lguest.c +20 -9
diff -r 9a673a220ad6 Documentation/lguest/lguest.c
@@ -30,10 +30,12 @@
 #include <termios.h>
 #include <getopt.h>
 #include <zlib.h>
+typedef unsigned long long u64;
 typedef uint32_t u32;
 typedef uint16_t u16;
 typedef uint8_t u8;
 #include "../../include/linux/lguest_launcher.h"
+#include "../../include/asm-i386/e820.h"
 
 #define PAGE_PRESENT 0x7 	/* Present, RW, Execute */
 #define NET_PEERNUM 1
@@ -915,10 +917,10 @@ static void usage(void)
 
 int main(int argc, char *argv[])
 {
-	unsigned long mem, pgdir, start, page_offset;
+	unsigned long mem, pgdir, start, page_offset, initrd_size = 0;
 	int c, lguest_fd, waker_fd;
 	struct device_list device_list;
-	struct lguest_boot_info *boot = (void *)0;
+	void *boot = (void *)0;
 	const char *initrd_name = NULL;
 
 	device_list.max_infd = -1;
@@ -966,15 +968,24 @@ int main(int argc, char *argv[])
 	map_device_descriptors(&device_list, mem);
 
 	/* Map the initrd image if requested */
-	if (initrd_name)
-		boot->initrd_size = load_initrd(initrd_name, mem);
+	if (initrd_name) {
+		initrd_size = load_initrd(initrd_name, mem);
+		*(unsigned long *)(boot+0x218) = mem - initrd_size;
+		*(unsigned long *)(boot+0x21c) = initrd_size;
+	}
 
 	/* Set up the initial linar pagetables. */
-	pgdir = setup_pagetables(mem, boot->initrd_size, page_offset);
-
-	/* Give the guest the boot information it needs. */
-	concat(boot->cmdline, argv+optind+2);
-	boot->max_pfn = mem/getpagesize();
+	pgdir = setup_pagetables(mem, initrd_size, page_offset);
+
+	/* E820 memory map: ours is a simple, single region. */
+	*(char*)(boot+E820NR) = 1;
+	*((struct e820entry *)(boot+E820MAP)) 
+		= ((struct e820entry) { 0, mem, E820_RAM });
+	/* Command line pointer and command line (at 4096) */
+	*(void **)(boot + 0x228) = boot + 4096;
+	concat(boot + 4096, argv+optind+2);
+	/* Paravirt type: 1 == lguest */
+	*(int *)(boot + 0x23c) = 1;
 
 	lguest_fd = tell_kernel(pgdir, start, page_offset);
 	waker_fd = setup_waker(&device_list);
arch/i386/kernel/head.S +7 -24
diff -r 9a673a220ad6 arch/i386/kernel/head.S
@@ -504,34 +504,17 @@ ignore_int:
 #ifdef CONFIG_PARAVIRT
 startup_paravirt:
 	cld
+	movl %esi, %eax
+	addl $__PAGE_OFFSET, %eax
  	movl $(init_thread_union+THREAD_SIZE),%esp
 
-	/* We take pains to preserve all the regs. */
-	pushl	%edx
-	pushl	%ecx
-	pushl	%eax
-
-	pushl	$__start_paravirtprobe
-1:
-	movl	0(%esp), %eax
-	cmpl	$__stop_paravirtprobe, %eax
-	je	unhandled_paravirt
-	pushl	(%eax)
-	movl	8(%esp), %eax
-	call	*(%esp)
-	popl	%eax
-
-	movl	4(%esp), %eax
-	movl	8(%esp), %ecx
-	movl	12(%esp), %edx
-
-	addl	$4, (%esp)
-	jmp	1b
-
-unhandled_paravirt:
+#ifdef CONFIG_LGUEST_GUEST
+	cmpl	$1, 0x23c(%eax)
+	je	lguest_init
+#endif
 	/* Nothing wanted us: we're screwed. */
 	ud2
-#endif
+#endif /* CONFIG_PARAVIRT */
 
 /*
  * Real beginning of normal "text" segment
drivers/lguest/lguest.c +9 -14
diff -r 9a673a220ad6 drivers/lguest/lguest.c
@@ -53,7 +53,6 @@ struct lguest_data lguest_data = {
 	.blocked_interrupts = { 1 }, /* Block timer interrupts */
 };
 struct lguest_device_desc *lguest_devices;
-static __initdata const struct lguest_boot_info *boot = __va(0);
 
 static enum paravirt_lazy_mode lazy_mode;
 static void lguest_lazy_mode(enum paravirt_lazy_mode mode)
@@ -378,8 +377,7 @@ static __init char *lguest_memory_setup(
 	/* We do this here because lockcheck barfs if before start_kernel */
 	atomic_notifier_chain_register(&panic_notifier_list, &paniced);
 
-	e820.nr_map = 0;
-	add_memory_region(0, PFN_PHYS(boot->max_pfn), E820_RAM);
+	add_memory_region(E820_MAP->addr, E820_MAP->size, E820_MAP->type);
 	return "LGUEST";
 }
 
@@ -410,8 +408,14 @@ static unsigned lguest_patch(u8 type, u1
 	return insn_len;
 }
 
-__init void lguest_init(void)
-{
+__init void lguest_init(void *boot)
+{
+	/* Copy boot parameters first. */
+	memcpy(boot_params, boot, PARAM_SIZE);
+	memcpy(boot_command_line,
+	       __va(*(unsigned long *)(boot_params + NEW_CL_POINTER)),
+	       COMMAND_LINE_SIZE);
+
 	paravirt_ops.name = "lguest";
 	paravirt_ops.paravirt_enabled = 1;
 	paravirt_ops.kernel_rpl = 1;
@@ -460,7 +464,6 @@ __init void lguest_init(void)
 	paravirt_ops.wbinvd = lguest_wbinvd;
 
 	hcall(LHCALL_LGUEST_INIT, __pa(&lguest_data), 0, 0);
-	strncpy(boot_command_line, boot->cmdline, COMMAND_LINE_SIZE);
 
 	/* We use top of mem for initial pagetables. */
 	init_pg_tables_end = __pa(pg0);
@@ -487,14 +490,6 @@ __init void lguest_init(void)
 
 	add_preferred_console("hvc", 0, NULL);
 
-	if (boot->initrd_size) {
-		/* We stash this at top of memory. */
-		INITRD_START = boot->max_pfn*PAGE_SIZE - boot->initrd_size;
-		INITRD_SIZE = boot->initrd_size;
-		LOADER_TYPE = 0xFF;
-	}
-
 	pm_power_off = lguest_power_off;
 	start_kernel();
 }
-paravirt_probe(lguest_maybe_init);
drivers/lguest/lguest_asm.S +1 -20
diff -r 9a673a220ad6 drivers/lguest/lguest_asm.S
@@ -5,31 +5,12 @@
 /* FIXME: Once asm/processor-flags.h goes in, include that */
 #define X86_EFLAGS_IF 0x00000200
 
-/*
- * This is where we begin: head.S notes that paging is already enabled (which
- * doesn't happen in native boot) and calls the registered paravirt_probe
- * functions one at a time.  Ours is a simple assembler test for magic
- * registers.  If they're correct we jump to lguest_init.
- *
- * We put it in .init.text will be discarded after boot.
- */
-.section .init.text, "ax", @progbits
-ENTRY(lguest_maybe_init)
-	cmpl $LGUEST_MAGIC_EBP, %ebp
-	jne out
-	cmpl $LGUEST_MAGIC_EDI, %edi
-	jne out
-	cmpl $LGUEST_MAGIC_ESI, %esi
-	jne out
-	je lguest_init
-out:
-	ret
-
 /* The templates for inline patching. */
 #define LGUEST_PATCH(name, insns...)			\
 	lgstart_##name:	insns; lgend_##name:;		\
 	.globl lgstart_##name; .globl lgend_##name
 
+.section .init.text, "ax", @progbits
 LGUEST_PATCH(cli, movl $0, lguest_data+LGUEST_DATA_irq_enabled)
 LGUEST_PATCH(sti, movl $X86_EFLAGS_IF, lguest_data+LGUEST_DATA_irq_enabled)
 LGUEST_PATCH(popf, movl %eax, lguest_data+LGUEST_DATA_irq_enabled)
drivers/lguest/lguest_user.c +1 -3
diff -r 9a673a220ad6 drivers/lguest/lguest_user.c
@@ -7,13 +7,11 @@ static void setup_regs(struct lguest_reg
 static void setup_regs(struct lguest_regs *regs, unsigned long start)
 {
 	/* Write out stack in format lguest expects, so we can switch to it. */
-	regs->edi = LGUEST_MAGIC_EDI;
-	regs->ebp = LGUEST_MAGIC_EBP;
-	regs->esi = LGUEST_MAGIC_ESI;
 	regs->ds = regs->es = regs->ss = __KERNEL_DS|GUEST_PL;
 	regs->cs = __KERNEL_CS|GUEST_PL;
 	regs->eflags = 0x202; 	/* Interrupts enabled. */
 	regs->eip = start;
+	/* esi points to our boot information (physical address 0) */
 }
 
 /* + addr */
include/asm-i386/paravirt.h +0 -5
diff -r 9a673a220ad6 include/asm-i386/paravirt.h
@@ -221,11 +221,6 @@ struct paravirt_ops
 	void (*irq_enable_sysexit)(void);
 	void (*iret)(void);
 };
-
-/* Mark a paravirt probe function. */
-#define paravirt_probe(fn)						\
- static asmlinkage void (*__paravirtprobe_##fn)(void) __attribute_used__ \
-		__attribute__((__section__(".paravirtprobe"))) = fn
 
 extern struct paravirt_ops paravirt_ops;
 
include/linux/lguest.h +0 -5
diff -r 9a673a220ad6 include/linux/lguest.h
@@ -2,11 +2,6 @@
  * this is subject to wild and random change between versions. */
 #ifndef _ASM_LGUEST_H
 #define _ASM_LGUEST_H
-
-/* These are randomly chosen numbers which indicate we're an lguest at boot */
-#define LGUEST_MAGIC_EBP 0x4C687970
-#define LGUEST_MAGIC_EDI 0x652D4D65
-#define LGUEST_MAGIC_ESI 0xFFFFFFFF
 
 #ifndef __ASSEMBLY__
 #include <asm/irq.h>
include/linux/lguest_launcher.h +0 -8
diff -r 9a673a220ad6 include/linux/lguest_launcher.h
@@ -15,14 +15,6 @@ struct lguest_dma
  	u32 used_len;
 	u32 addr[LGUEST_MAX_DMA_SECTIONS];
 	u16 len[LGUEST_MAX_DMA_SECTIONS];
-};
-
-/* This is found at address 0. */
-struct lguest_boot_info
-{
-	u32 max_pfn;
-	u32 initrd_size;
-	char cmdline[256];
 };
 
 struct lguest_block_page
#43 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 8 lines · Eric W. Biederman

Reading this it occurs to me what I object to wasn't that clear.

I have no problem with the testing of %cs to see if we are not in ring0. That part while a little odd is fine, and we will certainly need a test to skip the protected instructions in head.S

What I object to in particular is having (struct lguest_info?) instead of using the standard format for kernel parameters pointed to in %esi.

Here's a rough patch to see what it looks like from an lguest POV. It's an improvement in many ways: I chose to hardcode the search for matching backend rather than use paravirt_probe-style magic.

It'd be nicer if there were a "struct boot_params" declaration, but we can't have everything.

Cheers,
Rusty.

Documentation/lguest/lguest.c +20 -9
diff -r 9a673a220ad6 Documentation/lguest/lguest.c
@@ -30,10 +30,12 @@
 #include <termios.h>
 #include <getopt.h>
 #include <zlib.h>
+typedef unsigned long long u64;
 typedef uint32_t u32;
 typedef uint16_t u16;
 typedef uint8_t u8;
 #include "../../include/linux/lguest_launcher.h"
+#include "../../include/asm-i386/e820.h"
 
 #define PAGE_PRESENT 0x7 	/* Present, RW, Execute */
 #define NET_PEERNUM 1
@@ -915,10 +917,10 @@ static void usage(void)
 
 int main(int argc, char *argv[])
 {
-	unsigned long mem, pgdir, start, page_offset;
+	unsigned long mem, pgdir, start, page_offset, initrd_size = 0;
 	int c, lguest_fd, waker_fd;
 	struct device_list device_list;
-	struct lguest_boot_info *boot = (void *)0;
+	void *boot = (void *)0;
 	const char *initrd_name = NULL;
 
 	device_list.max_infd = -1;
@@ -966,15 +968,24 @@ int main(int argc, char *argv[])
 	map_device_descriptors(&device_list, mem);
 
 	/* Map the initrd image if requested */
-	if (initrd_name)
-		boot->initrd_size = load_initrd(initrd_name, mem);
+	if (initrd_name) {
+		initrd_size = load_initrd(initrd_name, mem);
+		*(unsigned long *)(boot+0x218) = mem - initrd_size;
+		*(unsigned long *)(boot+0x21c) = initrd_size;
+	}
 
 	/* Set up the initial linar pagetables. */
-	pgdir = setup_pagetables(mem, boot->initrd_size, page_offset);
-
-	/* Give the guest the boot information it needs. */
-	concat(boot->cmdline, argv+optind+2);
-	boot->max_pfn = mem/getpagesize();
+	pgdir = setup_pagetables(mem, initrd_size, page_offset);
+
+	/* E820 memory map: ours is a simple, single region. */
+	*(char*)(boot+E820NR) = 1;
+	*((struct e820entry *)(boot+E820MAP)) 
+		= ((struct e820entry) { 0, mem, E820_RAM });
+	/* Command line pointer and command line (at 4096) */
+	*(void **)(boot + 0x228) = boot + 4096;
+	concat(boot + 4096, argv+optind+2);
+	/* Paravirt type: 1 == lguest */
+	*(int *)(boot + 0x23c) = 1;
 
 	lguest_fd = tell_kernel(pgdir, start, page_offset);
 	waker_fd = setup_waker(&device_list);
arch/i386/kernel/head.S +7 -24
diff -r 9a673a220ad6 arch/i386/kernel/head.S
@@ -504,34 +504,17 @@ ignore_int:
 #ifdef CONFIG_PARAVIRT
 startup_paravirt:
 	cld
+	movl %esi, %eax
+	addl $__PAGE_OFFSET, %eax
  	movl $(init_thread_union+THREAD_SIZE),%esp
 
-	/* We take pains to preserve all the regs. */
-	pushl	%edx
-	pushl	%ecx
-	pushl	%eax
-
-	pushl	$__start_paravirtprobe
-1:
-	movl	0(%esp), %eax
-	cmpl	$__stop_paravirtprobe, %eax
-	je	unhandled_paravirt
-	pushl	(%eax)
-	movl	8(%esp), %eax
-	call	*(%esp)
-	popl	%eax
-
-	movl	4(%esp), %eax
-	movl	8(%esp), %ecx
-	movl	12(%esp), %edx
-
-	addl	$4, (%esp)
-	jmp	1b
-
-unhandled_paravirt:
+#ifdef CONFIG_LGUEST_GUEST
+	cmpl	$1, 0x23c(%eax)
+	je	lguest_init
+#endif
 	/* Nothing wanted us: we're screwed. */
 	ud2
-#endif
+#endif /* CONFIG_PARAVIRT */
 
 /*
  * Real beginning of normal "text" segment
drivers/lguest/lguest.c +9 -14
diff -r 9a673a220ad6 drivers/lguest/lguest.c
@@ -53,7 +53,6 @@ struct lguest_data lguest_data = {
 	.blocked_interrupts = { 1 }, /* Block timer interrupts */
 };
 struct lguest_device_desc *lguest_devices;
-static __initdata const struct lguest_boot_info *boot = __va(0);
 
 static enum paravirt_lazy_mode lazy_mode;
 static void lguest_lazy_mode(enum paravirt_lazy_mode mode)
@@ -378,8 +377,7 @@ static __init char *lguest_memory_setup(
 	/* We do this here because lockcheck barfs if before start_kernel */
 	atomic_notifier_chain_register(&panic_notifier_list, &paniced);
 
-	e820.nr_map = 0;
-	add_memory_region(0, PFN_PHYS(boot->max_pfn), E820_RAM);
+	add_memory_region(E820_MAP->addr, E820_MAP->size, E820_MAP->type);
 	return "LGUEST";
 }
 
@@ -410,8 +408,14 @@ static unsigned lguest_patch(u8 type, u1
 	return insn_len;
 }
 
-__init void lguest_init(void)
-{
+__init void lguest_init(void *boot)
+{
+	/* Copy boot parameters first. */
+	memcpy(boot_params, boot, PARAM_SIZE);
+	memcpy(boot_command_line,
+	       __va(*(unsigned long *)(boot_params + NEW_CL_POINTER)),
+	       COMMAND_LINE_SIZE);
+
 	paravirt_ops.name = "lguest";
 	paravirt_ops.paravirt_enabled = 1;
 	paravirt_ops.kernel_rpl = 1;
@@ -460,7 +464,6 @@ __init void lguest_init(void)
 	paravirt_ops.wbinvd = lguest_wbinvd;
 
 	hcall(LHCALL_LGUEST_INIT, __pa(&lguest_data), 0, 0);
-	strncpy(boot_command_line, boot->cmdline, COMMAND_LINE_SIZE);
 
