x86 idle cruft removal

PATCH In review Len Brown 13 participants 143 messages Mar 24, 2011 – Jul 15, 2011

Subsystems (11)

Documentation Arm (32-bit) x86 Block layer +7 more subsystems

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Len Brown

author reviewer

2011-03-24 07:08 UTC #0 lore raw

cover x86 idle cruft removal

A bit of Spring-cleaning in the x86 idle code,
so that we don't need to maintain this baggage
through upcoming cpuidle changes.

cheers,
-Len

Len Brown

author reviewer

2011-03-24 07:08 UTC #1 lore raw

PATCH 1/5 x86 idle: remove "no-hlt" cmdline param

From: Len Brown <[email protected]>

The X86_32-only "no-hlt" option was the functional equivalent of "idle=poll" for the idle loop.

It would also set the X86_32-only "hlt_bug" line in the /proc/cpuinfo, and cause halt to be skipped in stop_this_cpu().

Signed-off-by Len Brown <[email protected]>

---
 Documentation/kernel-parameters.txt |    4 ----
 arch/x86/kernel/cpu/bugs.c          |    8 --------
 2 files changed, 0 insertions(+), 12 deletions(-)

Documentation/kernel-parameters.txt +0 -4

index f4a04c0..e6b4843 100644
@@ -1666,10 +1666,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			wfi(ARM) instruction doesn't work correctly and not to
 			use it. This is also useful when using JTAG debugger.
 
-	no-hlt		[BUGS=X86-32] Tells the kernel that the hlt
-			instruction doesn't work correctly and not to
-			use it.
-
 	no_file_caps	Tells the kernel not to honor file capabilities.  The
 			only way then for a file to be executed with privilege
 			is to be setuid root or executed by root.

arch/x86/kernel/cpu/bugs.c +0 -8

index c39576c..4c91631 100644
@@ -17,14 +17,6 @@
 #include <asm/paravirt.h>
 #include <asm/alternative.h>
 
-static int __init no_halt(char *s)
-{
-	boot_cpu_data.hlt_works_ok = 0;
-	return 1;
-}
-
-__setup("no-hlt", no_halt);
-
 static int __init no_387(char *s)
 {
 	boot_cpu_data.hard_math = 0;

Signature · 1 line

1.7.4.1.343.ga91df

Len Brown

author reviewer

2011-03-24 07:09 UTC #2 lore raw

PATCH 1/5 x86 idle: remove "no-hlt" cmdline param

In reply to Len Brown

From: Len Brown <[email protected]>

The X86_32-only "no-hlt" option was the functional equivalent of "idle=poll" for the idle loop.

It would also set the X86_32-only "hlt_bug" line in the /proc/cpuinfo, and cause halt to be skipped in stop_this_cpu().

Signed-off-by Len Brown <[email protected]>

---
 Documentation/kernel-parameters.txt |    4 ----
 arch/x86/kernel/cpu/bugs.c          |    8 --------
 2 files changed, 0 insertions(+), 12 deletions(-)

Documentation/kernel-parameters.txt +0 -4

index f4a04c0..e6b4843 100644
@@ -1666,10 +1666,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			wfi(ARM) instruction doesn't work correctly and not to
 			use it. This is also useful when using JTAG debugger.
 
-	no-hlt		[BUGS=X86-32] Tells the kernel that the hlt
-			instruction doesn't work correctly and not to
-			use it.
-
 	no_file_caps	Tells the kernel not to honor file capabilities.  The
 			only way then for a file to be executed with privilege
 			is to be setuid root or executed by root.

arch/x86/kernel/cpu/bugs.c +0 -8

index c39576c..4c91631 100644
@@ -17,14 +17,6 @@
 #include <asm/paravirt.h>
 #include <asm/alternative.h>
 
-static int __init no_halt(char *s)
-{
-	boot_cpu_data.hlt_works_ok = 0;
-	return 1;
-}
-
-__setup("no-hlt", no_halt);
-
 static int __init no_387(char *s)
 {
 	boot_cpu_data.hard_math = 0;

Signature · 1 line

1.7.4.1.343.ga91df

Len Brown

author reviewer

2011-03-24 07:08 UTC #3 lore raw

PATCH 2/5 x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Len Brown

From: Len Brown <[email protected]>

hlt_works_ok was X86_32 only, initialized to 1, and never cleared.

On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no"

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |    5 -----
 arch/x86/kernel/cpu/bugs.c       |    5 +----
 arch/x86/kernel/cpu/proc.c       |    2 --
 arch/x86/kernel/process.c        |    2 +-
 arch/x86/kernel/setup.c          |    4 ++--
 arch/x86/xen/setup.c             |    3 ---
 6 files changed, 4 insertions(+), 17 deletions(-)

arch/x86/include/asm/processor.h +0 -5

index 45636ce..b5c83f1 100644
@@ -67,7 +67,6 @@ struct cpuinfo_x86 {
 	char			wp_works_ok;	/* It doesn't on 386's */
 
 	/* Problems on some 486Dx4's and old 386's: */
-	char			hlt_works_ok;
 	char			hard_math;
 	char			rfu;
 	char			fdiv_bug;

@@ -150,11 +149,7 @@ extern const struct seq_operations cpuinfo_op;
 
 static inline int hlt_works(int cpu)
 {
-#ifdef CONFIG_X86_32
-	return cpu_data(cpu).hlt_works_ok;
-#else
 	return 1;
-#endif
 }
 
 #define cache_line_size()	(boot_cpu_data.x86_cache_alignment)

arch/x86/kernel/cpu/bugs.c +1 -4

index 4c91631..b5e2910 100644
@@ -82,10 +82,7 @@ static void __init check_hlt(void)
 		return;
 
 	printk(KERN_INFO "Checking 'hlt' instruction... ");
-	if (!boot_cpu_data.hlt_works_ok) {
-		printk("disabled\n");
-		return;
-	}
+
 	halt();
 	halt();
 	halt();

arch/x86/kernel/cpu/proc.c +0 -2

index 62ac8cb..203feb7 100644
@@ -33,7 +33,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 	int fpu_exception = c->hard_math && (ignore_fpu_irq || cpu_has_fpu);
 	seq_printf(m,
 		   "fdiv_bug\t: %s\n"
-		   "hlt_bug\t\t: %s\n"
 		   "f00f_bug\t: %s\n"
 		   "coma_bug\t: %s\n"
 		   "fpu\t\t: %s\n"

@@ -41,7 +40,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 		   "cpuid level\t: %d\n"
 		   "wp\t\t: %s\n",
 		   c->fdiv_bug ? "yes" : "no",
-		   c->hlt_works_ok ? "no" : "yes",
 		   c->f00f_bug ? "yes" : "no",
 		   c->coma_bug ? "yes" : "no",
 		   c->hard_math ? "yes" : "no",

arch/x86/kernel/process.c +1 -1

index ff45541..4966c7e 100644
@@ -362,7 +362,7 @@ EXPORT_SYMBOL(enable_hlt);
 
 static inline int hlt_use_halt(void)
 {
-	return (!hlt_counter && boot_cpu_data.hlt_works_ok);
+	return (!hlt_counter);
 }
 #else
 static inline int hlt_use_halt(void)

arch/x86/kernel/setup.c +2 -2

index d3cfe26..fab5631 100644
@@ -175,9 +175,9 @@ static struct resource bss_resource = {
 
 #ifdef CONFIG_X86_32
 /* cpu data as detected by the assembly code in head.S */
-struct cpuinfo_x86 new_cpu_data __cpuinitdata = {0, 0, 0, 0, -1, 1, 0, 0, -1};
+struct cpuinfo_x86 new_cpu_data __cpuinitdata = {0, 0, 0, 0, -1, 0, 0, -1};
 /* common cpu data for all cpus */
-struct cpuinfo_x86 boot_cpu_data __read_mostly = {0, 0, 0, 0, -1, 1, 0, 0, -1};
+struct cpuinfo_x86 boot_cpu_data __read_mostly = {0, 0, 0, 0, -1, 0, 0, -1};
 EXPORT_SYMBOL(boot_cpu_data);
 static void set_mca_bus(int x)
 {

arch/x86/xen/setup.c +0 -3

index a8a66a5..97d2fbd 100644
@@ -351,9 +351,6 @@ void __init xen_arch_setup(void)
 	       COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);
 
 	/* Set up idle, making sure it calls safe_halt() pvop */
-#ifdef CONFIG_X86_32
-	boot_cpu_data.hlt_works_ok = 1;
-#endif
 	pm_idle = default_idle;
 	boot_option_idle_override = IDLE_HALT;

Signature · 1 line

1.7.4.1.343.ga91df

Len Brown

author reviewer

2011-03-24 07:09 UTC #4 lore raw

PATCH 2/5 x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Len Brown

From: Len Brown <[email protected]>

hlt_works_ok was X86_32 only, initialized to 1, and never cleared.

