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Reflect recent changes in kdump documentation

PATCH In review Bernhard Walle 2 participants 5 messages Sep 9, 2007

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Bernhard Walle

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#0 lore raw

cover Reflect recent changes in kdump documentation

This patch series reflects some recent changes that have been made on kdump also in the documentation. See the description of the patches itself.

Signed-off-by Bernhard Walle <[email protected]>
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#1 lore raw

PATCH 1/3 Express relocatability of kernel on x86_64 in documentation

This patch adapts the Documentation/kdump/kdump.txt file to express the fact that the x86_64 kernel is now also relocatable. This makes i386 and x86_64 now behave the same, simplifying the documentation.

Signed-off-by Bernhard Walle <[email protected]>
---
 Documentation/kdump/kdump.txt |   35 ++++++-----------------------------
 1 file changed, 6 insertions(+), 29 deletions(-)
Documentation/kdump/kdump.txt +6 -29
@@ -159,16 +159,17 @@ Dump-capture kernel config options (Arch
    CONFIG_PROC_VMCORE=y
    (CONFIG_PROC_VMCORE is set by default when CONFIG_CRASH_DUMP is selected.)
 
-Dump-capture kernel config options (Arch Dependent, i386)
---------------------------------------------------------
-1) On x86, enable high memory support under "Processor type and
+Dump-capture kernel config options (Arch Dependent, i386 and x86_64)
+--------------------------------------------------------------------
+
+1) On i386, enable high memory support under "Processor type and
    features":
 
    CONFIG_HIGHMEM64G=y
    or
    CONFIG_HIGHMEM4G
 
-2) On x86 and x86_64, disable symmetric multi-processing support
+2) On i386 and x86_64, disable symmetric multi-processing support
    under "Processor type and features":
 
    CONFIG_SMP=n

@@ -203,28 +204,6 @@ Dump-capture kernel config options (Arch
 5) Make and install the kernel and its modules. DO NOT add this kernel
    to the boot loader configuration files.
 
-Dump-capture kernel config options (Arch Dependent, x86_64)
-----------------------------------------------------------
-1) On x86 and x86_64, disable symmetric multi-processing support
-   under "Processor type and features":
-
-   CONFIG_SMP=n
-
-   (If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line
-   when loading the dump-capture kernel, see section "Load the Dump-capture
-   Kernel".)
-
-2) Use a suitable value for "Physical address where the kernel is
-   loaded" (under "Processor type and features"). This only appears when
-   "kernel crash dumps" is enabled. By default this value is 0x1000000
-   (16MB). It should be the same as X in the "crashkernel=Y@X" boot
-   parameter.
-
-   For x86_64, normally "CONFIG_PHYSICAL_START=0x1000000".
-
-3) Make and install the kernel and its modules. DO NOT add this kernel
-   to the boot loader configuration files.
-
 Dump-capture kernel config options (Arch Dependent, ppc64)
 ----------------------------------------------------------
 

@@ -282,11 +261,9 @@ Based on the architecture and type of im
 can choose to load the uncompressed vmlinux or compressed bzImage/vmlinuz
 of dump-capture kernel. Following is the summary.
 
-For i386:
+For i386 and x86_64:
 	- Use vmlinux if kernel is not relocatable.
 	- Use bzImage/vmlinuz if kernel is relocatable.
-For x86_64:
-	- Use vmlinux
 For ppc64:
 	- Use vmlinux
 For ia64:
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#2 lore raw

Re: [patch 1/3] Express relocatability of kernel on x86_64 in documentation

Quoted 6 lines · On Sun, 09 Sep 2007 10:06:21 +0200 Bernhard Walle wrote:

This patch adapts the Documentation/kdump/kdump.txt file to express the fact that the x86_64 kernel is now also relocatable. This makes i386 and x86_64 now behave the same, simplifying the documentation.

Signed-off-by Bernhard Walle <[email protected]>

Hi,
Can we also please reconcile the CRASH_DUMP Kconfig help text? I.e., it says

The crash dump kernel must be compiled
to a memory address not used by the main kernel or BIOS using PHYSICAL_START.

but this ignores the use of RELOCATABLE, right?

---
From: Randy Dunlap <[email protected]>

Update help text for CONFIG_CRASH_DUMP.
Fix typos in CONFIG_RELOCATABLE.
Use tab + 2 spaces for indentation on all lines.

Signed-off-by Randy Dunlap <[email protected]>
---
 arch/i386/Kconfig   |   17 +++++++++--------
 arch/x86_64/Kconfig |   21 +++++++++++----------
 2 files changed, 20 insertions(+), 18 deletions(-)
arch/i386/Kconfig +9 -8
@@ -820,12 +820,13 @@ config CRASH_DUMP
 	depends on HIGHMEM
 	help
 	  Generate crash dump after being started by kexec.
-          This should be normally only set in special crash dump kernels
+	  This should be normally only set in special crash dump kernels
 	  which are loaded in the main kernel with kexec-tools into
 	  a specially reserved region and then later executed after
 	  a crash by kdump/kexec. The crash dump kernel must be compiled
-          to a memory address not used by the main kernel or BIOS using
-          PHYSICAL_START.
+	  to a memory address not used by the main kernel or BIOS using
+	  PHYSICAL_START, or it must be built as a relocatable image
+	  (CONFIG_RELOCATABLE=y).
 	  For more details see Documentation/kdump/kdump.txt
 
 config PHYSICAL_START

@@ -871,17 +872,17 @@ config PHYSICAL_START
 	  Don't change this unless you know what you are doing.
 
 config RELOCATABLE
-	bool "Build a relocatable kernel(EXPERIMENTAL)"
+	bool "Build a relocatable kernel (EXPERIMENTAL)"
 	depends on EXPERIMENTAL
 	help
 	  This builds a kernel image that retains relocation information
-          so it can be loaded someplace besides the default 1MB.
+	  so it can be loaded someplace besides the default 1MB.
 	  The relocations tend to make the kernel binary about 10% larger,
-          but are discarded at runtime.
+	  but are discarded at runtime.
 