 	/* We use top of mem for initial pagetables. */
 	init_pg_tables_end = __pa(pg0);
@@ -487,14 +490,6 @@ __init void lguest_init(void)
 
 	add_preferred_console("hvc", 0, NULL);
 
-	if (boot->initrd_size) {
-		/* We stash this at top of memory. */
-		INITRD_START = boot->max_pfn*PAGE_SIZE - boot->initrd_size;
-		INITRD_SIZE = boot->initrd_size;
-		LOADER_TYPE = 0xFF;
-	}
-
 	pm_power_off = lguest_power_off;
 	start_kernel();
 }
-paravirt_probe(lguest_maybe_init);
drivers/lguest/lguest_asm.S +1 -20
diff -r 9a673a220ad6 drivers/lguest/lguest_asm.S
@@ -5,31 +5,12 @@
 /* FIXME: Once asm/processor-flags.h goes in, include that */
 #define X86_EFLAGS_IF 0x00000200
 
-/*
- * This is where we begin: head.S notes that paging is already enabled (which
- * doesn't happen in native boot) and calls the registered paravirt_probe
- * functions one at a time.  Ours is a simple assembler test for magic
- * registers.  If they're correct we jump to lguest_init.
- *
- * We put it in .init.text will be discarded after boot.
- */
-.section .init.text, "ax", @progbits
-ENTRY(lguest_maybe_init)
-	cmpl $LGUEST_MAGIC_EBP, %ebp
-	jne out
-	cmpl $LGUEST_MAGIC_EDI, %edi
-	jne out
-	cmpl $LGUEST_MAGIC_ESI, %esi
-	jne out
-	je lguest_init
-out:
-	ret
-
 /* The templates for inline patching. */
 #define LGUEST_PATCH(name, insns...)			\
 	lgstart_##name:	insns; lgend_##name:;		\
 	.globl lgstart_##name; .globl lgend_##name
 
+.section .init.text, "ax", @progbits
 LGUEST_PATCH(cli, movl $0, lguest_data+LGUEST_DATA_irq_enabled)
 LGUEST_PATCH(sti, movl $X86_EFLAGS_IF, lguest_data+LGUEST_DATA_irq_enabled)
 LGUEST_PATCH(popf, movl %eax, lguest_data+LGUEST_DATA_irq_enabled)
drivers/lguest/lguest_user.c +1 -3
diff -r 9a673a220ad6 drivers/lguest/lguest_user.c
@@ -7,13 +7,11 @@ static void setup_regs(struct lguest_reg
 static void setup_regs(struct lguest_regs *regs, unsigned long start)
 {
 	/* Write out stack in format lguest expects, so we can switch to it. */
-	regs->edi = LGUEST_MAGIC_EDI;
-	regs->ebp = LGUEST_MAGIC_EBP;
-	regs->esi = LGUEST_MAGIC_ESI;
 	regs->ds = regs->es = regs->ss = __KERNEL_DS|GUEST_PL;
 	regs->cs = __KERNEL_CS|GUEST_PL;
 	regs->eflags = 0x202; 	/* Interrupts enabled. */
 	regs->eip = start;
+	/* esi points to our boot information (physical address 0) */
 }
 
 /* + addr */
include/asm-i386/paravirt.h +0 -5
diff -r 9a673a220ad6 include/asm-i386/paravirt.h
@@ -221,11 +221,6 @@ struct paravirt_ops
 	void (*irq_enable_sysexit)(void);
 	void (*iret)(void);
 };
-
-/* Mark a paravirt probe function. */
-#define paravirt_probe(fn)						\
- static asmlinkage void (*__paravirtprobe_##fn)(void) __attribute_used__ \
-		__attribute__((__section__(".paravirtprobe"))) = fn
 
 extern struct paravirt_ops paravirt_ops;
 
include/linux/lguest.h +0 -5
diff -r 9a673a220ad6 include/linux/lguest.h
@@ -2,11 +2,6 @@
  * this is subject to wild and random change between versions. */
 #ifndef _ASM_LGUEST_H
 #define _ASM_LGUEST_H
-
-/* These are randomly chosen numbers which indicate we're an lguest at boot */
-#define LGUEST_MAGIC_EBP 0x4C687970
-#define LGUEST_MAGIC_EDI 0x652D4D65
-#define LGUEST_MAGIC_ESI 0xFFFFFFFF
 
 #ifndef __ASSEMBLY__
 #include <asm/irq.h>
include/linux/lguest_launcher.h +0 -8
diff -r 9a673a220ad6 include/linux/lguest_launcher.h
@@ -15,14 +15,6 @@ struct lguest_dma
  	u32 used_len;
 	u32 addr[LGUEST_MAX_DMA_SECTIONS];
 	u16 len[LGUEST_MAX_DMA_SECTIONS];
-};
-
-/* This is found at address 0. */
-struct lguest_boot_info
-{
-	u32 max_pfn;
-	u32 initrd_size;
-	char cmdline[256];
 };
 
 struct lguest_block_page
author
#73 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 9 lines · H. Peter Anvin
Quoted 5 lines · Eric W. Biederman

I'm tempted to just reload the segments in setup.S, but that might break loadlin support or one of the other bootloaders that starts the kernel in 32bit mode so we need to be careful.

We already load all the segments in setup.S. I'm retaining this in my rewrite.

It's still unclear to me why exactly you want to rewrite it? Are there any particular bugs in the current code you want to fix?

-Andi

#44 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Rusty Russell
Quoted 3 lines · Rusty Russell

It'd be nicer if there were a "struct boot_params" declaration, but we can't have everything.

It's in my patchset-under-development.

(Preview snapshot:
http://userweb.kernel.org/~hpa/setup-snapshot-2007.04.30.patch)

Documentation/lguest/lguest.c line 36

Quoted 11 lines

diff -r 9a673a220ad6 Documentation/lguest/lguest.c

Documentation/lguest/lguest.c +1 -0
@@ -30,10 +30,12 @@
 #include <termios.h>
 #include <getopt.h>
 #include <zlib.h>
+typedef unsigned long long u64;
 typedef uint32_t u32;
 typedef uint16_t u16;
 typedef uint8_t u8;

Why not uint64_t to go along with all the other defines?

-hpa

#52 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Rusty Russell
Quoted 7 lines · Rusty Russell
Quoted 6 lines · Eric W. Biederman

Reading this it occurs to me what I object to wasn't that clear.

I have no problem with the testing of %cs to see if we are not in ring0. That part while a little odd is fine, and we will certainly need a test to skip the protected instructions in head.S

Quoted 6 lines
Quoted 2 lines

What I object to in particular is having (struct lguest_info?) instead of using the standard format for kernel parameters pointed to in %esi.

Here's a rough patch to see what it looks like from an lguest POV. It's an improvement in many ways: I chose to hardcode the search for matching backend rather than use paravirt_probe-style magic.

Cool.

Quoted 2 lines

It'd be nicer if there were a "struct boot_params" declaration, but we can't have everything.

Well it will come. I have an old one in kexec-tools and HPA looks like he has one in his C rewrite.

I'm not going to worry about going farther until the patches in flight settle down a little bit, but this looks promising.

Eric

#45 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 6 lines · H. Peter Anvin
Quoted 3 lines · Rusty Russell

It'd be nicer if there were a "struct boot_params" declaration, but we can't have everything.

It's in my patchset-under-development.

Ah ha: excellent!

Quoted 6 lines
Quoted 4 lines

+typedef unsigned long long u64;
typedef uint32_t u32;
typedef uint16_t u16;
typedef uint8_t u8;

Why not uint64_t to go along with all the other defines?

Because then it's a PITA to printf(): x86-64 has uint64_t as "unsigned long". So the lguest64 guys will add all kinds of horrible casts. This has the same effect, but ironically is more portable.

Rusty.

#46 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 8 lines · H. Peter Anvin
Quoted 2 lines · Rusty Russell

It'd be nicer if there were a "struct boot_params" declaration, but we can't have everything.

It's in my patchset-under-development.

(Preview snapshot:
http://userweb.kernel.org/~hpa/setup-snapshot-2007.04.30.patch)

Just pushed out a git tree:

http://git.kernel.org/?p=linux/kernel/git/hpa/linux-2.6-newsetup.git;a=summary

-hpa

#47 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 5 lines · H. Peter Anvin
Quoted 4 lines · H. Peter Anvin
Quoted 2 lines · Rusty Russell

It'd be nicer if there were a "struct boot_params" declaration, but we can't have everything.

Quoted 8 lines
Quoted 4 lines

It's in my patchset-under-development.

(Preview snapshot:
http://userweb.kernel.org/~hpa/setup-snapshot-2007.04.30.patch)

Just pushed out a git tree:

http://git.kernel.org/?p=linux/kernel/git/hpa/linux-2.6-newsetup.git;a=summary

Any chance of splitting off a "struct boot_params" header (includable by non-kernel code) for inclusion immediately? The rest can wait until 2.6.23, but it'd be sweet to get this in place sooner.

BTW, wrt. a new "platform type" field, should it go something like this?

-0235/3 N/A pad2 Unused
+0235/1 2.07+ platform_type Runtime platform (see below)
+0236/2 N/A pad2 Unused
...
+ platform_type:
+ For kernels which can boot on multiple platforms. Currently
+ 0 == native (normal), 1 == lguest (paravirtualized).

Thanks,
Rusty.

#48 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 5 lines · H. Peter Anvin
Quoted 4 lines · H. Peter Anvin
Quoted 2 lines · Rusty Russell

It'd be nicer if there were a "struct boot_params" declaration, but we can't have everything.

Quoted 8 lines
Quoted 4 lines

It's in my patchset-under-development.

(Preview snapshot:
http://userweb.kernel.org/~hpa/setup-snapshot-2007.04.30.patch)

Just pushed out a git tree:

http://git.kernel.org/?p=linux/kernel/git/hpa/linux-2.6-newsetup.git;a=summary

Any chance of splitting off a "struct boot_params" header (includable by non-kernel code) for inclusion immediately? The rest can wait until 2.6.23, but it'd be sweet to get this in place sooner.

BTW, wrt. a new "platform type" field, should it go something like this?

-0235/3 N/A pad2 Unused
+0235/1 2.07+ platform_type Runtime platform (see below)
+0236/2 N/A pad2 Unused
...
+ platform_type:
+ For kernels which can boot on multiple platforms. Currently
+ 0 == native (normal), 1 == lguest (paravirtualized).

Thanks,
Rusty.

#49 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Review

Quoted 11 lines · Rusty Russell

BTW, wrt. a new "platform type" field, should it go something like this?

-0235/3 N/A pad2 Unused
+0235/1 2.07+ platform_type Runtime platform (see below)
+0236/2 N/A pad2 Unused
...

(quoted diff) +3 -0
+  platform_type:
+	For kernels which can boot on multiple platforms.  Currently
+	0 == native (normal), 1 == lguest (paravirtualized).

Well, yes, but we need to think about if there is more things that should be added. There *definitely* should be space for a platform data pointer, to start out with. I would also like to see a platform data field, as well as a bootloader extension field (we're going to have that problem soon enough.)

-hpa

#53 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 3 lines · Eric W. Biederman

I'm not going to worry about going farther until the patches in flight settle down a little bit, but this looks promising.

Is there any value in adding an "early-putchar" function pointer into the structure somehow? I could easily arrange for the domain builder to put a bit of code into the domain so that the early boot code can emit something.

J

#60 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 3 lines · Eric W. Biederman

I'm not going to worry about going farther until the patches in flight settle down a little bit, but this looks promising.

Is there any value in adding an "early-putchar" function pointer into the structure somehow? I could easily arrange for the domain builder to put a bit of code into the domain so that the early boot code can emit something.

J

#50 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 4 lines · H. Peter Anvin
Quoted 3 lines · Rusty Russell

BTW, wrt. a new "platform type" field, should it go something like this?

Quoted 14 lines

Review

Quoted 8 lines

-0235/3 N/A pad2 Unused
+0235/1 2.07+ platform_type Runtime platform (see below)
+0236/2 N/A pad2 Unused
...

(quoted diff) +3 -0
+  platform_type:
+	For kernels which can boot on multiple platforms.  Currently
+	0 == native (normal), 1 == lguest (paravirtualized).

Well, yes, but we need to think about if there is more things that should be added. There *definitely* should be space for a platform data pointer, to start out with. I would also like to see a platform data field, as well as a bootloader extension field (we're going to have that problem soon enough.)

Well in the paravirt case since we are starting virtually mapped if we don't start with vmlinux but bzImage we need to define what that virtual address space should contain, and where in the address space it is safe to put those page tables.

Of the requirements I have heard so far that is the trickiest one. Because it basically requires us to have a reasonable worst case estimate of how much memory we are going to use before we start using the bootmem allocator.

Eric

#51 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 4 lines · H. Peter Anvin
Quoted 3 lines · Rusty Russell

BTW, wrt. a new "platform type" field, should it go something like this?

Quoted 14 lines

Review

Quoted 8 lines

-0235/3 N/A pad2 Unused
+0235/1 2.07+ platform_type Runtime platform (see below)
+0236/2 N/A pad2 Unused
...

(quoted diff) +3 -0
+  platform_type:
+	For kernels which can boot on multiple platforms.  Currently
+	0 == native (normal), 1 == lguest (paravirtualized).

Well, yes, but we need to think about if there is more things that should be added. There *definitely* should be space for a platform data pointer, to start out with. I would also like to see a platform data field, as well as a bootloader extension field (we're going to have that problem soon enough.)

Well in the paravirt case since we are starting virtually mapped if we don't start with vmlinux but bzImage we need to define what that virtual address space should contain, and where in the address space it is safe to put those page tables.

Of the requirements I have heard so far that is the trickiest one. Because it basically requires us to have a reasonable worst case estimate of how much memory we are going to use before we start using the bootmem allocator.

Eric

#54 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 9 lines · Jeremy Fitzhardinge
Quoted 3 lines · Eric W. Biederman

I'm not going to worry about going farther until the patches in flight settle down a little bit, but this looks promising.

Is there any value in adding an "early-putchar" function pointer into the structure somehow? I could easily arrange for the domain builder to put a bit of code into the domain so that the early boot code can emit something.

I don't think so. Once we know what subarch it is we can do a specific hypervisor call if we need to for early printing. There are weird issues like physical vs virtual that would seem to make anything more generic very difficult to get right, because the code pointed at would need to be fully pic.

So as a trivial hypervisor call certainly, but I'm pretty doubtful about a function pointer.

Then we can do:

if (xen)
blah
else if (lguest)
blah2

Eric

#55 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 9 lines · Jeremy Fitzhardinge
Quoted 3 lines · Eric W. Biederman

I'm not going to worry about going farther until the patches in flight settle down a little bit, but this looks promising.

Is there any value in adding an "early-putchar" function pointer into the structure somehow? I could easily arrange for the domain builder to put a bit of code into the domain so that the early boot code can emit something.

I don't think so. Once we know what subarch it is we can do a specific hypervisor call if we need to for early printing. There are weird issues like physical vs virtual that would seem to make anything more generic very difficult to get right, because the code pointed at would need to be fully pic.

So as a trivial hypervisor call certainly, but I'm pretty doubtful about a function pointer.

Then we can do:

if (xen)
blah
else if (lguest)
blah2

Eric

#56 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 9 lines · Jeremy Fitzhardinge
Quoted 3 lines · Eric W. Biederman

I'm not going to worry about going farther until the patches in flight settle down a little bit, but this looks promising.

Is there any value in adding an "early-putchar" function pointer into the structure somehow? I could easily arrange for the domain builder to put a bit of code into the domain so that the early boot code can emit something.

Well there aren't that many instructions between startup_32 and lguest_init at the moment, but I guess if we end up going through bzImage decompression it makes more sense...

Rusty.

#57 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 9 lines · Jeremy Fitzhardinge
Quoted 3 lines · Eric W. Biederman

I'm not going to worry about going farther until the patches in flight settle down a little bit, but this looks promising.

Is there any value in adding an "early-putchar" function pointer into the structure somehow? I could easily arrange for the domain builder to put a bit of code into the domain so that the early boot code can emit something.

Well there aren't that many instructions between startup_32 and lguest_init at the moment, but I guess if we end up going through bzImage decompression it makes more sense...

Rusty.

#58 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 3 lines · Rusty Russell

Well there aren't that many instructions between startup_32 and lguest_init at the moment, but I guess if we end up going through bzImage decompression it makes more sense...

Yes, that's what I was thinking. If we boot compressed kernels in a novel environment, there's going to be plenty of early debugging going on. Fortunately for me, I can just start it up under gdb, so it isn't all that arduous.

J

#59 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Rusty Russell
Quoted 3 lines · Rusty Russell

Well there aren't that many instructions between startup_32 and lguest_init at the moment, but I guess if we end up going through bzImage decompression it makes more sense...