On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no"

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |    5 -----
 arch/x86/kernel/cpu/bugs.c       |    5 +----
 arch/x86/kernel/cpu/proc.c       |    2 --
 arch/x86/kernel/process.c        |    2 +-
 arch/x86/kernel/setup.c          |    4 ++--
 arch/x86/xen/setup.c             |    3 ---
 6 files changed, 4 insertions(+), 17 deletions(-)

arch/x86/include/asm/processor.h +0 -5

index 45636ce..b5c83f1 100644
@@ -67,7 +67,6 @@ struct cpuinfo_x86 {
 	char			wp_works_ok;	/* It doesn't on 386's */
 
 	/* Problems on some 486Dx4's and old 386's: */
-	char			hlt_works_ok;
 	char			hard_math;
 	char			rfu;
 	char			fdiv_bug;

@@ -150,11 +149,7 @@ extern const struct seq_operations cpuinfo_op;
 
 static inline int hlt_works(int cpu)
 {
-#ifdef CONFIG_X86_32
-	return cpu_data(cpu).hlt_works_ok;
-#else
 	return 1;
-#endif
 }
 
 #define cache_line_size()	(boot_cpu_data.x86_cache_alignment)

arch/x86/kernel/cpu/bugs.c +1 -4

index 4c91631..b5e2910 100644
@@ -82,10 +82,7 @@ static void __init check_hlt(void)
 		return;
 
 	printk(KERN_INFO "Checking 'hlt' instruction... ");
-	if (!boot_cpu_data.hlt_works_ok) {
-		printk("disabled\n");
-		return;
-	}
+
 	halt();
 	halt();
 	halt();

arch/x86/kernel/cpu/proc.c +0 -2

index 62ac8cb..203feb7 100644
@@ -33,7 +33,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 	int fpu_exception = c->hard_math && (ignore_fpu_irq || cpu_has_fpu);
 	seq_printf(m,
 		   "fdiv_bug\t: %s\n"
-		   "hlt_bug\t\t: %s\n"
 		   "f00f_bug\t: %s\n"
 		   "coma_bug\t: %s\n"
 		   "fpu\t\t: %s\n"

@@ -41,7 +40,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 		   "cpuid level\t: %d\n"
 		   "wp\t\t: %s\n",
 		   c->fdiv_bug ? "yes" : "no",
-		   c->hlt_works_ok ? "no" : "yes",
 		   c->f00f_bug ? "yes" : "no",
 		   c->coma_bug ? "yes" : "no",
 		   c->hard_math ? "yes" : "no",

arch/x86/kernel/process.c +1 -1

index ff45541..4966c7e 100644
@@ -362,7 +362,7 @@ EXPORT_SYMBOL(enable_hlt);
 
 static inline int hlt_use_halt(void)
 {
-	return (!hlt_counter && boot_cpu_data.hlt_works_ok);
+	return (!hlt_counter);
 }
 #else
 static inline int hlt_use_halt(void)

arch/x86/kernel/setup.c +2 -2

index d3cfe26..fab5631 100644
@@ -175,9 +175,9 @@ static struct resource bss_resource = {
 
 #ifdef CONFIG_X86_32
 /* cpu data as detected by the assembly code in head.S */
-struct cpuinfo_x86 new_cpu_data __cpuinitdata = {0, 0, 0, 0, -1, 1, 0, 0, -1};
+struct cpuinfo_x86 new_cpu_data __cpuinitdata = {0, 0, 0, 0, -1, 0, 0, -1};
 /* common cpu data for all cpus */
-struct cpuinfo_x86 boot_cpu_data __read_mostly = {0, 0, 0, 0, -1, 1, 0, 0, -1};
+struct cpuinfo_x86 boot_cpu_data __read_mostly = {0, 0, 0, 0, -1, 0, 0, -1};
 EXPORT_SYMBOL(boot_cpu_data);
 static void set_mca_bus(int x)
 {

arch/x86/xen/setup.c +0 -3

index a8a66a5..97d2fbd 100644
@@ -351,9 +351,6 @@ void __init xen_arch_setup(void)
 	       COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);
 
 	/* Set up idle, making sure it calls safe_halt() pvop */
-#ifdef CONFIG_X86_32
-	boot_cpu_data.hlt_works_ok = 1;
-#endif
 	pm_idle = default_idle;
 	boot_option_idle_override = IDLE_HALT;

Signature · 1 line

1.7.4.1.343.ga91df

Len Brown

author reviewer

2011-03-24 07:08 UTC #5 lore raw

PATCH 3/5 x86 idle: remove NOP halt_works()

In reply to Len Brown

From: Len Brown <[email protected]>

no functional change

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |    5 -----
 arch/x86/kernel/process.c        |    3 +--
 2 files changed, 1 insertions(+), 7 deletions(-)

arch/x86/include/asm/processor.h +0 -5

index b5c83f1..8776232 100644
@@ -147,11 +147,6 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
 
 extern const struct seq_operations cpuinfo_op;
 
-static inline int hlt_works(int cpu)
-{
-	return 1;
-}
-
 #define cache_line_size()	(boot_cpu_data.x86_cache_alignment)
 
 extern void cpu_detect(struct cpuinfo_x86 *c);

arch/x86/kernel/process.c +1 -2

index 4966c7e..cd461c3 100644
@@ -414,8 +414,7 @@ void stop_this_cpu(void *dummy)
 	disable_local_APIC();
 
 	for (;;) {
-		if (hlt_works(smp_processor_id()))
-			halt();
+		halt();
 	}
 }

Signature · 1 line

1.7.4.1.343.ga91df

Len Brown

author reviewer

2011-03-24 07:08 UTC #6 lore raw

PATCH 3/5 x86 idle: remove NOP halt_works()

In reply to Len Brown

From: Len Brown <[email protected]>

no functional change

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |    5 -----
 arch/x86/kernel/process.c        |    3 +--
 2 files changed, 1 insertions(+), 7 deletions(-)

arch/x86/include/asm/processor.h +0 -5

index b5c83f1..8776232 100644
@@ -147,11 +147,6 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
 
 extern const struct seq_operations cpuinfo_op;
 
-static inline int hlt_works(int cpu)
-{
-	return 1;
-}
-
 #define cache_line_size()	(boot_cpu_data.x86_cache_alignment)
 
 extern void cpu_detect(struct cpuinfo_x86 *c);

arch/x86/kernel/process.c +1 -2

index 4966c7e..cd461c3 100644
@@ -414,8 +414,7 @@ void stop_this_cpu(void *dummy)
 	disable_local_APIC();
 
 	for (;;) {
-		if (hlt_works(smp_processor_id()))
-			halt();
+		halt();
 	}
 }

Signature · 1 line

1.7.4.1.343.ga91df

Len Brown

author reviewer

2011-03-24 07:08 UTC #7 lore raw

PATCH 4/5 x86 idle floppy: delete disable_hlt()/enable_hlt()

In reply to Len Brown

From: Len Brown <[email protected]>

The X86_32-only disable_hlt/enable_hlt mechanism was used by the 32-bit floppy driver. Its effect was to replace the use of the HLT instruction inside default_idle() with cpu_relax().

Unlcear why this workaround was ever needed, it was commented:

floppy.c said:

"disable hlt during certain critical i/o operations"

x86/kernel/process.c said:

"This halt magic was a workaround for ancient floppy DMA
wreckage. It should be safe to remove."

So remove it, as it allows us to simplify the x86 idle code.

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/system.h |    7 -------
 arch/x86/kernel/process.c     |   24 ------------------------
 drivers/block/floppy.c        |   35 -----------------------------------
 3 files changed, 0 insertions(+), 66 deletions(-)

arch/x86/include/asm/system.h +0 -7

index 33ecc3e..013dd42 100644
@@ -93,10 +93,6 @@ do {									\
 			"memory");					\
 } while (0)
 
-/*
- * disable hlt during certain critical i/o operations
- */
-#define HAVE_DISABLE_HLT
 #else
 #define __SAVE(reg, offset) "movq %%" #reg ",(14-" #offset ")*8(%%rsp)\n\t"
 #define __RESTORE(reg, offset) "movq (14-" #offset ")*8(%%rsp),%%" #reg "\n\t"

@@ -337,9 +333,6 @@ static inline void clflush(volatile void *__p)
 
 #define nop() asm volatile ("nop")
 
-void disable_hlt(void);
-void enable_hlt(void);
-
 void cpu_idle_wait(void);
 
 extern unsigned long arch_align_stack(unsigned long sp);

arch/x86/kernel/process.c +0 ~~-24~~

index cd461c3..8688ade 100644
@@ -342,34 +342,10 @@ EXPORT_SYMBOL(boot_option_idle_override);
 void (*pm_idle)(void);
 EXPORT_SYMBOL(pm_idle);
 
-#ifdef CONFIG_X86_32
-/*
- * This halt magic was a workaround for ancient floppy DMA
- * wreckage. It should be safe to remove.
- */
-static int hlt_counter;
-void disable_hlt(void)
-{
-	hlt_counter++;
-}
-EXPORT_SYMBOL(disable_hlt);
-
-void enable_hlt(void)
-{
-	hlt_counter--;
-}
-EXPORT_SYMBOL(enable_hlt);
-
-static inline int hlt_use_halt(void)
-{
-	return (!hlt_counter);
-}
-#else
 static inline int hlt_use_halt(void)
 {
 	return 1;
 }
-#endif
 
 /*
  * We use this if we don't have any better

drivers/block/floppy.c +0 ~~-35~~

index 77fc76f..9a4e006 100644
@@ -1032,36 +1032,6 @@ static int fd_wait_for_completion(unsigned long delay, timeout_fn function)
 	return 0;
 }
 