 	  One use is for the kexec on panic case where the recovery kernel
-          must live at a different physical address than the primary
-          kernel.
+	  must live at a different physical address than the primary
+	  kernel.
 
 config PHYSICAL_ALIGN
 	hex "Alignment value to which kernel should be aligned"
arch/x86_64/Kconfig +11 -10
@@ -575,17 +575,18 @@ config CRASH_DUMP
 	bool "kernel crash dumps (EXPERIMENTAL)"
 	depends on EXPERIMENTAL
 	help
-          Generate crash dump after being started by kexec.
-          This should be normally only set in special crash dump kernels
-          which are loaded in the main kernel with kexec-tools into
-          a specially reserved region and then later executed after
-          a crash by kdump/kexec. The crash dump kernel must be compiled
+	  Generate crash dump after being started by kexec.
+	  This should be normally only set in special crash dump kernels
+	  which are loaded in the main kernel with kexec-tools into
+	  a specially reserved region and then later executed after
+	  a crash by kdump/kexec. The crash dump kernel must be compiled
 	  to a memory address not used by the main kernel or BIOS using
-	  PHYSICAL_START.
-          For more details see Documentation/kdump/kdump.txt
+	  PHYSICAL_START, or it must be built as a relocatable image
+	  (CONFIG_RELOCATABLE=y).
+	  For more details see Documentation/kdump/kdump.txt
 
 config RELOCATABLE
-	bool "Build a relocatable kernel(EXPERIMENTAL)"
+	bool "Build a relocatable kernel (EXPERIMENTAL)"
 	depends on EXPERIMENTAL
 	help
 	  Builds a relocatable kernel. This enables loading and running

@@ -596,8 +597,8 @@ config RELOCATABLE
 	  must live at a different physical address than the primary
 	  kernel.
 
-	  Note: If CONFIG_RELOCATABLE=y, then kernel run from the address
-	  it has been loaded at and compile time physical address
+	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
+	  it has been loaded at and the compile time physical address
 	  (CONFIG_PHYSICAL_START) is ignored.
 
 config PHYSICAL_START

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#3 lore raw

PATCH 2/3 Express new ELF32 mechanisms in documentation

In reply to Bernhard Walle

This patch reflects the
http://git.kernel.org/?p=linux/kernel/git/horms/kexec-tools-testing.git;a=commit;h=b9c3648e690ad0dad12389659673206213a09760
change in kexec-tools-testing also now in the kernel documentation.

Signed-off-by Bernhard Walle <[email protected]>
---
 Documentation/kdump/kdump.txt |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)
Documentation/kdump/kdump.txt +7 -5
@@ -301,11 +301,13 @@ For ppc64:
 Notes on loading the dump-capture kernel:
 
 * By default, the ELF headers are stored in ELF64 format to support
-  systems with more than 4GB memory. The --elf32-core-headers option can
-  be used to force the generation of ELF32 headers. This is necessary
-  because GDB currently cannot open vmcore files with ELF64 headers on
-  32-bit systems. ELF32 headers can be used on non-PAE systems (that is,
-  less than 4GB of memory).
+  systems with more than 4GB memory. On i386, kexec automatically checks if
+  the physical RAM size exceeds the 4 GB limit and if not, uses ELF32.
+  So, on non-PAE systems, ELF32 is always used.
+
+  The --elf32-core-headers option can be used to force the generation of ELF32
+  headers. This is necessary because GDB currently cannot open vmcore files
+  with ELF64 headers on 32-bit systems.
 
 * The "irqpoll" boot parameter reduces driver initialization failures
   due to shared interrupts in the dump-capture kernel.
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PATCH 3/3 Add reset_devices to the recommended parameters

In reply to Bernhard Walle

This patch adds the "reset_devices" option (that's used only by one device driver for now) to the recommended list of command line parameters for kdump.

Meaning (Documentation/kernel-parameters.txt):
reset_devices [KNL] Force drivers to reset the underlying device
during initialization.

Signed-off-by Bernhard Walle <[email protected]>
---
 Documentation/kdump/kdump.txt |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
Documentation/kdump/kdump.txt +2 -2
@@ -292,10 +292,10 @@ Following are the arch specific command 
 loading dump-capture kernel.
 
 For i386, x86_64 and ia64:
-	"1 irqpoll maxcpus=1"
+	"1 irqpoll maxcpus=1 reset_devices"
 
 For ppc64:
-	"1 maxcpus=1 noirqdistrib"
+	"1 maxcpus=1 noirqdistrib reset_devices"
 
 
 Notes on loading the dump-capture kernel:
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