Yes, that's what I was thinking. If we boot compressed kernels in a novel environment, there's going to be plenty of early debugging going on. Fortunately for me, I can just start it up under gdb, so it isn't all that arduous.

J

#75 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 8 lines · Jeremy Fitzhardinge
Quoted 2 lines · Eric W. Biederman

I have several ideas on how we can make this work but first I have to ask what is it that you are trying to accomplish?

The requirements are:

1. the domain builder needs to get various information about the guest kernel by inspecting its ELF notes

Doesn't need to be ELF notes. The current (3.0.5+) domain builder has pluggable binary parsers. Right now there are two: ELF (obviously ...) and binary (with a multiboot-like header). Filling the informations such as virt_base is a function of the parser, so when adding one more parser to the domain builder for bzImage kernels the parser could do something completely different to gather the needed information ...

Quoted 4 lines

That works OK for a kernel which is compiled to run under Xen and can't run in any other environment, but now that we can generate a single kernel which can run in any number of different environments, its unfortunate that we still need multiple variants of the kernel image.

Yep, although already much better than completely different kernels. Most space of a typical distro kernel is modules which are shared even with different kernel binaries.

Quoted 3 lines

So, I have no problem in also building a boot protocol info structure, and passing that in %esi, so long as I can store a pointer to the Xen-specific info as well.

Yep, should work fine.

Quoted 3 lines

I think I'd prefer to have the domain builder decompress/relocate the kernel from the bzImage and start it directly, rather than have it decompress/relocate itself,

I'd expect that work better too.

Quoted 2 lines

It depends
on how well it can deal with having paging enabled and being in ring 1.

Xen direct paging mode requiring (leaf) page tables being mapped read-only makes page table manipulation a bit difficult. Xen has to care whenever the memory it maps is a page table. Native hasn't.

Also switching to a completely different set of page tables isn't easy under Xen. My xen guest kexec patches have to perform some intresting tricks because of that ...

Quoted 2 lines

Looks like it might just be a matter of starting up with "enough" memory mapped.

Doesn't solve the problem of having to switch from identity mapping to the 0xc0000000 one ...

cheers,
Gerd

#76 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 8 lines · Jeremy Fitzhardinge
Quoted 2 lines · Eric W. Biederman

I have several ideas on how we can make this work but first I have to ask what is it that you are trying to accomplish?

The requirements are:

1. the domain builder needs to get various information about the guest kernel by inspecting its ELF notes

Doesn't need to be ELF notes. The current (3.0.5+) domain builder has pluggable binary parsers. Right now there are two: ELF (obviously ...) and binary (with a multiboot-like header). Filling the informations such as virt_base is a function of the parser, so when adding one more parser to the domain builder for bzImage kernels the parser could do something completely different to gather the needed information ...

Quoted 4 lines

That works OK for a kernel which is compiled to run under Xen and can't run in any other environment, but now that we can generate a single kernel which can run in any number of different environments, its unfortunate that we still need multiple variants of the kernel image.

Yep, although already much better than completely different kernels. Most space of a typical distro kernel is modules which are shared even with different kernel binaries.

Quoted 3 lines

So, I have no problem in also building a boot protocol info structure, and passing that in %esi, so long as I can store a pointer to the Xen-specific info as well.

Yep, should work fine.

Quoted 3 lines

I think I'd prefer to have the domain builder decompress/relocate the kernel from the bzImage and start it directly, rather than have it decompress/relocate itself,

I'd expect that work better too.

Quoted 2 lines

It depends
on how well it can deal with having paging enabled and being in ring 1.

Xen direct paging mode requiring (leaf) page tables being mapped read-only makes page table manipulation a bit difficult. Xen has to care whenever the memory it maps is a page table. Native hasn't.

Also switching to a completely different set of page tables isn't easy under Xen. My xen guest kexec patches have to perform some intresting tricks because of that ...

Quoted 2 lines

Looks like it might just be a matter of starting up with "enough" memory mapped.

Doesn't solve the problem of having to switch from identity mapping to the 0xc0000000 one ...

cheers,
Gerd

#77 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 7 lines · Gerd Hoffmann

Doesn't need to be ELF notes. The current (3.0.5+) domain builder has pluggable binary parsers. Right now there are two: ELF (obviously ...) and binary (with a multiboot-like header). Filling the informations such as virt_base is a function of the parser, so when adding one more parser to the domain builder for bzImage kernels the parser could do something completely different to gather the needed information ...

True. But the plan is already to make bzImage an ELF file, so notes would seem to be the best option. At worst, it could be ELF notes wrapped in some other container, but that's not pretty.

Quoted 8 lines
Quoted 4 lines

That works OK for a kernel which is compiled to run under Xen and can't run in any other environment, but now that we can generate a single kernel which can run in any number of different environments, its unfortunate that we still need multiple variants of the kernel image.

Yep, although already much better than completely different kernels. Most space of a typical distro kernel is modules which are shared even with different kernel binaries.

Yep.

Quoted 15 lines
Quoted 3 lines

So, I have no problem in also building a boot protocol info structure, and passing that in %esi, so long as I can store a pointer to the Xen-specific info as well.

Yep, should work fine.

Quoted 3 lines

I think I'd prefer to have the domain builder decompress/relocate the kernel from the bzImage and start it directly, rather than have it decompress/relocate itself,

I'd expect that work better too.

Quoted 2 lines

It depends
on how well it can deal with having paging enabled and being in ring 1.

Quoted 7 lines

Xen direct paging mode requiring (leaf) page tables being mapped read-only makes page table manipulation a bit difficult. Xen has to care whenever the memory it maps is a page table. Native hasn't.

Also switching to a completely different set of page tables isn't easy under Xen. My xen guest kexec patches have to perform some intresting tricks because of that ...

Yeah, that's tricky. I ended up copying the Xen pagetables's pmd into the kernel's so that they could share ptes. Making a completely new pagetable means you need to update the RO state on both old and new.

Quoted 5 lines
Quoted 2 lines

Looks like it might just be a matter of starting up with "enough" memory mapped.

Doesn't solve the problem of having to switch from identity mapping to the 0xc0000000 one ...

Hm. That's right. Xen will boot a vmlinux with its pagetable pre-constructed to map it at its virtual address. Going through bzImage would mean it would be identity mapped, and someone early would need to construct the virtual mapping.

But if the path is:

1. enter bzImage in 32-bit mode
2. decompress kernel
3. jump to startup_32
4. detect paravirt and choose appropriate backend
5. run Xen startup code

then the Xen startup code can construct the virtual mapping before going on with the rest of the kernel boot - steps 1-4 can be run with identity mapping.

J

#78 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Gerd Hoffmann
Quoted 7 lines · Gerd Hoffmann

Doesn't need to be ELF notes. The current (3.0.5+) domain builder has pluggable binary parsers. Right now there are two: ELF (obviously ...) and binary (with a multiboot-like header). Filling the informations such as virt_base is a function of the parser, so when adding one more parser to the domain builder for bzImage kernels the parser could do something completely different to gather the needed information ...

True. But the plan is already to make bzImage an ELF file, so notes would seem to be the best option. At worst, it could be ELF notes wrapped in some other container, but that's not pretty.

Quoted 8 lines
Quoted 4 lines

That works OK for a kernel which is compiled to run under Xen and can't run in any other environment, but now that we can generate a single kernel which can run in any number of different environments, its unfortunate that we still need multiple variants of the kernel image.

Yep, although already much better than completely different kernels. Most space of a typical distro kernel is modules which are shared even with different kernel binaries.

Yep.

Quoted 15 lines
Quoted 3 lines

So, I have no problem in also building a boot protocol info structure, and passing that in %esi, so long as I can store a pointer to the Xen-specific info as well.

Yep, should work fine.

Quoted 3 lines

I think I'd prefer to have the domain builder decompress/relocate the kernel from the bzImage and start it directly, rather than have it decompress/relocate itself,

I'd expect that work better too.

Quoted 2 lines

It depends
on how well it can deal with having paging enabled and being in ring 1.

Quoted 7 lines

Xen direct paging mode requiring (leaf) page tables being mapped read-only makes page table manipulation a bit difficult. Xen has to care whenever the memory it maps is a page table. Native hasn't.

Also switching to a completely different set of page tables isn't easy under Xen. My xen guest kexec patches have to perform some intresting tricks because of that ...

Yeah, that's tricky. I ended up copying the Xen pagetables's pmd into the kernel's so that they could share ptes. Making a completely new pagetable means you need to update the RO state on both old and new.

Quoted 5 lines
Quoted 2 lines

Looks like it might just be a matter of starting up with "enough" memory mapped.

Doesn't solve the problem of having to switch from identity mapping to the 0xc0000000 one ...

Hm. That's right. Xen will boot a vmlinux with its pagetable pre-constructed to map it at its virtual address. Going through bzImage would mean it would be identity mapped, and someone early would need to construct the virtual mapping.

But if the path is:

1. enter bzImage in 32-bit mode
2. decompress kernel
3. jump to startup_32
4. detect paravirt and choose appropriate backend
5. run Xen startup code

then the Xen startup code can construct the virtual mapping before going on with the rest of the kernel boot - steps 1-4 can be run with identity mapping.

J

#79 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 5 lines · Jeremy Fitzhardinge

True. But the plan is already to make bzImage an ELF file, so notes would seem to be the best option. At worst, it could be ELF notes wrapped in some other container, but that's not pretty.

It's not going to happen. Too many boot loaders make assumptions about ELF files which aren't really compatible; the entry conditions for an ELF from a boot loader are pretty ill-defined, so I think this is a bad idea.

At the very least, it shouldn't present the ELF magic number IMNSHO.

-hpa

#80 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 5 lines · Jeremy Fitzhardinge

True. But the plan is already to make bzImage an ELF file, so notes would seem to be the best option. At worst, it could be ELF notes wrapped in some other container, but that's not pretty.

It's not going to happen. Too many boot loaders make assumptions about ELF files which aren't really compatible; the entry conditions for an ELF from a boot loader are pretty ill-defined, so I think this is a bad idea.

At the very least, it shouldn't present the ELF magic number IMNSHO.

-hpa

#81 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 8 lines · H. Peter Anvin
Quoted 5 lines · Jeremy Fitzhardinge

True. But the plan is already to make bzImage an ELF file, so notes would seem to be the best option. At worst, it could be ELF notes wrapped in some other container, but that's not pretty.

Quoted 7 lines

It's not going to happen. Too many boot loaders make assumptions about ELF files which aren't really compatible; the entry conditions for an ELF from a boot loader are pretty ill-defined, so I think this is a bad idea.

At the very least, it shouldn't present the ELF magic number IMNSHO.

Hm, that's unfortunate. How about an ELF file wrapped in some other container, so that we can easily extract a properly formed ELF file?

J

#82 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 8 lines · H. Peter Anvin
Quoted 5 lines · Jeremy Fitzhardinge

True. But the plan is already to make bzImage an ELF file, so notes would seem to be the best option. At worst, it could be ELF notes wrapped in some other container, but that's not pretty.

Quoted 7 lines

It's not going to happen. Too many boot loaders make assumptions about ELF files which aren't really compatible; the entry conditions for an ELF from a boot loader are pretty ill-defined, so I think this is a bad idea.

At the very least, it shouldn't present the ELF magic number IMNSHO.

Hm, that's unfortunate. How about an ELF file wrapped in some other container, so that we can easily extract a properly formed ELF file?

J

#83 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 4 lines · Jeremy Fitzhardinge

Hm, that's unfortunate. How about an ELF file wrapped in some other container, so that we can easily extract a properly formed ELF file?

Effectively the same thing as changing the magic number. Note that the format for bzImage is pretty rigid, and it would be *highly* undesirable to muck that up.

-hpa

#84 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 4 lines · Jeremy Fitzhardinge

Hm, that's unfortunate. How about an ELF file wrapped in some other container, so that we can easily extract a properly formed ELF file?

Effectively the same thing as changing the magic number. Note that the format for bzImage is pretty rigid, and it would be *highly* undesirable to muck that up.

-hpa

#192 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 7 lines · H. Peter Anvin
Quoted 5 lines · Jeremy Fitzhardinge

True. But the plan is already to make bzImage an ELF file, so notes would seem to be the best option. At worst, it could be ELF notes wrapped in some other container, but that's not pretty.

Quoted 6 lines

It's not going to happen. Too many boot loaders make assumptions about ELF files which aren't really compatible; the entry conditions for an ELF from a boot loader are pretty ill-defined, so I think this is a bad idea.

At the very least, it shouldn't present the ELF magic number IMNSHO.

I agree that there are some issues.

However we need the information that is contained in ELF headers or a semantic equivalent so we might as well play with the possibility.

There are two practical issues for ELF and bootloaders.
virtual vs. physical addresses. In a bzImage header all
we will present will be physical addresses so that isn't an issue.

The other issue is what is the format of the arguments that the executable expects. There seems to be 0 consensus on this so bootloaders simply can't agree, and any bootloader that is prepared to deal with kernels from different locations is going to have to cope.

So I figure we keep our current calling conventions and have a note saying that we are linux so the format can be auto-detected.

There are of course plenty of bootloaders that load whatever happens to be their OS kernel however they managed to get ld to spit it out, and there are some really weird things going on there. But that doesn't matter because those bootloaders can make no pretense at being general purpose.

There is a lot of future flexibility that comes from this in addition to making x86 closer to the other architectures.

I do agree we need to tread carefully, but I have yet to hear about any show stopper bugs, and it works well enough at least one major distro has shipped a linux kernel bzImage with an ELF header.

So we won't do this casually and if it there are real problems we will remove the ELF magic number.

Eric

#193 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 7 lines · H. Peter Anvin
Quoted 5 lines · Jeremy Fitzhardinge

True. But the plan is already to make bzImage an ELF file, so notes would seem to be the best option. At worst, it could be ELF notes wrapped in some other container, but that's not pretty.

Quoted 6 lines

It's not going to happen. Too many boot loaders make assumptions about ELF files which aren't really compatible; the entry conditions for an ELF from a boot loader are pretty ill-defined, so I think this is a bad idea.

At the very least, it shouldn't present the ELF magic number IMNSHO.

I agree that there are some issues.

However we need the information that is contained in ELF headers or a semantic equivalent so we might as well play with the possibility.

There are two practical issues for ELF and bootloaders.
virtual vs. physical addresses. In a bzImage header all
we will present will be physical addresses so that isn't an issue.

The other issue is what is the format of the arguments that the executable expects. There seems to be 0 consensus on this so bootloaders simply can't agree, and any bootloader that is prepared to deal with kernels from different locations is going to have to cope.

So I figure we keep our current calling conventions and have a note saying that we are linux so the format can be auto-detected.

There are of course plenty of bootloaders that load whatever happens to be their OS kernel however they managed to get ld to spit it out, and there are some really weird things going on there. But that doesn't matter because those bootloaders can make no pretense at being general purpose.

There is a lot of future flexibility that comes from this in addition to making x86 closer to the other architectures.

I do agree we need to tread carefully, but I have yet to hear about any show stopper bugs, and it works well enough at least one major distro has shipped a linux kernel bzImage with an ELF header.

So we won't do this casually and if it there are real problems we will remove the ELF magic number.

Eric

#194 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 4 lines · Eric W. Biederman

So we won't do this casually and if it there are real problems we will remove the ELF magic number.

I think we can use ELF-compatible format just fine, but it would make more sense to use a non-ELF magic number from the start, instead of signalling it with a note. Since bootloaders need to be aware, anyway, they can just detect this magic and treat is as an Linux calling convention ELF image, or they can not detect it, and treat it as a bzImage. As a side benefit, we:

a) can use a magic number that contains a jump instruction (to keep the non-bootsector happy);
b) get a proper Linux kernel magic number.

-hpa

#195 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 4 lines · Eric W. Biederman

So we won't do this casually and if it there are real problems we will remove the ELF magic number.

I think we can use ELF-compatible format just fine, but it would make more sense to use a non-ELF magic number from the start, instead of signalling it with a note. Since bootloaders need to be aware, anyway, they can just detect this magic and treat is as an Linux calling convention ELF image, or they can not detect it, and treat it as a bzImage. As a side benefit, we:

a) can use a magic number that contains a jump instruction (to keep the non-bootsector happy);
b) get a proper Linux kernel magic number.

-hpa

#196 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 13 lines · H. Peter Anvin
Quoted 4 lines · Eric W. Biederman

So we won't do this casually and if it there are real problems we will remove the ELF magic number.

I think we can use ELF-compatible format just fine, but it would make more sense to use a non-ELF magic number from the start, instead of signalling it with a note. Since bootloaders need to be aware, anyway, they can just detect this magic and treat is as an Linux calling convention ELF image, or they can not detect it, and treat it as a bzImage. As a side benefit, we:

Quoted 3 lines

a) can use a magic number that contains a jump instruction (to keep the non-bootsector happy);
b) get a proper Linux kernel magic number.

To the best of my knowledge I have already resolved both of those concerns, in my current code.

Eric

#197 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 13 lines · H. Peter Anvin
Quoted 4 lines · Eric W. Biederman

So we won't do this casually and if it there are real problems we will remove the ELF magic number.