-static DEFINE_SPINLOCK(floppy_hlt_lock);
-static int hlt_disabled;
-static void floppy_disable_hlt(void)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&floppy_hlt_lock, flags);
-	if (!hlt_disabled) {
-		hlt_disabled = 1;
-#ifdef HAVE_DISABLE_HLT
-		disable_hlt();
-#endif
-	}
-	spin_unlock_irqrestore(&floppy_hlt_lock, flags);
-}
-
-static void floppy_enable_hlt(void)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&floppy_hlt_lock, flags);
-	if (hlt_disabled) {
-		hlt_disabled = 0;
-#ifdef HAVE_DISABLE_HLT
-		enable_hlt();
-#endif
-	}
-	spin_unlock_irqrestore(&floppy_hlt_lock, flags);
-}
-
 static void setup_DMA(void)
 {
 	unsigned long f;

@@ -1106,7 +1076,6 @@ static void setup_DMA(void)
 	fd_enable_dma();
 	release_dma_lock(f);
 #endif
-	floppy_disable_hlt();
 }
 
 static void show_floppy(void);

@@ -1708,7 +1677,6 @@ irqreturn_t floppy_interrupt(int irq, void *dev_id)
 	fd_disable_dma();
 	release_dma_lock(f);
 
-	floppy_enable_hlt();
 	do_floppy = NULL;
 	if (fdc >= N_FDC || FDCS->address == -1) {
 		/* we don't even know which FDC is the culprit */

@@ -1857,8 +1825,6 @@ static void floppy_shutdown(unsigned long data)
 		show_floppy();
 	cancel_activity();
 
-	floppy_enable_hlt();
-
 	flags = claim_dma_lock();
 	fd_disable_dma();
 	release_dma_lock(flags);

@@ -4503,7 +4469,6 @@ static void floppy_release_irq_and_dma(void)
 #if N_FDC > 1
 	set_dor(1, ~8, 0);
 #endif
-	floppy_enable_hlt();
 
 	if (floppy_track_buffer && max_buffer_sectors) {
 		tmpsize = max_buffer_sectors * 1024;

Signature · 1 line

1.7.4.1.343.ga91df

Len Brown

author reviewer

2011-03-24 07:08 UTC #8 lore raw

PATCH 4/5 x86 idle floppy: delete disable_hlt()/enable_hlt()

In reply to Len Brown

From: Len Brown <[email protected]>

The X86_32-only disable_hlt/enable_hlt mechanism was used by the 32-bit floppy driver. Its effect was to replace the use of the HLT instruction inside default_idle() with cpu_relax().

Unlcear why this workaround was ever needed, it was commented:

floppy.c said:

"disable hlt during certain critical i/o operations"

x86/kernel/process.c said:

"This halt magic was a workaround for ancient floppy DMA
wreckage. It should be safe to remove."

So remove it, as it allows us to simplify the x86 idle code.

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/system.h |    7 -------
 arch/x86/kernel/process.c     |   24 ------------------------
 drivers/block/floppy.c        |   35 -----------------------------------
 3 files changed, 0 insertions(+), 66 deletions(-)

arch/x86/include/asm/system.h +0 -7

index 33ecc3e..013dd42 100644
@@ -93,10 +93,6 @@ do {									\
 			"memory");					\
 } while (0)
 
-/*
- * disable hlt during certain critical i/o operations
- */
-#define HAVE_DISABLE_HLT
 #else
 #define __SAVE(reg, offset) "movq %%" #reg ",(14-" #offset ")*8(%%rsp)\n\t"
 #define __RESTORE(reg, offset) "movq (14-" #offset ")*8(%%rsp),%%" #reg "\n\t"

@@ -337,9 +333,6 @@ static inline void clflush(volatile void *__p)
 
 #define nop() asm volatile ("nop")
 
-void disable_hlt(void);
-void enable_hlt(void);
-
 void cpu_idle_wait(void);
 
 extern unsigned long arch_align_stack(unsigned long sp);

arch/x86/kernel/process.c +0 ~~-24~~

index cd461c3..8688ade 100644
@@ -342,34 +342,10 @@ EXPORT_SYMBOL(boot_option_idle_override);
 void (*pm_idle)(void);
 EXPORT_SYMBOL(pm_idle);
 
-#ifdef CONFIG_X86_32
-/*
- * This halt magic was a workaround for ancient floppy DMA
- * wreckage. It should be safe to remove.
- */
-static int hlt_counter;
-void disable_hlt(void)
-{
-	hlt_counter++;
-}
-EXPORT_SYMBOL(disable_hlt);
-
-void enable_hlt(void)
-{
-	hlt_counter--;
-}
-EXPORT_SYMBOL(enable_hlt);
-
-static inline int hlt_use_halt(void)
-{
-	return (!hlt_counter);
-}
-#else
 static inline int hlt_use_halt(void)
 {
 	return 1;
 }
-#endif
 
 /*
  * We use this if we don't have any better

drivers/block/floppy.c +0 ~~-35~~

index 77fc76f..9a4e006 100644
@@ -1032,36 +1032,6 @@ static int fd_wait_for_completion(unsigned long delay, timeout_fn function)
 	return 0;
 }
 
-static DEFINE_SPINLOCK(floppy_hlt_lock);
-static int hlt_disabled;
-static void floppy_disable_hlt(void)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&floppy_hlt_lock, flags);
-	if (!hlt_disabled) {
-		hlt_disabled = 1;
-#ifdef HAVE_DISABLE_HLT
-		disable_hlt();
-#endif
-	}
-	spin_unlock_irqrestore(&floppy_hlt_lock, flags);
-}
-
-static void floppy_enable_hlt(void)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&floppy_hlt_lock, flags);
-	if (hlt_disabled) {
-		hlt_disabled = 0;
-#ifdef HAVE_DISABLE_HLT
-		enable_hlt();
-#endif
-	}
-	spin_unlock_irqrestore(&floppy_hlt_lock, flags);
-}
-
 static void setup_DMA(void)
 {
 	unsigned long f;

@@ -1106,7 +1076,6 @@ static void setup_DMA(void)
 	fd_enable_dma();
 	release_dma_lock(f);
 #endif
-	floppy_disable_hlt();
 }
 
 static void show_floppy(void);

@@ -1708,7 +1677,6 @@ irqreturn_t floppy_interrupt(int irq, void *dev_id)
 	fd_disable_dma();
 	release_dma_lock(f);
 
-	floppy_enable_hlt();
 	do_floppy = NULL;
 	if (fdc >= N_FDC || FDCS->address == -1) {
 		/* we don't even know which FDC is the culprit */

@@ -1857,8 +1825,6 @@ static void floppy_shutdown(unsigned long data)
 		show_floppy();
 	cancel_activity();
 
-	floppy_enable_hlt();
-
 	flags = claim_dma_lock();
 	fd_disable_dma();
 	release_dma_lock(flags);

@@ -4503,7 +4469,6 @@ static void floppy_release_irq_and_dma(void)
 #if N_FDC > 1
 	set_dor(1, ~8, 0);
 #endif
-	floppy_enable_hlt();
 
 	if (floppy_track_buffer && max_buffer_sectors) {
 		tmpsize = max_buffer_sectors * 1024;

Signature · 1 line

1.7.4.1.343.ga91df

Andi Kleen

2011-03-24 15:58 UTC #9 lore raw

Re: [PATCH 4/5] x86 idle floppy: delete disable_hlt()/enable_hlt()

Quoted 9 lines · Len Brown

floppy.c said:
"disable hlt during certain critical i/o operations"
x86/kernel/process.c said:
"This halt magic was a workaround for ancient floppy DMA
wreckage. It should be safe to remove."

AFAIK it was used on some 386/486s. I suspect it's safe to remove now.

-Andi

Signature · 1 line

[email protected] -- Speaking for myself only

Len Brown

author reviewer

2011-03-24 07:08 UTC #10 lore raw

PATCH 5/5 x86 idle: remove NOP hlt_use_halt()

In reply to Len Brown

From: Len Brown <[email protected]>

hlt_use_halt() no longer has any effect, except to complicate the indentation in default_idle().

no functional change.

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/kernel/process.c |   39 ++++++++++++++-------------------------
 1 files changed, 14 insertions(+), 25 deletions(-)

arch/x86/kernel/process.c +14 ~~-25~~

index 8688ade..094d4ac 100644
@@ -342,39 +342,28 @@ EXPORT_SYMBOL(boot_option_idle_override);
 void (*pm_idle)(void);
 EXPORT_SYMBOL(pm_idle);
 
-static inline int hlt_use_halt(void)
-{
-	return 1;
-}
-
 /*
  * We use this if we don't have any better
  * idle routine..
  */
 void default_idle(void)
 {
-	if (hlt_use_halt()) {
-		trace_power_start(POWER_CSTATE, 1, smp_processor_id());
-		trace_cpu_idle(1, smp_processor_id());
-		current_thread_info()->status &= ~TS_POLLING;
-		/*
-		 * TS_POLLING-cleared state must be visible before we
-		 * test NEED_RESCHED:
-		 */
-		smp_mb();
+	trace_power_start(POWER_CSTATE, 1, smp_processor_id());
+	trace_cpu_idle(1, smp_processor_id());
+	current_thread_info()->status &= ~TS_POLLING;
+	/*
+	 * TS_POLLING-cleared state must be visible before we
+	 * test NEED_RESCHED:
+	 */
+	smp_mb();
 
-		if (!need_resched())
-			safe_halt();	/* enables interrupts racelessly */
-		else
-			local_irq_enable();
-		current_thread_info()->status |= TS_POLLING;
-		trace_power_end(smp_processor_id());
-		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
-	} else {
+	if (!need_resched())
+		safe_halt();	/* enables interrupts racelessly */
+	else
 		local_irq_enable();
-		/* loop is done by the caller */
-		cpu_relax();
-	}
+	current_thread_info()->status |= TS_POLLING;
+	trace_power_end(smp_processor_id());
+	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
 }
 #ifdef CONFIG_APM_MODULE
 EXPORT_SYMBOL(default_idle);

Signature · 1 line

1.7.4.1.343.ga91df

Len Brown

author reviewer

2011-03-24 07:09 UTC #11 lore raw

PATCH 5/5 x86 idle: remove NOP hlt_use_halt()

In reply to Len Brown

From: Len Brown <[email protected]>

hlt_use_halt() no longer has any effect, except to complicate the indentation in default_idle().

no functional change.