I think we can use ELF-compatible format just fine, but it would make more sense to use a non-ELF magic number from the start, instead of signalling it with a note. Since bootloaders need to be aware, anyway, they can just detect this magic and treat is as an Linux calling convention ELF image, or they can not detect it, and treat it as a bzImage. As a side benefit, we:

Quoted 3 lines

a) can use a magic number that contains a jump instruction (to keep the non-bootsector happy);
b) get a proper Linux kernel magic number.

To the best of my knowledge I have already resolved both of those concerns, in my current code.

Eric

#85 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 10 lines · H. Peter Anvin
Quoted 4 lines · Jeremy Fitzhardinge

Hm, that's unfortunate. How about an ELF file wrapped in some other container, so that we can easily extract a properly formed ELF file?

Effectively the same thing as changing the magic number. Note that the format for bzImage is pretty rigid, and it would be *highly* undesirable to muck that up.

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

If we make 5 actually an ELF file, containing properly formed Ehdr, Phdrs (for all the mappings required), and the actual kernel decompressor, relocator and compressed kernel data, then it would be easy for the Xen domain builder to find that and use it as a basis for loading. I think it would just require the bzImage boot param block to contain an offset of the start of the ELF file. The contents of the ELF file would be in a form where the normal boot code could just jump over the ELF headers, directly into the segment data itself.

ie:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code (jumps directly into 5.3)
5. 32-bit self-decompressing kernel:
1. Ehdr
2. Phdrs for all necessary mappings
3. decompressor/relocator .text
4. compressed kernel data

Does that sound reasonable?

J

#86 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 10 lines · H. Peter Anvin
Quoted 4 lines · Jeremy Fitzhardinge

Hm, that's unfortunate. How about an ELF file wrapped in some other container, so that we can easily extract a properly formed ELF file?

Effectively the same thing as changing the magic number. Note that the format for bzImage is pretty rigid, and it would be *highly* undesirable to muck that up.

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

If we make 5 actually an ELF file, containing properly formed Ehdr, Phdrs (for all the mappings required), and the actual kernel decompressor, relocator and compressed kernel data, then it would be easy for the Xen domain builder to find that and use it as a basis for loading. I think it would just require the bzImage boot param block to contain an offset of the start of the ELF file. The contents of the ELF file would be in a form where the normal boot code could just jump over the ELF headers, directly into the segment data itself.

ie:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code (jumps directly into 5.3)
5. 32-bit self-decompressing kernel:
1. Ehdr
2. Phdrs for all necessary mappings
3. decompressor/relocator .text
4. compressed kernel data

Does that sound reasonable?

J

#87 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 30 lines · Jeremy Fitzhardinge

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

If we make 5 actually an ELF file, containing properly formed Ehdr, Phdrs (for all the mappings required), and the actual kernel decompressor, relocator and compressed kernel data, then it would be easy for the Xen domain builder to find that and use it as a basis for loading. I think it would just require the bzImage boot param block to contain an offset of the start of the ELF file. The contents of the ELF file would be in a form where the normal boot code could just jump over the ELF headers, directly into the segment data itself.

ie:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code (jumps directly into 5.3)
5. 32-bit self-decompressing kernel:
1. Ehdr
2. Phdrs for all necessary mappings
3. decompressor/relocator .text
4. compressed kernel data

Quoted 2 lines

Does that sound reasonable?

I don't know if that would break any programs that are currently bypassing the setup. The existing setup protocol definitely allows invoking an entry point which isn't 0x100000 (rather, the 32-bit entrypoint is defined by code32_start); I'm not sure how Eric's relocatable kernel patches (2.05 protocol) affect that, mostly because I haven't seen any boot loaders which actually use it so I can't comment on what their code looks like.

-hpa

#88 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 30 lines · Jeremy Fitzhardinge

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

If we make 5 actually an ELF file, containing properly formed Ehdr, Phdrs (for all the mappings required), and the actual kernel decompressor, relocator and compressed kernel data, then it would be easy for the Xen domain builder to find that and use it as a basis for loading. I think it would just require the bzImage boot param block to contain an offset of the start of the ELF file. The contents of the ELF file would be in a form where the normal boot code could just jump over the ELF headers, directly into the segment data itself.

ie:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code (jumps directly into 5.3)
5. 32-bit self-decompressing kernel:
1. Ehdr
2. Phdrs for all necessary mappings
3. decompressor/relocator .text
4. compressed kernel data

Quoted 2 lines

Does that sound reasonable?

I don't know if that would break any programs that are currently bypassing the setup. The existing setup protocol definitely allows invoking an entry point which isn't 0x100000 (rather, the 32-bit entrypoint is defined by code32_start); I'm not sure how Eric's relocatable kernel patches (2.05 protocol) affect that, mostly because I haven't seen any boot loaders which actually use it so I can't comment on what their code looks like.

-hpa

#89 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 7 lines · H. Peter Anvin

I don't know if that would break any programs that are currently bypassing the setup. The existing setup protocol definitely allows invoking an entry point which isn't 0x100000 (rather, the 32-bit entrypoint is defined by code32_start); I'm not sure how Eric's relocatable kernel patches (2.05 protocol) affect that, mostly because I haven't seen any boot loaders which actually use it so I can't comment on what their code looks like.

Yes, I'd expect that code32_start would point into the ELF text
segment. You could align things so that the entrypoint is still
actually 0x100000, or bump it up a bit to fit the ELF headers. I have to admit I don't quite understand how all that fits together at the moment.

J

#90 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 7 lines · H. Peter Anvin

I don't know if that would break any programs that are currently bypassing the setup. The existing setup protocol definitely allows invoking an entry point which isn't 0x100000 (rather, the 32-bit entrypoint is defined by code32_start); I'm not sure how Eric's relocatable kernel patches (2.05 protocol) affect that, mostly because I haven't seen any boot loaders which actually use it so I can't comment on what their code looks like.

Yes, I'd expect that code32_start would point into the ELF text
segment. You could align things so that the entrypoint is still
actually 0x100000, or bump it up a bit to fit the ELF headers. I have to admit I don't quite understand how all that fits together at the moment.

J

#190 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 9 lines · H. Peter Anvin
Quoted 4 lines · Jeremy Fitzhardinge

Hm, that's unfortunate. How about an ELF file wrapped in some other container, so that we can easily extract a properly formed ELF file?

Effectively the same thing as changing the magic number. Note that the format for bzImage is pretty rigid, and it would be *highly* undesirable to muck that up.

To add some code to the debate, here's how lguest loads a bzImage (from my draft documentation). Almost anything would be an improvement:

/* A bzImage, unlike an ELF file, is not meant to be loaded. You're
* supposed to jump into it and it will unpack itself. We can't do that
* because the Guest can't run the unpacking code, and adding features to
* lguest kills puppies, so we don't want to.
*
* The bzImage is formed by putting the decompressing code in front of the
* compressed kernel code. So we can simple scan through it looking for the
* first "gzip" header, and start decompressing from there. */
static unsigned long load_bzimage(int fd, unsigned long *page_offset)

{
	unsigned char c;
	int state = 0;

	/* GZIP header is 0x1F 0x8B <method> <flags>... <compressed-by>. */
	while (read(fd, &c, 1) == 1) {
		switch (state) {
		case 0:
			if (c == 0x1F)
				state++;
			break;
		case 1:
			if (c == 0x8B)
				state++;
			else
				state = 0;
			break;
		case 2 ... 8:
			state++;
			break;
		case 9:
			/* Seek back to the start of the gzip header. */
			lseek(fd, -10, SEEK_CUR);
			/* One final check: "compressed under UNIX". */
			if (c != 0x03)
				state = -1;
			else
				return unpack_bzimage(fd, page_offset);
		}
	}
	errx(1, "Could not find kernel in bzImage");
}

/* Unfortunately the entire ELF image isn't compressed: the segments
* which need loading are extracted and compressed raw. This denies us the
* information we need to make a fully-general loader. */
static unsigned long unpack_bzimage(int fd, unsigned long *page_offset)

{
	gzFile f;
	int ret, len = 0;
	/* A bzImage always gets loaded at physical address 1M.  This is
	 * actually configurable as CONFIG_PHYSICAL_START, but as the comment
	 * there says, "Don't change this unless you know what you are doing".
	 * Indeed. */
	void *img = (void *)0x100000;

	/* gzdopen takes our file descriptor (carefully placed at the start of
	 * the GZIP header we found) and returns a gzFile. */
	f = gzdopen(fd, "rb");
	/* Unfortunately, if we made a mistake and it wasn't really a gzip
	 * header, it will still read the file, but directly without
	 * decompressing it.  For us, that's a misfeature. */
	if (gzdirect(f))
		errx(1, "did not find correct gzip header");
	/* We read it into memory in 64k chunks until we hit the end. */
	while ((ret = gzread(f, img + len, 65536)) > 0)
		len += ret;
	if (ret < 0)
		err(1, "reading image from bzImage");

	verbose("Unpacked size %i addr %p\n", len, img);

	/* Without the ELF header, we can't tell virtual-physical gap.  This is
	 * CONFIG_PAGE_OFFSET, and people do actually change it.  Fortunately,
	 * I have a clever way of figuring it out from the code itself.  */
	*page_offset = intuit_page_offset(img, len);

	/* Entry is physical address: convert to virtual */
	return (unsigned long)img + *page_offset;
}

/* Prepare to be SHOCKED and AMAZED. And possibly a trifle nauseated.
*
* We know that CONFIG_PAGE_OFFSET sets what virtual address the kernel expects
* to be. We don't know what that option was, but we can figure it out
* approximately by looking at the addresses in the code. I chose the common
* case of reading a memory location into the %eax register:
*
* movl <some-address>, %eax
*
* This gets encoded as five bytes: "0xA1 <4-byte-address>". For example,
* "0xA1 0x18 0x60 0x47 0xC0" reads the address 0xC0476018 into %eax. *
* In this example can guess that the kernel was compiled with
* CONFIG_PAGE_OFFSET set to 0xC0000000 (it's always a round number). If the
* kernel were larger than 16MB, we might see 0xC1 addresses show up, but our
* kernel isn't that bloated yet.
*
* Unfortunately, x86 has variable-length instructions, so finding this
* particular instruction properly involves writing a disassembler. Instead,
* we rely on statistics. We look for "0xA1" and tally the different bytes
* which occur 4 bytes later (the "0xC0" in our example above). When one of
* those bytes appears three times, we can be reasonably confident that it
* forms the start of CONFIG_PAGE_OFFSET.
*
* This is amazingly reliable. */
static unsigned long intuit_page_offset(unsigned char *img, unsigned long len)

{
	unsigned int i, possibilities[256] = { 0 };

	for (i = 0; i + 4 < len; i++) {
		/* mov 0xXXXXXXXX,%eax */
		if (img[i] == 0xA1 && ++possibilities[img[i+4]] > 3)
			return (unsigned long)img[i+4] << 24;
	}
	errx(1, "could not determine page offset");
}
#191 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 9 lines · H. Peter Anvin
Quoted 4 lines · Jeremy Fitzhardinge

Hm, that's unfortunate. How about an ELF file wrapped in some other container, so that we can easily extract a properly formed ELF file?

Effectively the same thing as changing the magic number. Note that the format for bzImage is pretty rigid, and it would be *highly* undesirable to muck that up.

To add some code to the debate, here's how lguest loads a bzImage (from my draft documentation). Almost anything would be an improvement:

/* A bzImage, unlike an ELF file, is not meant to be loaded. You're
* supposed to jump into it and it will unpack itself. We can't do that
* because the Guest can't run the unpacking code, and adding features to
* lguest kills puppies, so we don't want to.
*
* The bzImage is formed by putting the decompressing code in front of the
* compressed kernel code. So we can simple scan through it looking for the
* first "gzip" header, and start decompressing from there. */
static unsigned long load_bzimage(int fd, unsigned long *page_offset)

{
	unsigned char c;
	int state = 0;

	/* GZIP header is 0x1F 0x8B <method> <flags>... <compressed-by>. */
	while (read(fd, &c, 1) == 1) {
		switch (state) {
		case 0:
			if (c == 0x1F)
				state++;
			break;
		case 1:
			if (c == 0x8B)
				state++;
			else
				state = 0;
			break;
		case 2 ... 8:
			state++;
			break;
		case 9:
			/* Seek back to the start of the gzip header. */
			lseek(fd, -10, SEEK_CUR);
			/* One final check: "compressed under UNIX". */
			if (c != 0x03)
				state = -1;
			else
				return unpack_bzimage(fd, page_offset);
		}
	}
	errx(1, "Could not find kernel in bzImage");
}

/* Unfortunately the entire ELF image isn't compressed: the segments
* which need loading are extracted and compressed raw. This denies us the
* information we need to make a fully-general loader. */
static unsigned long unpack_bzimage(int fd, unsigned long *page_offset)

{
	gzFile f;
	int ret, len = 0;
	/* A bzImage always gets loaded at physical address 1M.  This is
	 * actually configurable as CONFIG_PHYSICAL_START, but as the comment
	 * there says, "Don't change this unless you know what you are doing".
	 * Indeed. */
	void *img = (void *)0x100000;

	/* gzdopen takes our file descriptor (carefully placed at the start of
	 * the GZIP header we found) and returns a gzFile. */
	f = gzdopen(fd, "rb");
	/* Unfortunately, if we made a mistake and it wasn't really a gzip
	 * header, it will still read the file, but directly without
	 * decompressing it.  For us, that's a misfeature. */
	if (gzdirect(f))
		errx(1, "did not find correct gzip header");
	/* We read it into memory in 64k chunks until we hit the end. */
	while ((ret = gzread(f, img + len, 65536)) > 0)
		len += ret;
	if (ret < 0)
		err(1, "reading image from bzImage");

	verbose("Unpacked size %i addr %p\n", len, img);

	/* Without the ELF header, we can't tell virtual-physical gap.  This is
	 * CONFIG_PAGE_OFFSET, and people do actually change it.  Fortunately,
	 * I have a clever way of figuring it out from the code itself.  */
	*page_offset = intuit_page_offset(img, len);

	/* Entry is physical address: convert to virtual */
	return (unsigned long)img + *page_offset;
}

/* Prepare to be SHOCKED and AMAZED. And possibly a trifle nauseated.
*
* We know that CONFIG_PAGE_OFFSET sets what virtual address the kernel expects
* to be. We don't know what that option was, but we can figure it out
* approximately by looking at the addresses in the code. I chose the common
* case of reading a memory location into the %eax register:
*
* movl <some-address>, %eax
*
* This gets encoded as five bytes: "0xA1 <4-byte-address>". For example,
* "0xA1 0x18 0x60 0x47 0xC0" reads the address 0xC0476018 into %eax. *
* In this example can guess that the kernel was compiled with
* CONFIG_PAGE_OFFSET set to 0xC0000000 (it's always a round number). If the
* kernel were larger than 16MB, we might see 0xC1 addresses show up, but our
* kernel isn't that bloated yet.
*
* Unfortunately, x86 has variable-length instructions, so finding this
* particular instruction properly involves writing a disassembler. Instead,
* we rely on statistics. We look for "0xA1" and tally the different bytes
* which occur 4 bytes later (the "0xC0" in our example above). When one of
* those bytes appears three times, we can be reasonably confident that it
* forms the start of CONFIG_PAGE_OFFSET.
*
* This is amazingly reliable. */
static unsigned long intuit_page_offset(unsigned char *img, unsigned long len)

{
	unsigned int i, possibilities[256] = { 0 };

	for (i = 0; i + 4 < len; i++) {
		/* mov 0xXXXXXXXX,%eax */
		if (img[i] == 0xA1 && ++possibilities[img[i+4]] > 3)
			return (unsigned long)img[i+4] << 24;
	}
	errx(1, "could not determine page offset");
}
#91 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 31 lines · H. Peter Anvin
Quoted 30 lines · Jeremy Fitzhardinge

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

If we make 5 actually an ELF file, containing properly formed Ehdr, Phdrs (for all the mappings required), and the actual kernel decompressor, relocator and compressed kernel data, then it would be easy for the Xen domain builder to find that and use it as a basis for loading. I think it would just require the bzImage boot param block to contain an offset of the start of the ELF file. The contents of the ELF file would be in a form where the normal boot code could just jump over the ELF headers, directly into the segment data itself.

ie:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code (jumps directly into 5.3)
5. 32-bit self-decompressing kernel:
1. Ehdr
2. Phdrs for all necessary mappings
3. decompressor/relocator .text
4. compressed kernel data

Quoted 5 lines
Quoted 2 lines

Does that sound reasonable?

I don't know if that would break any programs that are currently bypassing the setup.

I think kexec bzImage loader will break. It bypasses the setup code and directly jumps to the code present after setup sectors(decompressor).

Quoted 6 lines

The existing setup protocol definitely allows
invoking an entry point which isn't 0x100000 (rather, the 32-bit entrypoint is defined by code32_start); I'm not sure how Eric's relocatable kernel patches (2.05 protocol) affect that, mostly because I haven't seen any boot loaders which actually use it so I can't comment on what their code looks like.

With relocatable patches, if a boot loader decides to load protected mode component at non-1MB address, then it shall have to modify code32_start to reflect the new location of protected mode code.