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/kernel/process.c |   39 ++++++++++++++-------------------------
 1 files changed, 14 insertions(+), 25 deletions(-)

arch/x86/kernel/process.c +14 ~~-25~~

index 8688ade..094d4ac 100644
@@ -342,39 +342,28 @@ EXPORT_SYMBOL(boot_option_idle_override);
 void (*pm_idle)(void);
 EXPORT_SYMBOL(pm_idle);
 
-static inline int hlt_use_halt(void)
-{
-	return 1;
-}
-
 /*
  * We use this if we don't have any better
  * idle routine..
  */
 void default_idle(void)
 {
-	if (hlt_use_halt()) {
-		trace_power_start(POWER_CSTATE, 1, smp_processor_id());
-		trace_cpu_idle(1, smp_processor_id());
-		current_thread_info()->status &= ~TS_POLLING;
-		/*
-		 * TS_POLLING-cleared state must be visible before we
-		 * test NEED_RESCHED:
-		 */
-		smp_mb();
+	trace_power_start(POWER_CSTATE, 1, smp_processor_id());
+	trace_cpu_idle(1, smp_processor_id());
+	current_thread_info()->status &= ~TS_POLLING;
+	/*
+	 * TS_POLLING-cleared state must be visible before we
+	 * test NEED_RESCHED:
+	 */
+	smp_mb();
 
-		if (!need_resched())
-			safe_halt();	/* enables interrupts racelessly */
-		else
-			local_irq_enable();
-		current_thread_info()->status |= TS_POLLING;
-		trace_power_end(smp_processor_id());
-		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
-	} else {
+	if (!need_resched())
+		safe_halt();	/* enables interrupts racelessly */
+	else
 		local_irq_enable();
-		/* loop is done by the caller */
-		cpu_relax();
-	}
+	current_thread_info()->status |= TS_POLLING;
+	trace_power_end(smp_processor_id());
+	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
 }
 #ifdef CONFIG_APM_MODULE
 EXPORT_SYMBOL(default_idle);

Signature · 1 line

1.7.4.1.343.ga91df

Len Brown

author reviewer

2011-03-31 06:03 UTC #14 lore raw

cover x86 idle cruft removal - v2

In reply to Len Brown

unchanged:

[PATCH 1/9] x86 idle: remove "no-hlt" cmdline param [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag [PATCH 3/9] x86 idle: remove NOP halt_works()
[PATCH 4/9] x86 idle floppy: delete disable_hlt()/enable_hlt() [PATCH 5/9] x86 idle: remove NOP hlt_use_halt()

new:

[PATCH 6/9] x86 idle APM: delete apm_cpu_idle(), and its use of pm_idle [PATCH 7/9] x86 idle: do not EXPORT_SYMBOL pm_idle and default_idle [PATCH 8/9] x86 idle: move mwait_idle_with_hints() to where it is used [PATCH 9/9] x86 idle: delete mwait_idle()

 Documentation/kernel-parameters.txt |   11 +--
 arch/x86/Kconfig                    |   11 --
 arch/x86/include/asm/processor.h    |   14 +--
 arch/x86/include/asm/system.h       |    7 -
 arch/x86/kernel/acpi/cstate.c       |   24 ++++
 arch/x86/kernel/apm_32.c            |  232 -----------------------------------
 arch/x86/kernel/cpu/bugs.c          |   13 +--
 arch/x86/kernel/cpu/proc.c          |    2 -
 arch/x86/kernel/process.c           |  127 +++-----------------
 arch/x86/kernel/setup.c             |    4 +-
 arch/x86/xen/setup.c                |    3 -
 drivers/acpi/processor_idle.c       |    1 -
 drivers/block/floppy.c              |   35 ------
 13 files changed, 45 insertions(+), 439 deletions(-)

What is next:

handle c1e_idle() vs default_idle()
run-time check for AMD workaround enable as part of default_idle?
give xen_arch_setup default_idle() w/o having it touch pm_idle
perhaps it can simply set a flag to disable cpuidle...
which is what would run if the xen kernel were booted on raw iron. Or can we handle this
at compile time?
delete pm_idle
x86 will then use default_idle or cpuidle
allow cpuidle to use default_idle to handle the period
where it polls because cpus have not yet registered

Len Brown

author reviewer

2011-03-31 06:03 UTC #15 lore raw

cover x86 idle cruft removal - v2

In reply to Len Brown

unchanged:

new:

 Documentation/kernel-parameters.txt |   11 +--
 arch/x86/Kconfig                    |   11 --
 arch/x86/include/asm/processor.h    |   14 +--
 arch/x86/include/asm/system.h       |    7 -
 arch/x86/kernel/acpi/cstate.c       |   24 ++++
 arch/x86/kernel/apm_32.c            |  232 -----------------------------------
 arch/x86/kernel/cpu/bugs.c          |   13 +--
 arch/x86/kernel/cpu/proc.c          |    2 -
 arch/x86/kernel/process.c           |  127 +++-----------------
 arch/x86/kernel/setup.c             |    4 +-
 arch/x86/xen/setup.c                |    3 -
 drivers/acpi/processor_idle.c       |    1 -
 drivers/block/floppy.c              |   35 ------
 13 files changed, 45 insertions(+), 439 deletions(-)

What is next:

Len Brown

author reviewer

2011-03-31 06:03 UTC #16 lore raw

PATCH 1/9 x86 idle: remove "no-hlt" cmdline param

From: Len Brown <[email protected]>

The X86_32-only "no-hlt" option was the functional equivalent of "idle=poll" for the idle loop.

It would also set the X86_32-only "hlt_bug" line in the /proc/cpuinfo, and cause halt to be skipped in stop_this_cpu().

Signed-off-by Len Brown <[email protected]>

---
 Documentation/kernel-parameters.txt |    4 ----
 arch/x86/kernel/cpu/bugs.c          |    8 --------
 2 files changed, 0 insertions(+), 12 deletions(-)

Documentation/kernel-parameters.txt +0 -4

index f4a04c0..e6b4843 100644
@@ -1666,10 +1666,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			wfi(ARM) instruction doesn't work correctly and not to
 			use it. This is also useful when using JTAG debugger.
 
-	no-hlt		[BUGS=X86-32] Tells the kernel that the hlt
-			instruction doesn't work correctly and not to
-			use it.
-
 	no_file_caps	Tells the kernel not to honor file capabilities.  The
 			only way then for a file to be executed with privilege
 			is to be setuid root or executed by root.

arch/x86/kernel/cpu/bugs.c +0 -8

index c39576c..4c91631 100644
@@ -17,14 +17,6 @@
 #include <asm/paravirt.h>
 #include <asm/alternative.h>
 
-static int __init no_halt(char *s)
-{
-	boot_cpu_data.hlt_works_ok = 0;
-	return 1;
-}
-
-__setup("no-hlt", no_halt);
-
 static int __init no_387(char *s)
 {
 	boot_cpu_data.hard_math = 0;

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:03 UTC #17 lore raw

PATCH 1/9 x86 idle: remove "no-hlt" cmdline param

In reply to Len Brown

From: Len Brown <[email protected]>

The X86_32-only "no-hlt" option was the functional equivalent of "idle=poll" for the idle loop.

It would also set the X86_32-only "hlt_bug" line in the /proc/cpuinfo, and cause halt to be skipped in stop_this_cpu().

Signed-off-by Len Brown <[email protected]>

---
 Documentation/kernel-parameters.txt |    4 ----
 arch/x86/kernel/cpu/bugs.c          |    8 --------
 2 files changed, 0 insertions(+), 12 deletions(-)

Documentation/kernel-parameters.txt +0 -4

index f4a04c0..e6b4843 100644
@@ -1666,10 +1666,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			wfi(ARM) instruction doesn't work correctly and not to
 			use it. This is also useful when using JTAG debugger.
 
-	no-hlt		[BUGS=X86-32] Tells the kernel that the hlt
-			instruction doesn't work correctly and not to
-			use it.
-
 	no_file_caps	Tells the kernel not to honor file capabilities.  The
 			only way then for a file to be executed with privilege
 			is to be setuid root or executed by root.

arch/x86/kernel/cpu/bugs.c +0 -8

index c39576c..4c91631 100644
@@ -17,14 +17,6 @@
 #include <asm/paravirt.h>
 #include <asm/alternative.h>
 
-static int __init no_halt(char *s)
-{
-	boot_cpu_data.hlt_works_ok = 0;
-	return 1;
-}
-
-__setup("no-hlt", no_halt);
-
 static int __init no_387(char *s)
 {
 	boot_cpu_data.hard_math = 0;

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:03 UTC #18 lore raw

PATCH 2/9 x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Len Brown

From: Len Brown <[email protected]>

hlt_works_ok was X86_32 only, initialized to 1, and never cleared.

On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no"

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |    5 -----
 arch/x86/kernel/cpu/bugs.c       |    5 +----
 arch/x86/kernel/cpu/proc.c       |    2 --
 arch/x86/kernel/process.c        |    2 +-
 arch/x86/kernel/setup.c          |    4 ++--
 arch/x86/xen/setup.c             |    3 ---
 6 files changed, 4 insertions(+), 17 deletions(-)

arch/x86/include/asm/processor.h +0 -5

index 45636ce..b5c83f1 100644
@@ -67,7 +67,6 @@ struct cpuinfo_x86 {
 	char			wp_works_ok;	/* It doesn't on 386's */
 
 	/* Problems on some 486Dx4's and old 386's: */
-	char			hlt_works_ok;
 	char			hard_math;
 	char			rfu;
 	char			fdiv_bug;

@@ -150,11 +149,7 @@ extern const struct seq_operations cpuinfo_op;
 
 static inline int hlt_works(int cpu)
 {
-#ifdef CONFIG_X86_32
-	return cpu_data(cpu).hlt_works_ok;
-#else
 	return 1;
-#endif
 }
 
 #define cache_line_size()	(boot_cpu_data.x86_cache_alignment)

arch/x86/kernel/cpu/bugs.c +1 -4

index 4c91631..b5e2910 100644
@@ -82,10 +82,7 @@ static void __init check_hlt(void)
 		return;
 
 	printk(KERN_INFO "Checking 'hlt' instruction... ");
-	if (!boot_cpu_data.hlt_works_ok) {
-		printk("disabled\n");
-		return;
-	}
+
 	halt();
 	halt();
 	halt();

arch/x86/kernel/cpu/proc.c +0 -2

index 62ac8cb..203feb7 100644
@@ -33,7 +33,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 	int fpu_exception = c->hard_math && (ignore_fpu_irq || cpu_has_fpu);
 	seq_printf(m,
 		   "fdiv_bug\t: %s\n"
-		   "hlt_bug\t\t: %s\n"
 		   "f00f_bug\t: %s\n"
 		   "coma_bug\t: %s\n"
 		   "fpu\t\t: %s\n"

@@ -41,7 +40,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 		   "cpuid level\t: %d\n"
 		   "wp\t\t: %s\n",
 		   c->fdiv_bug ? "yes" : "no",
-		   c->hlt_works_ok ? "no" : "yes",
 		   c->f00f_bug ? "yes" : "no",
 		   c->coma_bug ? "yes" : "no",
 		   c->hard_math ? "yes" : "no",

arch/x86/kernel/process.c +1 -1

index ff45541..4966c7e 100644
@@ -362,7 +362,7 @@ EXPORT_SYMBOL(enable_hlt);
 
 static inline int hlt_use_halt(void)
 {
-	return (!hlt_counter && boot_cpu_data.hlt_works_ok);
+	return (!hlt_counter);
 }
 #else
 static inline int hlt_use_halt(void)

arch/x86/kernel/setup.c +2 -2

index d3cfe26..fab5631 100644
@@ -175,9 +175,9 @@ static struct resource bss_resource = {
 
 #ifdef CONFIG_X86_32
 /* cpu data as detected by the assembly code in head.S */
-struct cpuinfo_x86 new_cpu_data __cpuinitdata = {0, 0, 0, 0, -1, 1, 0, 0, -1};
+struct cpuinfo_x86 new_cpu_data __cpuinitdata = {0, 0, 0, 0, -1, 0, 0, -1};
 /* common cpu data for all cpus */
-struct cpuinfo_x86 boot_cpu_data __read_mostly = {0, 0, 0, 0, -1, 1, 0, 0, -1};
+struct cpuinfo_x86 boot_cpu_data __read_mostly = {0, 0, 0, 0, -1, 0, 0, -1};
 EXPORT_SYMBOL(boot_cpu_data);
 static void set_mca_bus(int x)
 {

arch/x86/xen/setup.c +0 -3

index a8a66a5..97d2fbd 100644
@@ -351,9 +351,6 @@ void __init xen_arch_setup(void)
 	       COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);
 
 	/* Set up idle, making sure it calls safe_halt() pvop */
-#ifdef CONFIG_X86_32
-	boot_cpu_data.hlt_works_ok = 1;
-#endif
 	pm_idle = default_idle;
 	boot_option_idle_override = IDLE_HALT;

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:03 UTC #19 lore raw

PATCH 2/9 x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Len Brown

From: Len Brown <[email protected]>

hlt_works_ok was X86_32 only, initialized to 1, and never cleared.

On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no"

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |    5 -----
 arch/x86/kernel/cpu/bugs.c       |    5 +----
 arch/x86/kernel/cpu/proc.c       |    2 --
 arch/x86/kernel/process.c        |    2 +-
 arch/x86/kernel/setup.c          |    4 ++--
 arch/x86/xen/setup.c             |    3 ---
 6 files changed, 4 insertions(+), 17 deletions(-)

arch/x86/include/asm/processor.h +0 -5

index 45636ce..b5c83f1 100644
@@ -67,7 +67,6 @@ struct cpuinfo_x86 {
 	char			wp_works_ok;	/* It doesn't on 386's */
 
 	/* Problems on some 486Dx4's and old 386's: */
-	char			hlt_works_ok;
 	char			hard_math;
 	char			rfu;
 	char			fdiv_bug;

@@ -150,11 +149,7 @@ extern const struct seq_operations cpuinfo_op;
 
 static inline int hlt_works(int cpu)
 {
-#ifdef CONFIG_X86_32
-	return cpu_data(cpu).hlt_works_ok;
-#else
 	return 1;
-#endif
 }
 
 #define cache_line_size()	(boot_cpu_data.x86_cache_alignment)

arch/x86/kernel/cpu/bugs.c +1 -4

index 4c91631..b5e2910 100644
@@ -82,10 +82,7 @@ static void __init check_hlt(void)
 		return;
 
 	printk(KERN_INFO "Checking 'hlt' instruction... ");
-	if (!boot_cpu_data.hlt_works_ok) {
-		printk("disabled\n");
-		return;
-	}
+
 	halt();
 	halt();
 	halt();

arch/x86/kernel/cpu/proc.c +0 -2

index 62ac8cb..203feb7 100644
@@ -33,7 +33,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 	int fpu_exception = c->hard_math && (ignore_fpu_irq || cpu_has_fpu);
 	seq_printf(m,
 		   "fdiv_bug\t: %s\n"
-		   "hlt_bug\t\t: %s\n"
 		   "f00f_bug\t: %s\n"
 		   "coma_bug\t: %s\n"
 		   "fpu\t\t: %s\n"

@@ -41,7 +40,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 		   "cpuid level\t: %d\n"
 		   "wp\t\t: %s\n",
 		   c->fdiv_bug ? "yes" : "no",
-		   c->hlt_works_ok ? "no" : "yes",
 		   c->f00f_bug ? "yes" : "no",
 		   c->coma_bug ? "yes" : "no",
 		   c->hard_math ? "yes" : "no",

arch/x86/kernel/process.c +1 -1

index ff45541..4966c7e 100644
@@ -362,7 +362,7 @@ EXPORT_SYMBOL(enable_hlt);
 
 static inline int hlt_use_halt(void)
 {
-	return (!hlt_counter && boot_cpu_data.hlt_works_ok);
+	return (!hlt_counter);
 }
 #else
 static inline int hlt_use_halt(void)

arch/x86/kernel/setup.c +2 -2

index d3cfe26..fab5631 100644
@@ -175,9 +175,9 @@ static struct resource bss_resource = {
 
 #ifdef CONFIG_X86_32
 /* cpu data as detected by the assembly code in head.S */
-struct cpuinfo_x86 new_cpu_data __cpuinitdata = {0, 0, 0, 0, -1, 1, 0, 0, -1};
+struct cpuinfo_x86 new_cpu_data __cpuinitdata = {0, 0, 0, 0, -1, 0, 0, -1};
 /* common cpu data for all cpus */
-struct cpuinfo_x86 boot_cpu_data __read_mostly = {0, 0, 0, 0, -1, 1, 0, 0, -1};
+struct cpuinfo_x86 boot_cpu_data __read_mostly = {0, 0, 0, 0, -1, 0, 0, -1};
 EXPORT_SYMBOL(boot_cpu_data);
 static void set_mca_bus(int x)
 {

arch/x86/xen/setup.c +0 -3

index a8a66a5..97d2fbd 100644
@@ -351,9 +351,6 @@ void __init xen_arch_setup(void)
 	       COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);
 
 	/* Set up idle, making sure it calls safe_halt() pvop */
-#ifdef CONFIG_X86_32
-	boot_cpu_data.hlt_works_ok = 1;
-#endif
 	pm_idle = default_idle;
 	boot_option_idle_override = IDLE_HALT;

Signature · 1 line

1.7.4.2.406.gbe91

Ingo Molnar

2011-03-31 06:12 UTC #20 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

Quoted 5 lines · Len Brown

From: Len Brown <[email protected]>
hlt_works_ok was X86_32 only, initialized to 1, and never cleared.
On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no"

I think you missed the valid usecase where an old CPU with broken halt is booted with the no-hlt boot parameter and does not want to crash in the HLT instruction.