Thanks
Vivek

#92 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 31 lines · H. Peter Anvin
Quoted 30 lines · Jeremy Fitzhardinge

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

If we make 5 actually an ELF file, containing properly formed Ehdr, Phdrs (for all the mappings required), and the actual kernel decompressor, relocator and compressed kernel data, then it would be easy for the Xen domain builder to find that and use it as a basis for loading. I think it would just require the bzImage boot param block to contain an offset of the start of the ELF file. The contents of the ELF file would be in a form where the normal boot code could just jump over the ELF headers, directly into the segment data itself.

ie:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code (jumps directly into 5.3)
5. 32-bit self-decompressing kernel:
1. Ehdr
2. Phdrs for all necessary mappings
3. decompressor/relocator .text
4. compressed kernel data

Quoted 5 lines
Quoted 2 lines

Does that sound reasonable?

I don't know if that would break any programs that are currently bypassing the setup.

I think kexec bzImage loader will break. It bypasses the setup code and directly jumps to the code present after setup sectors(decompressor).

Quoted 6 lines

The existing setup protocol definitely allows
invoking an entry point which isn't 0x100000 (rather, the 32-bit entrypoint is defined by code32_start); I'm not sure how Eric's relocatable kernel patches (2.05 protocol) affect that, mostly because I haven't seen any boot loaders which actually use it so I can't comment on what their code looks like.

With relocatable patches, if a boot loader decides to load protected mode component at non-1MB address, then it shall have to modify code32_start to reflect the new location of protected mode code.

Thanks
Vivek

#93 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 32 lines · Vivek Goyal
Quoted 31 lines · H. Peter Anvin
Quoted 30 lines · Jeremy Fitzhardinge

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

If we make 5 actually an ELF file, containing properly formed Ehdr, Phdrs (for all the mappings required), and the actual kernel decompressor, relocator and compressed kernel data, then it would be easy for the Xen domain builder to find that and use it as a basis for loading. I think it would just require the bzImage boot param block to contain an offset of the start of the ELF file. The contents of the ELF file would be in a form where the normal boot code could just jump over the ELF headers, directly into the segment data itself.

ie:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code (jumps directly into 5.3)
5. 32-bit self-decompressing kernel:
1. Ehdr
2. Phdrs for all necessary mappings
3. decompressor/relocator .text
4. compressed kernel data

Quoted 5 lines
Quoted 5 lines
Quoted 2 lines

Does that sound reasonable?

I don't know if that would break any programs that are currently bypassing the setup.

I think everything will break, unless we make 5.1 and 5.2 into 4.2 and 4.3. In the above design.

Quoted 2 lines

I think kexec bzImage loader will break. It bypasses the setup code and directly jumps to the code present after setup sectors(decompressor).

Quite likely. The boot sector except for a handful of bytes actually
goes unused so we can put extra header information there, I actually have patches for placing an ELF header there.

If we wanted to do an ELF header in the middle we would have to put it at the end of the setup sectors rather then the beginning of the raw protected mode kernel image.

Quoted 10 lines
Quoted 6 lines

The existing setup protocol definitely allows
invoking an entry point which isn't 0x100000 (rather, the 32-bit entrypoint is defined by code32_start); I'm not sure how Eric's relocatable kernel patches (2.05 protocol) affect that, mostly because I haven't seen any boot loaders which actually use it so I can't comment on what their code looks like.

With relocatable patches, if a boot loader decides to load protected mode component at non-1MB address, then it shall have to modify code32_start to reflect the new location of protected mode code.

Yes. And this aspect of the relocatable kernel is all Vivek.

Eric

#94 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Vivek Goyal
Quoted 32 lines · Vivek Goyal
Quoted 31 lines · H. Peter Anvin
Quoted 30 lines · Jeremy Fitzhardinge

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

If we make 5 actually an ELF file, containing properly formed Ehdr, Phdrs (for all the mappings required), and the actual kernel decompressor, relocator and compressed kernel data, then it would be easy for the Xen domain builder to find that and use it as a basis for loading. I think it would just require the bzImage boot param block to contain an offset of the start of the ELF file. The contents of the ELF file would be in a form where the normal boot code could just jump over the ELF headers, directly into the segment data itself.

ie:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code (jumps directly into 5.3)
5. 32-bit self-decompressing kernel:
1. Ehdr
2. Phdrs for all necessary mappings
3. decompressor/relocator .text
4. compressed kernel data

Quoted 5 lines
Quoted 5 lines
Quoted 2 lines

Does that sound reasonable?

I don't know if that would break any programs that are currently bypassing the setup.

I think everything will break, unless we make 5.1 and 5.2 into 4.2 and 4.3. In the above design.

Quoted 2 lines

I think kexec bzImage loader will break. It bypasses the setup code and directly jumps to the code present after setup sectors(decompressor).

Quite likely. The boot sector except for a handful of bytes actually
goes unused so we can put extra header information there, I actually have patches for placing an ELF header there.

If we wanted to do an ELF header in the middle we would have to put it at the end of the setup sectors rather then the beginning of the raw protected mode kernel image.

Quoted 10 lines
Quoted 6 lines

The existing setup protocol definitely allows
invoking an entry point which isn't 0x100000 (rather, the 32-bit entrypoint is defined by code32_start); I'm not sure how Eric's relocatable kernel patches (2.05 protocol) affect that, mostly because I haven't seen any boot loaders which actually use it so I can't comment on what their code looks like.

With relocatable patches, if a boot loader decides to load protected mode component at non-1MB address, then it shall have to modify code32_start to reflect the new location of protected mode code.

Yes. And this aspect of the relocatable kernel is all Vivek.

Eric

#95 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 47 lines · Eric W. Biederman
Quoted 33 lines · Vivek Goyal
Quoted 31 lines · H. Peter Anvin
Quoted 29 lines · Jeremy Fitzhardinge

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

If we make 5 actually an ELF file, containing properly formed Ehdr, Phdrs (for all the mappings required), and the actual kernel decompressor, relocator and compressed kernel data, then it would be easy for the Xen domain builder to find that and use it as a basis for loading. I think it would just require the bzImage boot param block to contain an offset of the start of the ELF file. The contents of the ELF file would be in a form where the normal boot code could just jump over the ELF headers, directly into the segment data itself.

ie:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code (jumps directly into 5.3)
5. 32-bit self-decompressing kernel:
1. Ehdr
2. Phdrs for all necessary mappings
3. decompressor/relocator .text
4. compressed kernel data

Quoted 6 lines
Quoted 6 lines
Quoted 3 lines

Does that sound reasonable?

I don't know if that would break any programs that are currently bypassing the setup.

I think everything will break, unless we make 5.1 and 5.2 into 4.2 and 4.3. In the above design.

Quoted 7 lines
Quoted 3 lines

I think kexec bzImage loader will break. It bypasses the setup code and directly jumps to the code present after setup sectors(decompressor).

Quite likely. The boot sector except for a handful of bytes actually
goes unused so we can put extra header information there, I actually have patches for placing an ELF header there.

OK, whatever you think will work. But I do think it should be a proper ELF file with a correct magic number, so that you can just point an ELF file parser at it and have it work (which means, of course, that all the file offsets are offsets from the start of the Ehdr, rather than from the start of the bzImage).

You haven't specifically commented on using the Phdrs as a way of specifying the mappings required for decompression and early kernel execution. It seems pretty natural to me, but I guess that raises the general question of what execution environment the kernel can expect to find itself in, and which modes of booting will actually enable paging and establish any kinds of mapping at all.

In the Xen case, its obviously the domain builder who creates the mappings, and we can easily implement p != v mappings. But when booting native, presumably paging is off at this stage, and only identity maps can be implemented. I guess the rough rule is that if paging is enabled on entry, the kernel should expect all the bzImage mappings to be in place, but if paging is off, well, the question is moot.

J

#100 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 47 lines · Eric W. Biederman
Quoted 33 lines · Vivek Goyal
Quoted 31 lines · H. Peter Anvin
Quoted 29 lines · Jeremy Fitzhardinge

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

If we make 5 actually an ELF file, containing properly formed Ehdr, Phdrs (for all the mappings required), and the actual kernel decompressor, relocator and compressed kernel data, then it would be easy for the Xen domain builder to find that and use it as a basis for loading. I think it would just require the bzImage boot param block to contain an offset of the start of the ELF file. The contents of the ELF file would be in a form where the normal boot code could just jump over the ELF headers, directly into the segment data itself.

ie:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code (jumps directly into 5.3)
5. 32-bit self-decompressing kernel:
1. Ehdr
2. Phdrs for all necessary mappings
3. decompressor/relocator .text
4. compressed kernel data

Quoted 6 lines
Quoted 6 lines
Quoted 3 lines

Does that sound reasonable?

I don't know if that would break any programs that are currently bypassing the setup.

I think everything will break, unless we make 5.1 and 5.2 into 4.2 and 4.3. In the above design.

Quoted 7 lines
Quoted 3 lines

I think kexec bzImage loader will break. It bypasses the setup code and directly jumps to the code present after setup sectors(decompressor).

Quite likely. The boot sector except for a handful of bytes actually
goes unused so we can put extra header information there, I actually have patches for placing an ELF header there.

OK, whatever you think will work. But I do think it should be a proper ELF file with a correct magic number, so that you can just point an ELF file parser at it and have it work (which means, of course, that all the file offsets are offsets from the start of the Ehdr, rather than from the start of the bzImage).

You haven't specifically commented on using the Phdrs as a way of specifying the mappings required for decompression and early kernel execution. It seems pretty natural to me, but I guess that raises the general question of what execution environment the kernel can expect to find itself in, and which modes of booting will actually enable paging and establish any kinds of mapping at all.

In the Xen case, its obviously the domain builder who creates the mappings, and we can easily implement p != v mappings. But when booting native, presumably paging is off at this stage, and only identity maps can be implemented. I guess the rough rule is that if paging is enabled on entry, the kernel should expect all the bzImage mappings to be in place, but if paging is off, well, the question is moot.

J

#96 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 5 lines · Jeremy Fitzhardinge

OK, whatever you think will work. But I do think it should be a proper ELF file with a correct magic number, so that you can just point an ELF file parser at it and have it work (which means, of course, that all the file offsets are offsets from the start of the Ehdr, rather than from the start of the bzImage).

Yes. I guess in this context, I am generally for building the ELF headers by hand instead of with a linker script, because then we know exactly what is happening and can ensure everything is just so.

Quoted 6 lines

You haven't specifically commented on using the Phdrs as a way of specifying the mappings required for decompression and early kernel execution. It seems pretty natural to me, but I guess that raises the general question of what execution environment the kernel can expect to find itself in, and which modes of booting will actually enable paging and establish any kinds of mapping at all.

Sorry, for not being clear I have been expecting to do this for years, it is one of the reasons I keep coming back to putting an ELF header on the bzImage. arch/x86_64/kernel already does this to some extent as it has to setup up some identity page mappings for itself in the case it has to do the switch from real to protected mode itself.

Quoted 6 lines

In the Xen case, its obviously the domain builder who creates the mappings, and we can easily implement p != v mappings. But when booting native, presumably paging is off at this stage, and only identity maps can be implemented. I guess the rough rule is that if paging is enabled on entry, the kernel should expect all the bzImage mappings to be in place, but if paging is off, well, the question is moot.

Right. Except that there is a bit of a catch 22 in the para-virtualized environments of setting up the page tables, I'm not at all certain what the gain of setting up p != v mappings are.

Having just written some C code that runs fairly successfully in p != v, on arch/i386 I'm not too concerned. arch/x86_64 ought to work with a similar level of effort although the expectations there are a little different. So while I don't necessarily considering running in p != v when compiled to run at v general it should work for the cases we are interested in. Setting up the page tables for arch/x86_64 will be more interesting.

Part of what I find compelling about this is our initial page tables for linux have always had more going on than the virtual addresses just being at a constant offset from of the physical addresses, so the actions of the current domain builders have me concerned that they may be violating some early linux booting assumptions and are currently just getting lucky. Moving the page table setup code into the kernel removes that dependency from the domain builders.

Eric

#97 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 5 lines · Jeremy Fitzhardinge

OK, whatever you think will work. But I do think it should be a proper ELF file with a correct magic number, so that you can just point an ELF file parser at it and have it work (which means, of course, that all the file offsets are offsets from the start of the Ehdr, rather than from the start of the bzImage).

Yes. I guess in this context, I am generally for building the ELF headers by hand instead of with a linker script, because then we know exactly what is happening and can ensure everything is just so.

Quoted 6 lines

You haven't specifically commented on using the Phdrs as a way of specifying the mappings required for decompression and early kernel execution. It seems pretty natural to me, but I guess that raises the general question of what execution environment the kernel can expect to find itself in, and which modes of booting will actually enable paging and establish any kinds of mapping at all.

Sorry, for not being clear I have been expecting to do this for years, it is one of the reasons I keep coming back to putting an ELF header on the bzImage. arch/x86_64/kernel already does this to some extent as it has to setup up some identity page mappings for itself in the case it has to do the switch from real to protected mode itself.

Quoted 6 lines

In the Xen case, its obviously the domain builder who creates the mappings, and we can easily implement p != v mappings. But when booting native, presumably paging is off at this stage, and only identity maps can be implemented. I guess the rough rule is that if paging is enabled on entry, the kernel should expect all the bzImage mappings to be in place, but if paging is off, well, the question is moot.

Right. Except that there is a bit of a catch 22 in the para-virtualized environments of setting up the page tables, I'm not at all certain what the gain of setting up p != v mappings are.

Having just written some C code that runs fairly successfully in p != v, on arch/i386 I'm not too concerned. arch/x86_64 ought to work with a similar level of effort although the expectations there are a little different. So while I don't necessarily considering running in p != v when compiled to run at v general it should work for the cases we are interested in. Setting up the page tables for arch/x86_64 will be more interesting.

Part of what I find compelling about this is our initial page tables for linux have always had more going on than the virtual addresses just being at a constant offset from of the physical addresses, so the actions of the current domain builders have me concerned that they may be violating some early linux booting assumptions and are currently just getting lucky. Moving the page table setup code into the kernel removes that dependency from the domain builders.

Eric

#98 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 4 lines · Eric W. Biederman

Yes. I guess in this context, I am generally for building the ELF headers by hand instead of with a linker script, because then we know exactly what is happening and can ensure everything is just so.

Yes, it seems easiest - particularly given how flaky binutils can get when you really try to control its ELF generation.

Quoted 4 lines

Sorry, for not being clear I have been expecting to do this for years, it is one of the reasons I keep coming back to putting an ELF header on the bzImage.

OK. It seems obvious, but I just wanted to make sure ;)

Quoted 8 lines
Quoted 7 lines

In the Xen case, its obviously the domain builder who creates the mappings, and we can easily implement p != v mappings. But when booting native, presumably paging is off at this stage, and only identity maps can be implemented. I guess the rough rule is that if paging is enabled on entry, the kernel should expect all the bzImage mappings to be in place, but if paging is off, well, the question is moot.

Quoted 4 lines

Right. Except that there is a bit of a catch 22 in the para-virtualized environments of setting up the page tables, I'm not at all certain what the gain of setting up p != v mappings are.

Well, that's more or less it. If the decompressor ends up jumping to startup_32, and that immediately goes into xen_start_kernel(), then we're still running on the initial bzImage p=v pagetables. At the moment, when the domain builder maps the kernel's vmlinux to the vaddrs in its Phdrs, so there's no need to do any more boot-time pagetable manipulation. If we come out of bzImage with only identity mappings, then obviously the Xen case will need to do the same pagetable setup as the native case - which is good so long as we can work out how to share the code to do so.

For i386, it looks like this will be tricky because at this point:

* we're not running at the linked address, so C code will be tricky and non-standard
* we need to deal with multiple hypervisors and their constraints on what can be in a pagetable
* we could be running with no paging, or paging in either non-PAE or PAE modes

Writing some code which can deal with all of those at once will be an interesting exercise.

Quoted 7 lines

Part of what I find compelling about this is our initial page tables for linux have always had more going on than the virtual addresses just being at a constant offset from of the physical addresses, so the actions of the current domain builders have me concerned that they may be violating some early linux booting assumptions and are currently just getting lucky. Moving the page table setup code into the kernel removes that dependency from the domain builders.

The nice thing about having the domain builder create the pagetables is that it turns it from a tricky bootstrap problem into a relatively easy job. The main thing is that the domain builder can create a scaffolding pagetable which is enough to get everything started. Once you have that in place, its pretty easy to update it to set precisely the right bits in the ptes, etc.

It also means that the path for Xen vs native will be more similar, because the bzImage code won't need to deal with pagetable setup at all:
for native it won't matter, and for Xen it has already been done. It only matters once we hit the 32-bit kernel-proper code, and we diverge at that point anyway.

J

#99 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 4 lines · Eric W. Biederman

Yes. I guess in this context, I am generally for building the ELF headers by hand instead of with a linker script, because then we know exactly what is happening and can ensure everything is just so.

Yes, it seems easiest - particularly given how flaky binutils can get when you really try to control its ELF generation.