That "no-hlt" boot parameter does:

  arch/x86/kernel/cpu/bugs.c:     boot_cpu_data.hlt_works_ok = 0;

We can restrict compatibility, but *please* lets do it *explicitly*, not under some 'remove unused code' pretense ...

Could you please list all CPU models that are affected?

Thanks,

Ingo

Ingo Molnar

2011-03-31 06:13 UTC #21 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Len Brown

Quoted 5 lines · Len Brown

From: Len Brown <[email protected]>
hlt_works_ok was X86_32 only, initialized to 1, and never cleared.
On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no"

I think you missed the valid usecase where an old CPU with broken halt is booted with the no-hlt boot parameter and does not want to crash in the HLT instruction.

That "no-hlt" boot parameter does:

  arch/x86/kernel/cpu/bugs.c:     boot_cpu_data.hlt_works_ok = 0;

We can restrict compatibility, but *please* lets do it *explicitly*, not under some 'remove unused code' pretense ...

Could you please list all CPU models that are affected?

Thanks,

Ingo

Len Brown

author reviewer

2011-03-31 07:02 UTC #22 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

Quoted 8 lines

Quoted 3 lines
hlt_works_ok was X86_32 only, initialized to 1, and never cleared.
On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no"
I think you missed the valid usecase where an old CPU with broken halt is booted with the no-hlt boot parameter and does not want to crash in the HLT instruction.

Quoted 8 lines

That "no-hlt" boot parameter does:
  arch/x86/kernel/cpu/bugs.c:     boot_cpu_data.hlt_works_ok = 0;
We can restrict compatibility, but *please* lets do it *explicitly*, not under some 'remove unused code' pretense ...
Could you please list all CPU models that are affected?

"no-hlt" existed only for 32-bit, and there were exactly zero automatic invocations of it.

"idle=poll" does the same thing -- sans change a line in /proc/cpuinfo.

Do we really need both?

thanks,
-Len

Len Brown

author reviewer

2011-03-31 07:02 UTC #23 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Ingo Molnar

Quoted 8 lines

Quoted 3 lines
hlt_works_ok was X86_32 only, initialized to 1, and never cleared.
On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no"
I think you missed the valid usecase where an old CPU with broken halt is booted with the no-hlt boot parameter and does not want to crash in the HLT instruction.

Quoted 8 lines

That "no-hlt" boot parameter does:
  arch/x86/kernel/cpu/bugs.c:     boot_cpu_data.hlt_works_ok = 0;
We can restrict compatibility, but *please* lets do it *explicitly*, not under some 'remove unused code' pretense ...
Could you please list all CPU models that are affected?

"no-hlt" existed only for 32-bit, and there were exactly zero automatic invocations of it.

"idle=poll" does the same thing -- sans change a line in /proc/cpuinfo.

Do we really need both?

thanks,
-Len

Ingo Molnar

2011-03-31 08:18 UTC #24 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

Quoted 12 lines · Len Brown

Quoted 12 lines
Quoted 3 lines
hlt_works_ok was X86_32 only, initialized to 1, and never cleared.
On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no"
I think you missed the valid usecase where an old CPU with broken halt is booted with the no-hlt boot parameter and does not want to crash in the HLT instruction.
That "no-hlt" boot parameter does:
  arch/x86/kernel/cpu/bugs.c:     boot_cpu_data.hlt_works_ok = 0;

Quoted 7 lines

Quoted 4 lines
We can restrict compatibility, but *please* lets do it *explicitly*, not under some 'remove unused code' pretense ...
Could you please list all CPU models that are affected?
"no-hlt" existed only for 32-bit, and there were exactly zero automatic invocations of it.

Do we know whether a distro adds this to the boot line? Do we know about users relying on it.

Quoted 2 lines

"idle=poll" does the same thing -- sans change a line in /proc/cpuinfo.

It also has an effect on halt/poweroff, right?

Quoted 1 line

Do we really need both?

Probably not, as i said i do not disagree - i just think it should be more explicit. Make it a: "users of CPU models X beware" commit title, not 'remove inactive code' ...

So please list the affected hardware and list the affected boot parameter explicitly, in a well-titled commit that phases out this (very likely unused) compatibility hack and *document* the idle=poll workaround for ancient hardware.

There's still i386DX CPUs being manufactured these days - a 20+ years old CPU design is surprisingly resilient to spurious patent claims, for obvious reasons.

Really, there's no need to do things by stealth. There's few things worse than doing the right thing for the wrong reason - it becomes a bad habit of subtly broken thinking quickly.

Thanks,

Ingo

Ingo Molnar

2011-03-31 08:18 UTC #25 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Len Brown

Quoted 12 lines · Len Brown

Quoted 12 lines
Quoted 3 lines
hlt_works_ok was X86_32 only, initialized to 1, and never cleared.
On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no"
I think you missed the valid usecase where an old CPU with broken halt is booted with the no-hlt boot parameter and does not want to crash in the HLT instruction.
That "no-hlt" boot parameter does:
  arch/x86/kernel/cpu/bugs.c:     boot_cpu_data.hlt_works_ok = 0;

Quoted 7 lines

Quoted 4 lines
We can restrict compatibility, but *please* lets do it *explicitly*, not under some 'remove unused code' pretense ...
Could you please list all CPU models that are affected?
"no-hlt" existed only for 32-bit, and there were exactly zero automatic invocations of it.

Do we know whether a distro adds this to the boot line? Do we know about users relying on it.

Quoted 2 lines

"idle=poll" does the same thing -- sans change a line in /proc/cpuinfo.

It also has an effect on halt/poweroff, right?

Quoted 1 line

Do we really need both?

Probably not, as i said i do not disagree - i just think it should be more explicit. Make it a: "users of CPU models X beware" commit title, not 'remove inactive code' ...

There's still i386DX CPUs being manufactured these days - a 20+ years old CPU design is surprisingly resilient to spurious patent claims, for obvious reasons.

Really, there's no need to do things by stealth. There's few things worse than doing the right thing for the wrong reason - it becomes a bad habit of subtly broken thinking quickly.

Thanks,

Ingo

Alan Cox

2011-03-31 09:23 UTC #26 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

Quoted 2 lines

Do we know whether a distro adds this to the boot line? Do we know about users relying on it.

I certainly had hardware that needed it. Don't any more but this is more trying to rip out stuff without letting nature take its course.

It's a trivial feature item.

Quoted 5 lines

Quoted 1 line
Do we really need both?
Probably not, as i said i do not disagree - i just think it should be more explicit. Make it a: "users of CPU models X beware" commit title, not 'remove inactive code' ...

Just make the one config variable respond to both boot configuration options. The parser is __init code anyway so discarded so the actual code cost of compatibility is exactly NIL.

Alan

Alan Cox

2011-03-31 09:26 UTC #27 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Ingo Molnar

Quoted 2 lines

Do we know whether a distro adds this to the boot line? Do we know about users relying on it.

I certainly had hardware that needed it. Don't any more but this is more trying to rip out stuff without letting nature take its course.

It's a trivial feature item.

Quoted 5 lines

Quoted 1 line
Do we really need both?
Probably not, as i said i do not disagree - i just think it should be more explicit. Make it a: "users of CPU models X beware" commit title, not 'remove inactive code' ...

Just make the one config variable respond to both boot configuration options. The parser is __init code anyway so discarded so the actual code cost of compatibility is exactly NIL.

Alan

Ingo Molnar

2011-03-31 09:27 UTC #28 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

Quoted 7 lines · Alan Cox

Quoted 2 lines
Do we know whether a distro adds this to the boot line? Do we know about users relying on it.
I certainly had hardware that needed it. Don't any more but this is more trying to rip out stuff without letting nature take its course.
It's a trivial feature item.

Yes.

Quoted 9 lines

Quoted 5 lines
Quoted 1 line
Do we really need both?
Probably not, as i said i do not disagree - i just think it should be more explicit. Make it a: "users of CPU models X beware" commit title, not 'remove inactive code' ...
Just make the one config variable respond to both boot configuration options. The parser is __init code anyway so discarded so the actual code cost of compatibility is exactly NIL.

Yeah, agreed.

Btw., we used to auto-detect broken HLT systems IIRC - but that got lost already. We should at least honor the boot parameter.

Thanks,

Ingo

Ingo Molnar

2011-03-31 09:27 UTC #29 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Alan Cox

Quoted 7 lines · Alan Cox

Quoted 2 lines
Do we know whether a distro adds this to the boot line? Do we know about users relying on it.
I certainly had hardware that needed it. Don't any more but this is more trying to rip out stuff without letting nature take its course.
It's a trivial feature item.

Yes.

Quoted 9 lines

Quoted 5 lines
Quoted 1 line
Do we really need both?
Probably not, as i said i do not disagree - i just think it should be more explicit. Make it a: "users of CPU models X beware" commit title, not 'remove inactive code' ...
Just make the one config variable respond to both boot configuration options. The parser is __init code anyway so discarded so the actual code cost of compatibility is exactly NIL.

Yeah, agreed.

Btw., we used to auto-detect broken HLT systems IIRC - but that got lost already. We should at least honor the boot parameter.