Quoted 4 lines

Sorry, for not being clear I have been expecting to do this for years, it is one of the reasons I keep coming back to putting an ELF header on the bzImage.

OK. It seems obvious, but I just wanted to make sure ;)

Quoted 8 lines
Quoted 7 lines

In the Xen case, its obviously the domain builder who creates the mappings, and we can easily implement p != v mappings. But when booting native, presumably paging is off at this stage, and only identity maps can be implemented. I guess the rough rule is that if paging is enabled on entry, the kernel should expect all the bzImage mappings to be in place, but if paging is off, well, the question is moot.

Quoted 4 lines

Right. Except that there is a bit of a catch 22 in the para-virtualized environments of setting up the page tables, I'm not at all certain what the gain of setting up p != v mappings are.

Well, that's more or less it. If the decompressor ends up jumping to startup_32, and that immediately goes into xen_start_kernel(), then we're still running on the initial bzImage p=v pagetables. At the moment, when the domain builder maps the kernel's vmlinux to the vaddrs in its Phdrs, so there's no need to do any more boot-time pagetable manipulation. If we come out of bzImage with only identity mappings, then obviously the Xen case will need to do the same pagetable setup as the native case - which is good so long as we can work out how to share the code to do so.

For i386, it looks like this will be tricky because at this point:

* we're not running at the linked address, so C code will be tricky and non-standard
* we need to deal with multiple hypervisors and their constraints on what can be in a pagetable
* we could be running with no paging, or paging in either non-PAE or PAE modes

Writing some code which can deal with all of those at once will be an interesting exercise.

Quoted 7 lines

Part of what I find compelling about this is our initial page tables for linux have always had more going on than the virtual addresses just being at a constant offset from of the physical addresses, so the actions of the current domain builders have me concerned that they may be violating some early linux booting assumptions and are currently just getting lucky. Moving the page table setup code into the kernel removes that dependency from the domain builders.

The nice thing about having the domain builder create the pagetables is that it turns it from a tricky bootstrap problem into a relatively easy job. The main thing is that the domain builder can create a scaffolding pagetable which is enough to get everything started. Once you have that in place, its pretty easy to update it to set precisely the right bits in the ptes, etc.

It also means that the path for Xen vs native will be more similar, because the bzImage code won't need to deal with pagetable setup at all:
for native it won't matter, and for Xen it has already been done. It only matters once we hit the 32-bit kernel-proper code, and we diverge at that point anyway.

J

#101 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 5 lines · Eric W. Biederman
Quoted 3 lines · Vivek Goyal
Quoted 2 lines · H. Peter Anvin
Quoted 1 line · Jeremy Fitzhardinge
Quoted 8 lines
Quoted 8 lines
Quoted 8 lines
Quoted 8 lines

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

Eric,

With the latest change that make vmlinux to be elf64 and make bzImage do switch to 64bit long mode, the kernel started via kexec can not get VGA console. but the serial console works well. I wonder if the setup.S is skipped in bzImage via kexec path.

or i missed sth?

#!/bin/bash
./kexec -t bzImage -l bzImage_2.6.22_k8.1 --command-line="apic=debug acpi_dbg_level=0x00000007 pci=routeirq snd-hda-intel.enable_msi=1 ramdisk_size=65536 root=/dev/ram0 rw ip=dhcp console=tty0 console=ttyS0,9600n8" --ramdisk=mydisk8_x86_64.gz

YH

#102 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 5 lines · Eric W. Biederman
Quoted 3 lines · Vivek Goyal
Quoted 2 lines · H. Peter Anvin
Quoted 1 line · Jeremy Fitzhardinge
Quoted 8 lines
Quoted 8 lines
Quoted 8 lines
Quoted 8 lines

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

Eric,

With the latest change that make vmlinux to be elf64 and make bzImage do switch to 64bit long mode, the kernel started via kexec can not get VGA console. but the serial console works well. I wonder if the setup.S is skipped in bzImage via kexec path.

or i missed sth?

#!/bin/bash
./kexec -t bzImage -l bzImage_2.6.22_k8.1 --command-line="apic=debug acpi_dbg_level=0x00000007 pci=routeirq snd-hda-intel.enable_msi=1 ramdisk_size=65536 root=/dev/ram0 rw ip=dhcp console=tty0 console=ttyS0,9600n8" --ramdisk=mydisk8_x86_64.gz

YH

#103 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 6 lines · yhlu

Eric,

With the latest change that make vmlinux to be elf64 and make bzImage do switch to 64bit long mode, the kernel started via kexec can not get VGA console. but the serial console works well. I wonder if the setup.S is skipped in bzImage via kexec path.

Yes. setup.S has always been skipped by bzImage via the kexec path unless you explicitly tell /sbin/kexec to use the 16bit entry point.

Is not having a VGA console a new thing, or it something you just noticed?

Eric

#104 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu

Eric,

With the latest change that make vmlinux to be elf64 and make bzImage do switch to 64bit long mode, the kernel started via kexec can not get VGA console. but the serial console works well. I wonder if the setup.S is skipped in bzImage via kexec path.

Yes. setup.S has always been skipped by bzImage via the kexec path unless you explicitly tell /sbin/kexec to use the 16bit entry point.

Is not having a VGA console a new thing, or it something you just noticed?

Eric

#186 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 15 lines · yhlu
Quoted 5 lines · Eric W. Biederman
Quoted 3 lines · Vivek Goyal
Quoted 2 lines · H. Peter Anvin
Quoted 1 line · Jeremy Fitzhardinge
Quoted 8 lines
Quoted 8 lines
Quoted 8 lines
Quoted 8 lines

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

Quoted 9 lines

Eric,

With the latest change that make vmlinux to be elf64 and make bzImage do switch to 64bit long mode, the kernel started via kexec can not get VGA console. but the serial console works well. I wonder if the setup.S is skipped in bzImage via kexec path.

or i missed sth?

Hi,

setup.S is never executed while doing kexec (unless somebody chooses to do a real mode entry) and these patches don't change this beahviour.

Tomorrow I will test VGA behaviour on my machine. Are you using some special frame buffer mode etc?

Thanks
Vivek

#187 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 15 lines · yhlu
Quoted 5 lines · Eric W. Biederman
Quoted 3 lines · Vivek Goyal
Quoted 2 lines · H. Peter Anvin
Quoted 1 line · Jeremy Fitzhardinge
Quoted 8 lines
Quoted 8 lines
Quoted 8 lines
Quoted 8 lines

So the bzImage structure is currently:

1. old-style boot sector
2. old-style boot info, followed by 0xaa55 at the end of the sector
3. the HdrS boot param block
4. setup.S boot code
5. the self-decompressing kernel

Quoted 9 lines

Eric,

With the latest change that make vmlinux to be elf64 and make bzImage do switch to 64bit long mode, the kernel started via kexec can not get VGA console. but the serial console works well. I wonder if the setup.S is skipped in bzImage via kexec path.

or i missed sth?

Hi,

setup.S is never executed while doing kexec (unless somebody chooses to do a real mode entry) and these patches don't change this beahviour.

Tomorrow I will test VGA behaviour on my machine. Are you using some special frame buffer mode etc?

Thanks
Vivek

#105 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 7 lines · Eric W. Biederman

Yes. setup.S has always been skipped by bzImage via the kexec path unless you explicitly tell /sbin/kexec to use the 16bit entry point.

Is not having a VGA console a new thing, or it something you just noticed?

Eric

before the changes, it works well.

with --real-mode, it will reset the machine.
with --reset-vga, i will get

Kernel alive
kernel direct mapping tables up to 100000000 @ 8000-d000

on VGA monitor.

YH

#188 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Vivek Goyal
Quoted 6 lines · Vivek Goyal

setup.S is never executed while doing kexec (unless somebody chooses to do a real mode entry) and these patches don't change this beahviour.

Tomorrow I will test VGA behaviour on my machine. Are you using some special frame buffer mode etc?

I disabled the FB in the kernel.

YH

#189 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Vivek Goyal
Quoted 6 lines · Vivek Goyal

setup.S is never executed while doing kexec (unless somebody chooses to do a real mode entry) and these patches don't change this beahviour.

Tomorrow I will test VGA behaviour on my machine. Are you using some special frame buffer mode etc?

I disabled the FB in the kernel.

YH

#106 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu

Eric,

i tried to load vmlinux with kexec and got
Ramdisks not supported with generic elf arguments

So i use mkelfImage with my patch ( convert elf64 to elf32) to make another elf32. and loaded with kexec and can not get vga console too. ---serial console works well.

the mkelfImage 2.7 patch is at
http://72.14.253.104/search?q=cache:fuxOvFw3ZIIJ:lists.osdl.org/pipermail/fastboot/attachments/20061108/009064a6/attachment.obj+mkelfImage+2.7+patch&hl=en&ct=clnk&cd=4&gl=us

So the problem is not bzImage related, but in somewhere in vmlinux.

YH

#107 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu

Eric,

i tried to load vmlinux with kexec and got
Ramdisks not supported with generic elf arguments

So i use mkelfImage with my patch ( convert elf64 to elf32) to make another elf32. and loaded with kexec and can not get vga console too. ---serial console works well.

the mkelfImage 2.7 patch is at
http://72.14.253.104/search?q=cache:fuxOvFw3ZIIJ:lists.osdl.org/pipermail/fastboot/attachments/20061108/009064a6/attachment.obj+mkelfImage+2.7+patch&hl=en&ct=clnk&cd=4&gl=us

So the problem is not bzImage related, but in somewhere in vmlinux.

YH

#110 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 5 lines · yhlu

Eric,

i tried to load vmlinux with kexec and got
Ramdisks not supported with generic elf arguments

Quoted 8 lines

So i use mkelfImage with my patch ( convert elf64 to elf32) to make another elf32. and loaded with kexec and can not get vga console too. ---serial console works well.

the mkelfImage 2.7 patch is at
http://72.14.253.104/search?q=cache:fuxOvFw3ZIIJ:lists.osdl.org/pipermail/fastboot/attachments/20061108/009064a6/attachment.obj+mkelfImage+2.7+patch&hl=en&ct=clnk&cd=4&gl=us

So the problem is not bzImage related, but in somewhere in vmlinux.

Odd. Is it specifically these patches?
Or is it just the recent kernel from Linus?

You might try a git-bisect, or if it is just these patches walking through them one-by-one.

Eric

#111 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 5 lines · yhlu

Eric,

i tried to load vmlinux with kexec and got
Ramdisks not supported with generic elf arguments

Quoted 8 lines

So i use mkelfImage with my patch ( convert elf64 to elf32) to make another elf32. and loaded with kexec and can not get vga console too. ---serial console works well.

the mkelfImage 2.7 patch is at
http://72.14.253.104/search?q=cache:fuxOvFw3ZIIJ:lists.osdl.org/pipermail/fastboot/attachments/20061108/009064a6/attachment.obj+mkelfImage+2.7+patch&hl=en&ct=clnk&cd=4&gl=us

So the problem is not bzImage related, but in somewhere in vmlinux.

Odd. Is it specifically these patches?
Or is it just the recent kernel from Linus?

You might try a git-bisect, or if it is just these patches walking through them one-by-one.

Eric

Acked-by Ingo Molnar
#112 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 2 lines · Eric W. Biederman

You might try a git-bisect, or if it is just these patches walking through them one-by-one.

f82af20e1a028e16b9bb11da081fa1148d40fa6a is first bad commit commit f82af20e1a028e16b9bb11da081fa1148d40fa6a

Author: Gerd Hoffmann <[email protected]>
Date:   Wed May 2 19:27:19 2007 +0200

[PATCH] x86-64: ignore vgacon if hardware not present

Avoid trying to set up vgacon if there's no vga hardware present.

YH

Acked-by Ingo Molnar
#113 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 2 lines · Eric W. Biederman

You might try a git-bisect, or if it is just these patches walking through them one-by-one.

f82af20e1a028e16b9bb11da081fa1148d40fa6a is first bad commit commit f82af20e1a028e16b9bb11da081fa1148d40fa6a

Author: Gerd Hoffmann <[email protected]>
Date:   Wed May 2 19:27:19 2007 +0200

[PATCH] x86-64: ignore vgacon if hardware not present

Avoid trying to set up vgacon if there's no vga hardware present.

YH

#114 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 11 lines · yhlu
Quoted 2 lines · Eric W. Biederman

You might try a git-bisect, or if it is just these patches walking through them one-by-one.

f82af20e1a028e16b9bb11da081fa1148d40fa6a is first bad commit commit f82af20e1a028e16b9bb11da081fa1148d40fa6a

Author: Gerd Hoffmann <[email protected]>
Date:   Wed May 2 19:27:19 2007 +0200

[PATCH] x86-64: ignore vgacon if hardware not present

Quoted 7 lines

Avoid trying to set up vgacon if there's no vga hardware present.

Interesting. I haven't really been following this thread, but doesn't it mean something isn't being initialized properly if this patch makes a difference?

J

#115 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 11 lines · yhlu
Quoted 2 lines · Eric W. Biederman

You might try a git-bisect, or if it is just these patches walking through them one-by-one.

f82af20e1a028e16b9bb11da081fa1148d40fa6a is first bad commit commit f82af20e1a028e16b9bb11da081fa1148d40fa6a

Author: Gerd Hoffmann <[email protected]>
Date:   Wed May 2 19:27:19 2007 +0200

[PATCH] x86-64: ignore vgacon if hardware not present

Quoted 7 lines

Avoid trying to set up vgacon if there's no vga hardware present.

Interesting. I haven't really been following this thread, but doesn't it mean something isn't being initialized properly if this patch makes a difference?

J

#116 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 5 lines · Jeremy Fitzhardinge

Interesting. I haven't really been following this thread, but doesn't it mean something isn't being initialized properly if this patch makes a difference?

Specifically boot_params.screen_info isn't being properly set up by the caller.

-hpa

#117 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Jeremy Fitzhardinge
Quoted 5 lines · Jeremy Fitzhardinge

Interesting. I haven't really been following this thread, but doesn't it mean something isn't being initialized properly if this patch makes a difference?

Specifically boot_params.screen_info isn't being properly set up by the caller.

-hpa

#118 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 3 lines · H. Peter Anvin

Jeremy Fitzhardinge wrote:
Specifically boot_params.screen_info isn't being properly set up by the caller.

will setup real_mode_data in kexec path?

YH

#119 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 3 lines · H. Peter Anvin

Jeremy Fitzhardinge wrote:
Specifically boot_params.screen_info isn't being properly set up by the caller.

will setup real_mode_data in kexec path?

YH

#120 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 6 lines · yhlu
Quoted 3 lines · H. Peter Anvin

Jeremy Fitzhardinge wrote:
Specifically boot_params.screen_info isn't being properly set up by the caller.

will setup real_mode_data in kexec path?

-ENOPARSE

-hpa

#121 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu
Quoted 3 lines · H. Peter Anvin

Jeremy Fitzhardinge wrote:
Specifically boot_params.screen_info isn't being properly set up by the caller.

will setup real_mode_data in kexec path?

-ENOPARSE

-hpa

#122 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 9 lines · H. Peter Anvin
Quoted 6 lines · yhlu
Quoted 3 lines · H. Peter Anvin

Jeremy Fitzhardinge wrote:
Specifically boot_params.screen_info isn't being properly set up by the caller.

will setup real_mode_data in kexec path?

-ENOPARSE

I believe YH is asking how we setup real_mode_data in /sbin/kexec. The setup is:

Quoted 9 lines
        real_mode->orig_x = 0;
        real_mode->orig_y = 0;
        real_mode->orig_video_page = 0;
        real_mode->orig_video_mode = 0;
        real_mode->orig_video_cols = 80;
        real_mode->orig_video_lines = 25;
        real_mode->orig_video_ega_bx = 0;
        real_mode->orig_video_isVGA = 1;
        real_mode->orig_video_points = 16;

Silly but generally safe.

More relevant because the code is in kernel we have:

arch/arm/kernel/setup.c:

Quoted 8 lines

struct screen_info screen_info = {
.orig_video_lines = 30,
.orig_video_cols = 80,
.orig_video_mode = 0,
.orig_video_ega_bx = 0,
.orig_video_isVGA = 1,
.orig_video_points = 8
};

arch/alpha/kernel/sys_sio.c:

Quoted 5 lines
	/* The AlphaBook1 has LCD video fixed at 800x600,
	   37 rows and 100 cols. */
	screen_info.orig_y = 37;
	screen_info.orig_video_cols = 100;
	screen_info.orig_video_lines = 37;

I expect I can find a few more examples where we specify video_cols and video_lines but we use video_mode == 0.

Going farther mode 0x00 is a BIOS 40x25 mode. So the patch below is not always safe even if we boot the bzImage. It is just highly unlikely anyone would start the kernel in 40x25 text mode.

Therefore I expect the test should test several additional fields, in particular video lines and columns before we decide that we have an uninitialized screen_info and give up.

Quoted 19 lines

commit f82af20e1a028e16b9bb11da081fa1148d40fa6a

Author: Gerd Hoffmann <[email protected]>
Date:   Wed May 2 19:27:19 2007 +0200

[PATCH] x86-64: ignore vgacon if hardware not present

Avoid trying to set up vgacon if there's no vga hardware present.

drivers/video/console/vgacon.c +0 -0
index 91a2078..3e67c34 100644

drivers/video/console/vgacon.c static const char *vgacon_startup(void) · line 378

Quoted 9 lines
drivers/video/console/vgacon.c +2 -1
@@ -371,7 +371,8 @@ static const char *vgacon_startup(void)
        }
 
        /* VGA16 modes are not handled by VGACON */
-       if ((ORIG_VIDEO_MODE == 0x0D) ||        /* 320x200/4 */
+       if ((ORIG_VIDEO_MODE == 0x00) ||        /* SCREEN_INFO not initialized */
+           (ORIG_VIDEO_MODE == 0x0D) ||        /* 320x200/4 */
            (ORIG_VIDEO_MODE == 0x0E) ||        /* 640x200/4 */
            (ORIG_VIDEO_MODE == 0x10) ||        /* 640x350/4 */
            (ORIG_VIDEO_MODE == 0x12) ||        /* 640x480/4 */

Eric

#123 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 9 lines · H. Peter Anvin
Quoted 6 lines · yhlu
Quoted 3 lines · H. Peter Anvin

Jeremy Fitzhardinge wrote:
Specifically boot_params.screen_info isn't being properly set up by the caller.

will setup real_mode_data in kexec path?

-ENOPARSE

I believe YH is asking how we setup real_mode_data in /sbin/kexec. The setup is:

Quoted 9 lines
        real_mode->orig_x = 0;
        real_mode->orig_y = 0;
        real_mode->orig_video_page = 0;
        real_mode->orig_video_mode = 0;
        real_mode->orig_video_cols = 80;
        real_mode->orig_video_lines = 25;
        real_mode->orig_video_ega_bx = 0;
        real_mode->orig_video_isVGA = 1;
        real_mode->orig_video_points = 16;

Silly but generally safe.

More relevant because the code is in kernel we have:

arch/arm/kernel/setup.c:

Quoted 8 lines

struct screen_info screen_info = {
.orig_video_lines = 30,
.orig_video_cols = 80,
.orig_video_mode = 0,
.orig_video_ega_bx = 0,
.orig_video_isVGA = 1,
.orig_video_points = 8
};

arch/alpha/kernel/sys_sio.c:

Quoted 5 lines
	/* The AlphaBook1 has LCD video fixed at 800x600,
	   37 rows and 100 cols. */
	screen_info.orig_y = 37;
	screen_info.orig_video_cols = 100;
	screen_info.orig_video_lines = 37;

I expect I can find a few more examples where we specify video_cols and video_lines but we use video_mode == 0.

Going farther mode 0x00 is a BIOS 40x25 mode. So the patch below is not always safe even if we boot the bzImage. It is just highly unlikely anyone would start the kernel in 40x25 text mode.

Therefore I expect the test should test several additional fields, in particular video lines and columns before we decide that we have an uninitialized screen_info and give up.

Quoted 19 lines

commit f82af20e1a028e16b9bb11da081fa1148d40fa6a

Author: Gerd Hoffmann <[email protected]>
Date:   Wed May 2 19:27:19 2007 +0200

[PATCH] x86-64: ignore vgacon if hardware not present

Avoid trying to set up vgacon if there's no vga hardware present.

drivers/video/console/vgacon.c +0 -0
index 91a2078..3e67c34 100644

drivers/video/console/vgacon.c static const char *vgacon_startup(void) · line 378

Quoted 9 lines
drivers/video/console/vgacon.c +2 -1
@@ -371,7 +371,8 @@ static const char *vgacon_startup(void)
        }
 
        /* VGA16 modes are not handled by VGACON */
-       if ((ORIG_VIDEO_MODE == 0x0D) ||        /* 320x200/4 */
+       if ((ORIG_VIDEO_MODE == 0x00) ||        /* SCREEN_INFO not initialized */
+           (ORIG_VIDEO_MODE == 0x0D) ||        /* 320x200/4 */
            (ORIG_VIDEO_MODE == 0x0E) ||        /* 640x200/4 */
            (ORIG_VIDEO_MODE == 0x10) ||        /* 640x350/4 */
            (ORIG_VIDEO_MODE == 0x12) ||        /* 640x480/4 */

Eric

#124 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 8 lines · Eric W. Biederman

I expect I can find a few more examples where we specify video_cols and video_lines but we use video_mode == 0.

Going farther mode 0x00 is a BIOS 40x25 mode. So the patch below is not always safe even if we boot the bzImage. It is just highly unlikely anyone would start the kernel in 40x25 text mode.

Mode 0x00 is, at least theoretically, BIOS 40x25 *grayscale*; this mode (and mode 0x02 which is the same thing in 80x25) were as far as I know only ever used with composite monitors off CGA cards, i.e. functionally never. Actual monochrome monitors used mode 0x07.

-hpa

#125 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 8 lines · Eric W. Biederman

I expect I can find a few more examples where we specify video_cols and video_lines but we use video_mode == 0.

Going farther mode 0x00 is a BIOS 40x25 mode. So the patch below is not always safe even if we boot the bzImage. It is just highly unlikely anyone would start the kernel in 40x25 text mode.

Mode 0x00 is, at least theoretically, BIOS 40x25 *grayscale*; this mode (and mode 0x02 which is the same thing in 80x25) were as far as I know only ever used with composite monitors off CGA cards, i.e. functionally never. Actual monochrome monitors used mode 0x07.

-hpa

#172 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 2 lines · Eric W. Biederman

"H. Peter Anvin" <[email protected]> writes:
I believe YH is asking how we setup real_mode_data in /sbin/kexec.

pxelinux:

SCREEN_INFO.orig_video_mode = 3 SCREEN_INFO.orig_x = 0
SCREEN_INFO.orig_y = 24
x86_boot_params[] :
0000: 00 18 ff ff 08 00 03 50 8c c8 03 00 8e c0 19 01 0010: 10 00 7c fb fc be 31 00 ac 20 c0 74 09 b4 0e bb 0020: 07 00 cd 10 eb f2 31 c0 cd 16 cd 19 ea f0 ff 00 0030: f0 44 69 72 65 63 74 20 62 6f 6f 74 15 00 10 00

current kexec:
SCREEN_INFO.orig_video_mode = 0 SCREEN_INFO.orig_x = 0
SCREEN_INFO.orig_y = 3
x86_boot_params[] :
0000: 00 03 00 fc 00 00 00 50 8c c8 00 00 8e c0 19 01 0010: 10 00 7c fb fc be 31 00 ac 20 c0 74 09 b4 0e bb 0020: 3f a3 00 16 eb f2 31 c0 cd 16 cd 19 ea f0 ff 00 0030: f0 44 69 72 65 63 74 20 62 6f 6f 74 15 00 20 00

YH

#173 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 2 lines · Eric W. Biederman

"H. Peter Anvin" <[email protected]> writes:
I believe YH is asking how we setup real_mode_data in /sbin/kexec.

pxelinux:

SCREEN_INFO.orig_video_mode = 3 SCREEN_INFO.orig_x = 0
SCREEN_INFO.orig_y = 24
x86_boot_params[] :
0000: 00 18 ff ff 08 00 03 50 8c c8 03 00 8e c0 19 01 0010: 10 00 7c fb fc be 31 00 ac 20 c0 74 09 b4 0e bb 0020: 07 00 cd 10 eb f2 31 c0 cd 16 cd 19 ea f0 ff 00 0030: f0 44 69 72 65 63 74 20 62 6f 6f 74 15 00 10 00

current kexec:
SCREEN_INFO.orig_video_mode = 0 SCREEN_INFO.orig_x = 0
SCREEN_INFO.orig_y = 3
x86_boot_params[] :
0000: 00 03 00 fc 00 00 00 50 8c c8 00 00 8e c0 19 01 0010: 10 00 7c fb fc be 31 00 ac 20 c0 74 09 b4 0e bb 0020: 3f a3 00 16 eb f2 31 c0 cd 16 cd 19 ea f0 ff 00 0030: f0 44 69 72 65 63 74 20 62 6f 6f 74 15 00 20 00

YH

#126 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 10 lines · H. Peter Anvin
Quoted 8 lines · Eric W. Biederman

I expect I can find a few more examples where we specify video_cols and video_lines but we use video_mode == 0.

Going farther mode 0x00 is a BIOS 40x25 mode. So the patch below is not always safe even if we boot the bzImage. It is just highly unlikely anyone would start the kernel in 40x25 text mode.

Quoted 4 lines

Mode 0x00 is, at least theoretically, BIOS 40x25 *grayscale*; this mode (and mode 0x02 which is the same thing in 80x25) were as far as I know only ever used with composite monitors off CGA cards, i.e. functionally never. Actual monochrome monitors used mode 0x07.

I agree. We are not at all likely to see it in practice. Even if my memory is correct and vga cards and non-monochrome cga cards supported that mode.

That doesn't mean checking for 0x00 is sufficient to detect an initialized struct screen_info, or a lack of a video screen.

We have in kernel historical precedent for using 0x00 as just meaning a text mode. I'm fairly certain that I looked I more closely I could find this convention of using 0x00 to mean a text mode on ia64, mips, and ppc, in addition to the instances I found on alpha, arm,

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

Eric

#127 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 10 lines · H. Peter Anvin
Quoted 8 lines · Eric W. Biederman

I expect I can find a few more examples where we specify video_cols and video_lines but we use video_mode == 0.

Going farther mode 0x00 is a BIOS 40x25 mode. So the patch below is not always safe even if we boot the bzImage. It is just highly unlikely anyone would start the kernel in 40x25 text mode.

Quoted 4 lines

Mode 0x00 is, at least theoretically, BIOS 40x25 *grayscale*; this mode (and mode 0x02 which is the same thing in 80x25) were as far as I know only ever used with composite monitors off CGA cards, i.e. functionally never. Actual monochrome monitors used mode 0x07.

I agree. We are not at all likely to see it in practice. Even if my memory is correct and vga cards and non-monochrome cga cards supported that mode.

That doesn't mean checking for 0x00 is sufficient to detect an initialized struct screen_info, or a lack of a video screen.

We have in kernel historical precedent for using 0x00 as just meaning a text mode. I'm fairly certain that I looked I more closely I could find this convention of using 0x00 to mean a text mode on ia64, mips, and ppc, in addition to the instances I found on alpha, arm,

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

Eric

#174 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 5 lines · yhlu

Eric,

i tried to load vmlinux with kexec and got
Ramdisks not supported with generic elf arguments

This message generally appears if you did not specify --args-linux on kexec command line while loading vmlinux.

Thanks
Vivek

#175 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 5 lines · yhlu

Eric,

i tried to load vmlinux with kexec and got
Ramdisks not supported with generic elf arguments

This message generally appears if you did not specify --args-linux on kexec command line while loading vmlinux.

Thanks
Vivek

#176 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 4 lines · Vivek Goyal

On Tue, May 08, 2007 at 11:51:35AM -0700, yhlu wrote:
This message generally appears if you did not specify --args-linux on kexec command line while loading vmlinux.

besides elf-x86_64, still need --args-linux to pass sth? but how to let it load ramdisk?

YH

#177 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Vivek Goyal
Quoted 4 lines · Vivek Goyal

On Tue, May 08, 2007 at 11:51:35AM -0700, yhlu wrote:
This message generally appears if you did not specify --args-linux on kexec command line while loading vmlinux.

besides elf-x86_64, still need --args-linux to pass sth? but how to let it load ramdisk?

YH

#178 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Vivek Goyal
Quoted 4 lines · Vivek Goyal

On Tue, May 08, 2007 at 11:51:35AM -0700, yhlu wrote:
This message generally appears if you did not specify --args-linux on kexec command line while loading vmlinux.

besides elf-x86_64, still need --args-linux to pass sth? but how to let it load ramdisk?

YH

#179 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Vivek Goyal
Quoted 4 lines · Vivek Goyal

On Tue, May 08, 2007 at 11:51:35AM -0700, yhlu wrote:
This message generally appears if you did not specify --args-linux on kexec command line while loading vmlinux.

besides elf-x86_64, still need --args-linux to pass sth? but how to let it load ramdisk?

YH

#128 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

YH

#129 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

YH

#130 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

YH

#180 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 7 lines · yhlu
Quoted 4 lines · Vivek Goyal

On Tue, May 08, 2007 at 11:51:35AM -0700, yhlu wrote:
This message generally appears if you did not specify --args-linux on kexec command line while loading vmlinux.

besides elf-x86_64, still need --args-linux to pass sth? but how to let it load ramdisk?

Same arguments just use --args-linux.

Basically the calling convention needs to be specified because there isn't a universal one, and /sbin/kexec can't yet detect vmlinux is linux.

Eric

#181 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 7 lines · yhlu
Quoted 4 lines · Vivek Goyal

On Tue, May 08, 2007 at 11:51:35AM -0700, yhlu wrote:
This message generally appears if you did not specify --args-linux on kexec command line while loading vmlinux.

besides elf-x86_64, still need --args-linux to pass sth? but how to let it load ramdisk?

Same arguments just use --args-linux.

Basically the calling convention needs to be specified because there isn't a universal one, and /sbin/kexec can't yet detect vmlinux is linux.

Eric

#182 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 7 lines · yhlu
Quoted 4 lines · Vivek Goyal

On Tue, May 08, 2007 at 11:51:35AM -0700, yhlu wrote:
This message generally appears if you did not specify --args-linux on kexec command line while loading vmlinux.

besides elf-x86_64, still need --args-linux to pass sth? but how to let it load ramdisk?

Same arguments just use --args-linux.

Basically the calling convention needs to be specified because there isn't a universal one, and /sbin/kexec can't yet detect vmlinux is linux.

Eric

#183 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 7 lines · yhlu
Quoted 4 lines · Vivek Goyal

On Tue, May 08, 2007 at 11:51:35AM -0700, yhlu wrote:
This message generally appears if you did not specify --args-linux on kexec command line while loading vmlinux.

besides elf-x86_64, still need --args-linux to pass sth? but how to let it load ramdisk?

Same arguments just use --args-linux.

Basically the calling convention needs to be specified because there isn't a universal one, and /sbin/kexec can't yet detect vmlinux is linux.

Eric

#184 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 7 lines · yhlu
Quoted 4 lines · Vivek Goyal

On Tue, May 08, 2007 at 11:51:35AM -0700, yhlu wrote:
This message generally appears if you did not specify --args-linux on kexec command line while loading vmlinux.

besides elf-x86_64, still need --args-linux to pass sth? but how to let it load ramdisk?

Same arguments just use --args-linux.

Basically the calling convention needs to be specified because there isn't a universal one, and /sbin/kexec can't yet detect vmlinux is linux.

Eric

#185 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 7 lines · yhlu
Quoted 4 lines · Vivek Goyal

On Tue, May 08, 2007 at 11:51:35AM -0700, yhlu wrote:
This message generally appears if you did not specify --args-linux on kexec command line while loading vmlinux.

besides elf-x86_64, still need --args-linux to pass sth? but how to let it load ramdisk?

Same arguments just use --args-linux.

Basically the calling convention needs to be specified because there isn't a universal one, and /sbin/kexec can't yet detect vmlinux is linux.

Eric

#131 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

There really isn't one, at least not given the current data structure; the data structure has an "isVGA" flag, but if that is 0 it's supposed to mean CGA/MDA/HGC/EGA, as opposed to VGA...

-hpa

#132 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

There really isn't one, at least not given the current data structure; the data structure has an "isVGA" flag, but if that is 0 it's supposed to mean CGA/MDA/HGC/EGA, as opposed to VGA...

-hpa

#133 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

There really isn't one, at least not given the current data structure; the data structure has an "isVGA" flag, but if that is 0 it's supposed to mean CGA/MDA/HGC/EGA, as opposed to VGA...

-hpa

#134 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

There really isn't one, at least not given the current data structure; the data structure has an "isVGA" flag, but if that is 0 it's supposed to mean CGA/MDA/HGC/EGA, as opposed to VGA...

-hpa

#135 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

There really isn't one, at least not given the current data structure; the data structure has an "isVGA" flag, but if that is 0 it's supposed to mean CGA/MDA/HGC/EGA, as opposed to VGA...

-hpa

#136 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

There really isn't one, at least not given the current data structure; the data structure has an "isVGA" flag, but if that is 0 it's supposed to mean CGA/MDA/HGC/EGA, as opposed to VGA...

-hpa

#137 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 10 lines · H. Peter Anvin
Quoted 5 lines · yhlu
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

There really isn't one, at least not given the current data structure; the data structure has an "isVGA" flag, but if that is 0 it's supposed to mean CGA/MDA/HGC/EGA, as opposed to VGA...

Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

-hpa

#138 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 10 lines · H. Peter Anvin
Quoted 5 lines · yhlu
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

There really isn't one, at least not given the current data structure; the data structure has an "isVGA" flag, but if that is 0 it's supposed to mean CGA/MDA/HGC/EGA, as opposed to VGA...

Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

-hpa

#139 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 10 lines · H. Peter Anvin
Quoted 5 lines · yhlu
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

There really isn't one, at least not given the current data structure; the data structure has an "isVGA" flag, but if that is 0 it's supposed to mean CGA/MDA/HGC/EGA, as opposed to VGA...

Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

-hpa

#140 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 10 lines · H. Peter Anvin
Quoted 5 lines · yhlu
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

There really isn't one, at least not given the current data structure; the data structure has an "isVGA" flag, but if that is 0 it's supposed to mean CGA/MDA/HGC/EGA, as opposed to VGA...

Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

-hpa

#141 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 10 lines · H. Peter Anvin
Quoted 5 lines · yhlu
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

There really isn't one, at least not given the current data structure; the data structure has an "isVGA" flag, but if that is 0 it's supposed to mean CGA/MDA/HGC/EGA, as opposed to VGA...

Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

-hpa

#142 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 10 lines · H. Peter Anvin
Quoted 5 lines · yhlu
Quoted 3 lines · Eric W. Biederman

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

need one good way to find if there is support vga console.

There really isn't one, at least not given the current data structure; the data structure has an "isVGA" flag, but if that is 0 it's supposed to mean CGA/MDA/HGC/EGA, as opposed to VGA...

Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

-hpa

#143 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 9 lines · H. Peter Anvin

H. Peter Anvin wrote:
Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

YH

#144 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 9 lines · H. Peter Anvin

H. Peter Anvin wrote:
Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

YH

#145 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 9 lines · H. Peter Anvin

H. Peter Anvin wrote:
Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

YH

#146 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 9 lines · H. Peter Anvin

H. Peter Anvin wrote:
Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

YH

#147 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 6 lines · yhlu
Quoted 5 lines · H. Peter Anvin

H. Peter Anvin wrote:
Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

Quoted 7 lines
Quoted 4 lines

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

A better way, probably, would be for the kernel to export the boot_params structure so kexec can reuse it.

-hpa

#148 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu
Quoted 5 lines · H. Peter Anvin

H. Peter Anvin wrote:
Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

Quoted 7 lines
Quoted 4 lines

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

A better way, probably, would be for the kernel to export the boot_params structure so kexec can reuse it.

-hpa

#149 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu
Quoted 5 lines · H. Peter Anvin

H. Peter Anvin wrote:
Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

Quoted 7 lines
Quoted 4 lines

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

A better way, probably, would be for the kernel to export the boot_params structure so kexec can reuse it.

-hpa

#150 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu
Quoted 5 lines · H. Peter Anvin

H. Peter Anvin wrote:
Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

Quoted 7 lines
Quoted 4 lines

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

A better way, probably, would be for the kernel to export the boot_params structure so kexec can reuse it.

-hpa

#151 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu
Quoted 5 lines · H. Peter Anvin

H. Peter Anvin wrote:
Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

Quoted 7 lines
Quoted 4 lines

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

A better way, probably, would be for the kernel to export the boot_params structure so kexec can reuse it.

-hpa

#152 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 3 lines · yhlu

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

BTW, welcome to the hell of bypassing setup.

-hpa

#153 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 3 lines · yhlu

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

BTW, welcome to the hell of bypassing setup.

-hpa

#154 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 3 lines · yhlu

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

BTW, welcome to the hell of bypassing setup.

-hpa

#155 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 3 lines · yhlu

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

BTW, welcome to the hell of bypassing setup.

-hpa

#156 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 3 lines · yhlu

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

BTW, welcome to the hell of bypassing setup.

-hpa

#157 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 6 lines · yhlu
Quoted 5 lines · H. Peter Anvin

H. Peter Anvin wrote:
Of course, one could argue that since all of those were obsolete by the time Linux was first created, that it probably doesn't matter and that isVGA == 0 pretty much means the more obvious thing.

Quoted 7 lines
Quoted 4 lines

MDA/HGC stuck around for quite a while for debugging, since it was non-conflicting with VGA, but even if it is, the reason people put it in their system is to have something that the OS doesn't readily see.

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

A better way, probably, would be for the kernel to export the boot_params structure so kexec can reuse it.

-hpa

#158 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to yhlu
Quoted 3 lines · yhlu

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

BTW, welcome to the hell of bypassing setup.

-hpa

#166 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman

Hi,

Quoted 3 lines

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

Like in the attached patch?

cheers,
Gerd

Refine SCREEN_INFO sanity check for vgacon initialization.

Checking video mode field only to see whenever SCREEN_INFO is initialized is not enougth, in some cases it is zero although a vga card is present. Lets additionally check cols and lines.

Cc Rusty Russell <[email protected]>
Cc Andi Kleen <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc Eric W. Biederman <[email protected]>
---
 drivers/video/console/vgacon.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
drivers/video/console/vgacon.c +7 -2
Index: vanilla-2.6.21-git11/drivers/video/console/vgacon.c
===================================================================
@@ -368,9 +368,14 @@ static const char *vgacon_startup(void)
 #endif
 	}
 
+	/* SCREEN_INFO initialized? */
+	if ((ORIG_VIDEO_MODE  == 0) &&
+	    (ORIG_VIDEO_LINES == 0) &&
+	    (ORIG_VIDEO_COLS  == 0))
+		goto no_vga;
+
 	/* VGA16 modes are not handled by VGACON */
-	if ((ORIG_VIDEO_MODE == 0x00) ||	/* SCREEN_INFO not initialized */
-	    (ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
+	if ((ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
 	    (ORIG_VIDEO_MODE == 0x0E) ||	/* 640x200/4 */
 	    (ORIG_VIDEO_MODE == 0x10) ||	/* 640x350/4 */
 	    (ORIG_VIDEO_MODE == 0x12) ||	/* 640x480/4 */

_______________________________________________
Virtualization mailing list
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https://lists.linux-foundation.org/mailman/listinfo/virtualization

#167 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman

Hi,

Quoted 3 lines

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

Like in the attached patch?

cheers,
Gerd

Refine SCREEN_INFO sanity check for vgacon initialization.

Checking video mode field only to see whenever SCREEN_INFO is initialized is not enougth, in some cases it is zero although a vga card is present. Lets additionally check cols and lines.

Cc Rusty Russell <[email protected]>
Cc Andi Kleen <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc Eric W. Biederman <[email protected]>
---
 drivers/video/console/vgacon.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
drivers/video/console/vgacon.c +7 -2
Index: vanilla-2.6.21-git11/drivers/video/console/vgacon.c
===================================================================
@@ -368,9 +368,14 @@ static const char *vgacon_startup(void)
 #endif
 	}
 
+	/* SCREEN_INFO initialized? */
+	if ((ORIG_VIDEO_MODE  == 0) &&
+	    (ORIG_VIDEO_LINES == 0) &&
+	    (ORIG_VIDEO_COLS  == 0))
+		goto no_vga;
+
 	/* VGA16 modes are not handled by VGACON */
-	if ((ORIG_VIDEO_MODE == 0x00) ||	/* SCREEN_INFO not initialized */
-	    (ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
+	if ((ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
 	    (ORIG_VIDEO_MODE == 0x0E) ||	/* 640x200/4 */
 	    (ORIG_VIDEO_MODE == 0x10) ||	/* 640x350/4 */
 	    (ORIG_VIDEO_MODE == 0x12) ||	/* 640x480/4 */
#159 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 6 lines · H. Peter Anvin
Quoted 3 lines · yhlu

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

BTW, welcome to the hell of bypassing setup.

Well in this case things are so very much better then attempting to us setup.S it isn't a real option.

In general BIOS calls just don't work reliably after linux has been running for a while.

As for YH's point it does look like there are a few ways to poke the linux kernel to see what is happening.

We can look in /proc/ioports and see what has reserved the video resources. That should give us a reasonable estimate of the video adapter. We can do an ioctl to the console and see how many lines and columns we have.

Reusing boot_params could be nice but if we have the information available in other ways digging it out that way is quite possibly better.

Eric

#160 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to H. Peter Anvin
Quoted 6 lines · H. Peter Anvin
Quoted 3 lines · yhlu

so the kexec tools need to scan the pci devices list, and find out how to set real_mode.isVGA and orig_video_mode, also need to parse the comand line about vga console.

BTW, welcome to the hell of bypassing setup.

Well in this case things are so very much better then attempting to us setup.S it isn't a real option.

In general BIOS calls just don't work reliably after linux has been running for a while.

As for YH's point it does look like there are a few ways to poke the linux kernel to see what is happening.

We can look in /proc/ioports and see what has reserved the video resources. That should give us a reasonable estimate of the video adapter. We can do an ioctl to the console and see how many lines and columns we have.

Reusing boot_params could be nice but if we have the information available in other ways digging it out that way is quite possibly better.

Eric

#168 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Gerd Hoffmann
Quoted 7 lines · Gerd Hoffmann

Hi,

Quoted 3 lines

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

Like in the attached patch?

Looks good to me.

Quoted 39 lines

cheers,
Gerd
Refine SCREEN_INFO sanity check for vgacon initialization.

Checking video mode field only to see whenever SCREEN_INFO is initialized is not enougth, in some cases it is zero although a vga card is present. Lets additionally check cols and lines.

Cc Rusty Russell <[email protected]>
Cc Andi Kleen <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc Eric W. Biederman <[email protected]>
---
 drivers/video/console/vgacon.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Index: vanilla-2.6.21-git11/drivers/video/console/vgacon.c
===================================================================

drivers/video/console/vgacon.c +7 -2
@@ -368,9 +368,14 @@ static const char *vgacon_startup(void)
 #endif
 	}
 
+	/* SCREEN_INFO initialized? */
+	if ((ORIG_VIDEO_MODE  == 0) &&
+	    (ORIG_VIDEO_LINES == 0) &&
+	    (ORIG_VIDEO_COLS  == 0))
+		goto no_vga;
+
 	/* VGA16 modes are not handled by VGACON */
- if ((ORIG_VIDEO_MODE == 0x00) || /* SCREEN_INFO not initialized */
-	    (ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
+	if ((ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
 	    (ORIG_VIDEO_MODE == 0x0E) ||	/* 640x200/4 */
 	    (ORIG_VIDEO_MODE == 0x10) ||	/* 640x350/4 */
 	    (ORIG_VIDEO_MODE == 0x12) ||	/* 640x480/4 */
#169 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Gerd Hoffmann
Quoted 7 lines · Gerd Hoffmann

Hi,

Quoted 3 lines

Since the whole point is to detect the case where we don't have a screen at all it makes sense to check several additional variables and make certain that they are all 0. Agreed?

Like in the attached patch?

Looks good to me.

Quoted 39 lines

cheers,
Gerd
Refine SCREEN_INFO sanity check for vgacon initialization.

Checking video mode field only to see whenever SCREEN_INFO is initialized is not enougth, in some cases it is zero although a vga card is present. Lets additionally check cols and lines.

Cc Rusty Russell <[email protected]>
Cc Andi Kleen <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc Eric W. Biederman <[email protected]>
---
 drivers/video/console/vgacon.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Index: vanilla-2.6.21-git11/drivers/video/console/vgacon.c
===================================================================

drivers/video/console/vgacon.c +7 -2
@@ -368,9 +368,14 @@ static const char *vgacon_startup(void)
 #endif
 	}
 
+	/* SCREEN_INFO initialized? */
+	if ((ORIG_VIDEO_MODE  == 0) &&
+	    (ORIG_VIDEO_LINES == 0) &&
+	    (ORIG_VIDEO_COLS  == 0))
+		goto no_vga;
+
 	/* VGA16 modes are not handled by VGACON */
- if ((ORIG_VIDEO_MODE == 0x00) || /* SCREEN_INFO not initialized */
-	    (ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
+	if ((ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
 	    (ORIG_VIDEO_MODE == 0x0E) ||	/* 640x200/4 */
 	    (ORIG_VIDEO_MODE == 0x10) ||	/* 640x350/4 */
 	    (ORIG_VIDEO_MODE == 0x12) ||	/* 640x480/4 */
#161 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 9 lines · Eric W. Biederman

"H. Peter Anvin" <[email protected]> writes:
We can look in /proc/ioports and see what has reserved the video resources. That should give us a reasonable estimate of the video adapter. We can do an ioctl to the console and see how many lines and columns we have.

Reusing boot_params could be nice but if we have the information available in other ways digging it out that way is quite possibly better.

Another path:
LiuxBIOS+elfboot+payload, and payload is compressed elf (vmlinux+initrd) via lzma.
and use kexec to boot final production kernel.
We don't need to use boot_params from the first tiny kernel.

YH

#162 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 9 lines · Eric W. Biederman

"H. Peter Anvin" <[email protected]> writes:
We can look in /proc/ioports and see what has reserved the video resources. That should give us a reasonable estimate of the video adapter. We can do an ioctl to the console and see how many lines and columns we have.

Reusing boot_params could be nice but if we have the information available in other ways digging it out that way is quite possibly better.

Another path:
LiuxBIOS+elfboot+payload, and payload is compressed elf (vmlinux+initrd) via lzma.
and use kexec to boot final production kernel.
We don't need to use boot_params from the first tiny kernel.

YH

#163 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 4 lines · [email protected] wrote:

Well in this case things are so very much better then attempting to us setup.S it isn't a real option.

Obviously not, but it was more of a comment on the apparent assumption that doing so would be simple.

-hpa

#164 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Eric W. Biederman
Quoted 4 lines · [email protected] wrote:

Well in this case things are so very much better then attempting to us setup.S it isn't a real option.

Obviously not, but it was more of a comment on the apparent assumption that doing so would be simple.

-hpa

#165 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

Quoted 2 lines · H. Peter Anvin

Obviously not, but it was more of a comment on the apparent assumption that doing so would be simple.

Reasonable comment then.

Eric

#170 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Gerd Hoffmann
Quoted 28 lines · Gerd Hoffmann

Refine SCREEN_INFO sanity check for vgacon initialization.

Checking video mode field only to see whenever SCREEN_INFO is initialized is not enougth, in some cases it is zero although a vga card is present. Lets additionally check cols and lines.

Cc Rusty Russell <[email protected]>
Cc Andi Kleen <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc Eric W. Biederman <[email protected]>
---
 drivers/video/console/vgacon.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Index: vanilla-2.6.21-git11/drivers/video/console/vgacon.c
===================================================================

drivers/video/console/vgacon.c +3 -0
@@ -368,9 +368,14 @@ static const char *vgacon_startup(void)
 #endif
        }
 
+       /* SCREEN_INFO initialized? */
+       if ((ORIG_VIDEO_MODE  == 0) &&
+           (ORIG_VIDEO_LINES == 0) &&

drivers/video/console/vgacon.c static const char *vgacon_startup(void) · line 381

Quoted 10 lines
drivers/video/console/vgacon.c +4 -2
+           (ORIG_VIDEO_COLS  == 0))
+               goto no_vga;
+
        /* VGA16 modes are not handled by VGACON */
-       if ((ORIG_VIDEO_MODE == 0x00) ||        /* SCREEN_INFO not initialized */
-           (ORIG_VIDEO_MODE == 0x0D) ||        /* 320x200/4 */
+       if ((ORIG_VIDEO_MODE == 0x0D) ||        /* 320x200/4 */
            (ORIG_VIDEO_MODE == 0x0E) ||        /* 640x200/4 */
            (ORIG_VIDEO_MODE == 0x10) ||        /* 640x350/4 */
            (ORIG_VIDEO_MODE == 0x12) ||        /* 640x480/4 */

it works.

YH

#171 lore raw

Re: [patches] [PATCH] [21/22] x86_64: Extend bzImage protocol for relocatable bzImage

In reply to Gerd Hoffmann
Quoted 28 lines · Gerd Hoffmann

Refine SCREEN_INFO sanity check for vgacon initialization.

Checking video mode field only to see whenever SCREEN_INFO is initialized is not enougth, in some cases it is zero although a vga card is present. Lets additionally check cols and lines.

Cc Rusty Russell <[email protected]>
Cc Andi Kleen <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc Eric W. Biederman <[email protected]>
---
 drivers/video/console/vgacon.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Index: vanilla-2.6.21-git11/drivers/video/console/vgacon.c
===================================================================

drivers/video/console/vgacon.c +3 -0
@@ -368,9 +368,14 @@ static const char *vgacon_startup(void)
 #endif
        }
 
+       /* SCREEN_INFO initialized? */
+       if ((ORIG_VIDEO_MODE  == 0) &&
+           (ORIG_VIDEO_LINES == 0) &&

drivers/video/console/vgacon.c static const char *vgacon_startup(void) · line 381

Quoted 10 lines
drivers/video/console/vgacon.c +4 -2
+           (ORIG_VIDEO_COLS  == 0))
+               goto no_vga;
+
        /* VGA16 modes are not handled by VGACON */
-       if ((ORIG_VIDEO_MODE == 0x00) ||        /* SCREEN_INFO not initialized */
-           (ORIG_VIDEO_MODE == 0x0D) ||        /* 320x200/4 */
+       if ((ORIG_VIDEO_MODE == 0x0D) ||        /* 320x200/4 */
            (ORIG_VIDEO_MODE == 0x0E) ||        /* 640x200/4 */
            (ORIG_VIDEO_MODE == 0x10) ||        /* 640x350/4 */
            (ORIG_VIDEO_MODE == 0x12) ||        /* 640x480/4 */

it works.

YH