Thanks,

Ingo

Alan Cox

2011-03-31 09:33 UTC #30 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

Quoted 2 lines

Btw., we used to auto-detect broken HLT systems IIRC - but that got lost already. We should at least honor the boot parameter.

I don't believe we ever auto detected them or found a way to do so. That was why the HLT message was printed before hlt was executed.

Alan Cox

2011-03-31 09:36 UTC #31 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Ingo Molnar

Quoted 2 lines

Btw., we used to auto-detect broken HLT systems IIRC - but that got lost already. We should at least honor the boot parameter.

I don't believe we ever auto detected them or found a way to do so. That was why the HLT message was printed before hlt was executed.

Ingo Molnar

2011-03-31 09:35 UTC #32 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

Quoted 5 lines · Alan Cox

Quoted 2 lines
Btw., we used to auto-detect broken HLT systems IIRC - but that got lost already. We should at least honor the boot parameter.
I don't believe we ever auto detected them or found a way to do so. That was why the HLT message was printed before hlt was executed.

Yeah - the CPU hang was unrecoverably deep so no auto-detection was possible.

That's seriously ancient stuff - still, keeping the boot option around (<10 lines of code) does not hurt anyone.

Thanks,

Ingo

Ingo Molnar

2011-03-31 09:36 UTC #33 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Alan Cox

Quoted 5 lines · Alan Cox

Quoted 2 lines
Btw., we used to auto-detect broken HLT systems IIRC - but that got lost already. We should at least honor the boot parameter.
I don't believe we ever auto detected them or found a way to do so. That was why the HLT message was printed before hlt was executed.

Yeah - the CPU hang was unrecoverably deep so no auto-detection was possible.

That's seriously ancient stuff - still, keeping the boot option around (<10 lines of code) does not hurt anyone.

Thanks,

Ingo

H. Peter Anvin

reviewer

2011-03-31 14:19 UTC #34 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

Quoted 6 lines · Ingo Molnar

Quoted 3 lines · Alan Cox
Quoted 2 lines
Btw., we used to auto-detect broken HLT systems IIRC - but that got lost already. We should at least honor the boot parameter.

Quoted 8 lines

Quoted 2 lines
I don't believe we ever auto detected them or found a way to do so. That was why the HLT message was printed before hlt was executed.
Yeah - the CPU hang was unrecoverably deep so no auto-detection was possible.
That's seriously ancient stuff - still, keeping the boot option around (<10 lines of code) does not hurt anyone.

What it was was bad power supplies or low-capacitance, high-inductance power distribution that happened to work with MS-DOS which always burned the CPU at 100% and therefore left the power draw relatively consistent current. A proper OS putting the CPU in HLT produced a lot more high frequency noise on the power busses, with disastrous results without proper bypass.

-hpa

Signature · 2 lines

H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

H. Peter Anvin

reviewer

2011-03-31 14:20 UTC #35 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Ingo Molnar

Quoted 6 lines · Ingo Molnar

Quoted 3 lines · Alan Cox
Quoted 2 lines
Btw., we used to auto-detect broken HLT systems IIRC - but that got lost already. We should at least honor the boot parameter.

Quoted 8 lines

Quoted 2 lines
I don't believe we ever auto detected them or found a way to do so. That was why the HLT message was printed before hlt was executed.
Yeah - the CPU hang was unrecoverably deep so no auto-detection was possible.
That's seriously ancient stuff - still, keeping the boot option around (<10 lines of code) does not hurt anyone.

-hpa

Signature · 2 lines

H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

Alan Cox

2011-03-31 14:41 UTC #36 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

Quoted 16 lines · On Thu, 31 Mar 2011 07:19:50 -0700 "H. Peter Anvin" <[email protected]> wrote:

Quoted 6 lines · Ingo Molnar
Quoted 3 lines · Alan Cox
Quoted 2 lines
Btw., we used to auto-detect broken HLT systems IIRC - but that got lost already. We should at least honor the boot parameter.
Quoted 8 lines
Quoted 2 lines
I don't believe we ever auto detected them or found a way to do so. That was why the HLT message was printed before hlt was executed.
Yeah - the CPU hang was unrecoverably deep so no auto-detection was possible.
That's seriously ancient stuff - still, keeping the boot option around (<10 lines of code) does not hurt anyone.

Quoted 6 lines

What it was was bad power supplies or low-capacitance, high-inductance power distribution that happened to work with MS-DOS which always burned the CPU at 100% and therefore left the power draw relatively consistent current. A proper OS putting the CPU in HLT produced a lot more high frequency noise on the power busses, with disastrous results without proper bypass.

And also chipset errata in some cases - eg some revisions of the CS5510 hung the box solid if a CPU hlt occurred during an IDE transfer. I don't think any CS5510s are still around although I've had mail from someone with a CS5520 in use not that long ago so who knows!

The joy of ancient history.

Alan Cox

2011-03-31 14:41 UTC #37 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to H. Peter Anvin

Quoted 16 lines · On Thu, 31 Mar 2011 07:19:50 -0700 "H. Peter Anvin" <[email protected]> wrote:

Quoted 6 lines · Ingo Molnar
Quoted 3 lines · Alan Cox
Quoted 2 lines
Btw., we used to auto-detect broken HLT systems IIRC - but that got lost already. We should at least honor the boot parameter.
Quoted 8 lines
Quoted 2 lines
I don't believe we ever auto detected them or found a way to do so. That was why the HLT message was printed before hlt was executed.
Yeah - the CPU hang was unrecoverably deep so no auto-detection was possible.
That's seriously ancient stuff - still, keeping the boot option around (<10 lines of code) does not hurt anyone.

Quoted 6 lines

What it was was bad power supplies or low-capacitance, high-inductance power distribution that happened to work with MS-DOS which always burned the CPU at 100% and therefore left the power draw relatively consistent current. A proper OS putting the CPU in HLT produced a lot more high frequency noise on the power busses, with disastrous results without proper bypass.

The joy of ancient history.

H. Peter Anvin

reviewer

2011-03-31 15:09 UTC #38 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

Quoted 8 lines · Alan Cox

Quoted 7 lines
What it was was bad power supplies or low-capacitance, high-inductance power distribution that happened to work with MS-DOS which always burned the CPU at 100% and therefore left the power draw relatively consistent current. A proper OS putting the CPU in HLT produced a lot more high frequency noise on the power busses, with disastrous results without proper bypass.

Quoted 6 lines

And also chipset errata in some cases - eg some revisions of the CS5510 hung the box solid if a CPU hlt occurred during an IDE transfer. I don't think any CS5510s are still around although I've had mail from someone with a CS5520 in use not that long ago so who knows!
The joy of ancient history.

Ah, yes, I guess there was a special cycle on the bus which the chipset could misinterpret.

-hpa

Signature · 2 lines

H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

H. Peter Anvin

reviewer

2011-03-31 15:09 UTC #39 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Alan Cox

Quoted 8 lines · Alan Cox

Quoted 7 lines
What it was was bad power supplies or low-capacitance, high-inductance power distribution that happened to work with MS-DOS which always burned the CPU at 100% and therefore left the power draw relatively consistent current. A proper OS putting the CPU in HLT produced a lot more high frequency noise on the power busses, with disastrous results without proper bypass.

Quoted 6 lines

And also chipset errata in some cases - eg some revisions of the CS5510 hung the box solid if a CPU hlt occurred during an IDE transfer. I don't think any CS5510s are still around although I've had mail from someone with a CS5520 in use not that long ago so who knows!
The joy of ancient history.

Ah, yes, I guess there was a special cycle on the bus which the chipset could misinterpret.

-hpa

Signature · 2 lines

H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

Len Brown

author reviewer

2011-03-31 18:07 UTC #40 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Ingo Molnar

Quoted 15 lines

Quoted 15 lines
Quoted 15 lines
Quoted 3 lines
hlt_works_ok was X86_32 only, initialized to 1, and never cleared.
On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no"
I think you missed the valid usecase where an old CPU with broken halt is booted with the no-hlt boot parameter and does not want to crash in the HLT instruction.
That "no-hlt" boot parameter does:
  arch/x86/kernel/cpu/bugs.c:     boot_cpu_data.hlt_works_ok = 0;
We can restrict compatibility, but *please* lets do it *explicitly*, not under some 'remove unused code' pretense ...

Quoted 7 lines

Quoted 4 lines
Quoted 1 line
Could you please list all CPU models that are affected?
"no-hlt" existed only for 32-bit, and there were exactly zero automatic invocations of it.
Do we know whether a distro adds this to the boot line? Do we know about users relying on it.

Impossible to know.

Quoted 4 lines

Quoted 2 lines
"idle=poll" does the same thing -- sans change a line in /proc/cpuinfo.
It also has an effect on halt/poweroff, right?

Yes, if somebody invokes kernel_halt(), then it
uses stop_this_cpu(), which uses HLT unless this flag is cleared.

The functional change of deleting "no-hlt", which was the only way to clear this flag, was in the previous patch, and so I should have mentioned it here.

stop_this_cpu() is not in the poweroff path.

It is a different topic, but I'd be curious to know why any users of the latest kernel on x86 might be invoking kernel_halt() instead of kernel_power_off().

Quoted 5 lines

Quoted 1 line
Do we really need both?
Probably not, as i said i do not disagree - i just think it should be more explicit. Make it a: "users of CPU models X beware" commit title, not 'remove inactive code' ...

My intent was to make the functional change in 1/9 and the NOP cleanup in 2/9.

Quoted 4 lines

So please list the affected hardware and list the affected boot parameter explicitly, in a well-titled commit that phases out this (very likely unused) compatibility hack and *document* the idle=poll workaround for ancient hardware.

There is no known list of affected hardware.

Quoted 7 lines

There's still i386DX CPUs being manufactured these days - a 20+ years old CPU design is surprisingly resilient to spurious patent claims, for obvious reasons.
Really, there's no need to do things by stealth. There's few things worse than doing the right thing for the wrong reason - it becomes a bad habit of subtly broken thinking quickly.

I agree completely, which is why I've sent this patch -- twice, so far -- to 5000 of my closest friends, including you:-)

thanks,
-Len

Len Brown

author reviewer

2011-03-31 18:08 UTC #41 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Ingo Molnar

Quoted 15 lines

Quoted 15 lines
Quoted 15 lines
Quoted 3 lines
hlt_works_ok was X86_32 only, initialized to 1, and never cleared.
On 32-bit kernels, this deletes a line from /proc/cpuinfo: "hlt_bug : no"
I think you missed the valid usecase where an old CPU with broken halt is booted with the no-hlt boot parameter and does not want to crash in the HLT instruction.
That "no-hlt" boot parameter does:
  arch/x86/kernel/cpu/bugs.c:     boot_cpu_data.hlt_works_ok = 0;
We can restrict compatibility, but *please* lets do it *explicitly*, not under some 'remove unused code' pretense ...

Quoted 7 lines

Quoted 4 lines
Quoted 1 line
Could you please list all CPU models that are affected?
"no-hlt" existed only for 32-bit, and there were exactly zero automatic invocations of it.
Do we know whether a distro adds this to the boot line? Do we know about users relying on it.

Impossible to know.

Quoted 4 lines

Quoted 2 lines
"idle=poll" does the same thing -- sans change a line in /proc/cpuinfo.
It also has an effect on halt/poweroff, right?

Yes, if somebody invokes kernel_halt(), then it
uses stop_this_cpu(), which uses HLT unless this flag is cleared.

The functional change of deleting "no-hlt", which was the only way to clear this flag, was in the previous patch, and so I should have mentioned it here.

stop_this_cpu() is not in the poweroff path.

It is a different topic, but I'd be curious to know why any users of the latest kernel on x86 might be invoking kernel_halt() instead of kernel_power_off().

Quoted 5 lines

Quoted 1 line
Do we really need both?
Probably not, as i said i do not disagree - i just think it should be more explicit. Make it a: "users of CPU models X beware" commit title, not 'remove inactive code' ...

My intent was to make the functional change in 1/9 and the NOP cleanup in 2/9.

Quoted 4 lines

So please list the affected hardware and list the affected boot parameter explicitly, in a well-titled commit that phases out this (very likely unused) compatibility hack and *document* the idle=poll workaround for ancient hardware.

There is no known list of affected hardware.

Quoted 7 lines

There's still i386DX CPUs being manufactured these days - a 20+ years old CPU design is surprisingly resilient to spurious patent claims, for obvious reasons.
Really, there's no need to do things by stealth. There's few things worse than doing the right thing for the wrong reason - it becomes a bad habit of subtly broken thinking quickly.

I agree completely, which is why I've sent this patch -- twice, so far -- to 5000 of my closest friends, including you:-)

thanks,
-Len

H. Peter Anvin

reviewer

2011-03-31 18:28 UTC #42 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

Quoted 6 lines · Len Brown

Quoted 3 lines
Do we know whether a distro adds this to the boot line? Do we know about users relying on it.
Impossible to know.

The first would be insanely unlikely, as the machines with HLT problems were already getting old by the time Linux distributions started appearing in significant numbers.

Users relying on it is another issue.

-hpa

Signature · 2 lines

H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

H. Peter Anvin

reviewer

2011-03-31 18:29 UTC #43 lore raw

Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag

In reply to Len Brown

Quoted 6 lines · Len Brown

Quoted 3 lines
Do we know whether a distro adds this to the boot line? Do we know about users relying on it.
Impossible to know.

The first would be insanely unlikely, as the machines with HLT problems were already getting old by the time Linux distributions started appearing in significant numbers.

Users relying on it is another issue.

-hpa

Signature · 2 lines

H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

Len Brown

author reviewer

2011-03-31 06:03 UTC #44 lore raw

PATCH 3/9 x86 idle: remove NOP halt_works()

In reply to Len Brown

From: Len Brown <[email protected]>

no functional change

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |    5 -----
 arch/x86/kernel/process.c        |    3 +--
 2 files changed, 1 insertions(+), 7 deletions(-)

arch/x86/include/asm/processor.h +0 -5

index b5c83f1..8776232 100644
@@ -147,11 +147,6 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
 
 extern const struct seq_operations cpuinfo_op;
 
-static inline int hlt_works(int cpu)
-{
-	return 1;
-}
-
 #define cache_line_size()	(boot_cpu_data.x86_cache_alignment)
 
 extern void cpu_detect(struct cpuinfo_x86 *c);

arch/x86/kernel/process.c +1 -2

index 4966c7e..cd461c3 100644
@@ -414,8 +414,7 @@ void stop_this_cpu(void *dummy)
 	disable_local_APIC();
 
 	for (;;) {
-		if (hlt_works(smp_processor_id()))
-			halt();
+		halt();
 	}
 }

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:03 UTC #45 lore raw

PATCH 3/9 x86 idle: remove NOP halt_works()

In reply to Len Brown

From: Len Brown <[email protected]>

no functional change

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |    5 -----
 arch/x86/kernel/process.c        |    3 +--
 2 files changed, 1 insertions(+), 7 deletions(-)

arch/x86/include/asm/processor.h +0 -5

index b5c83f1..8776232 100644
@@ -147,11 +147,6 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
 
 extern const struct seq_operations cpuinfo_op;
 
-static inline int hlt_works(int cpu)
-{
-	return 1;
-}
-
 #define cache_line_size()	(boot_cpu_data.x86_cache_alignment)
 
 extern void cpu_detect(struct cpuinfo_x86 *c);

arch/x86/kernel/process.c +1 -2

index 4966c7e..cd461c3 100644
@@ -414,8 +414,7 @@ void stop_this_cpu(void *dummy)
 	disable_local_APIC();
 
 	for (;;) {
-		if (hlt_works(smp_processor_id()))
-			halt();
+		halt();
 	}
 }

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:03 UTC #46 lore raw

PATCH 4/9 x86 idle floppy: delete disable_hlt()/enable_hlt()

In reply to Len Brown

From: Len Brown <[email protected]>

The X86_32-only disable_hlt/enable_hlt mechanism was used by the 32-bit floppy driver. Its effect was to replace the use of the HLT instruction inside default_idle() with cpu_relax().

Unlcear why this workaround was ever needed, it was commented:

floppy.c said:

"disable hlt during certain critical i/o operations"

x86/kernel/process.c said:

"This halt magic was a workaround for ancient floppy DMA
wreckage. It should be safe to remove."

So remove it, as it allows us to simplify the x86 idle code.

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/system.h |    7 -------
 arch/x86/kernel/process.c     |   24 ------------------------
 drivers/block/floppy.c        |   35 -----------------------------------
 3 files changed, 0 insertions(+), 66 deletions(-)

arch/x86/include/asm/system.h +0 -7

index 33ecc3e..013dd42 100644
@@ -93,10 +93,6 @@ do {									\
 			"memory");					\
 } while (0)
 
-/*
- * disable hlt during certain critical i/o operations
- */
-#define HAVE_DISABLE_HLT
 #else
 #define __SAVE(reg, offset) "movq %%" #reg ",(14-" #offset ")*8(%%rsp)\n\t"
 #define __RESTORE(reg, offset) "movq (14-" #offset ")*8(%%rsp),%%" #reg "\n\t"

@@ -337,9 +333,6 @@ static inline void clflush(volatile void *__p)
 
 #define nop() asm volatile ("nop")
 
-void disable_hlt(void);
-void enable_hlt(void);
-
 void cpu_idle_wait(void);
 
 extern unsigned long arch_align_stack(unsigned long sp);

arch/x86/kernel/process.c +0 ~~-24~~

index cd461c3..8688ade 100644
@@ -342,34 +342,10 @@ EXPORT_SYMBOL(boot_option_idle_override);
 void (*pm_idle)(void);
 EXPORT_SYMBOL(pm_idle);
 
-#ifdef CONFIG_X86_32
-/*
- * This halt magic was a workaround for ancient floppy DMA
- * wreckage. It should be safe to remove.
- */
-static int hlt_counter;
-void disable_hlt(void)
-{
-	hlt_counter++;
-}
-EXPORT_SYMBOL(disable_hlt);
-
-void enable_hlt(void)
-{
-	hlt_counter--;
-}
-EXPORT_SYMBOL(enable_hlt);
-
-static inline int hlt_use_halt(void)
-{
-	return (!hlt_counter);
-}
-#else
 static inline int hlt_use_halt(void)
 {
 	return 1;
 }
-#endif
 
 /*
  * We use this if we don't have any better

drivers/block/floppy.c +0 ~~-35~~

index 77fc76f..9a4e006 100644
@@ -1032,36 +1032,6 @@ static int fd_wait_for_completion(unsigned long delay, timeout_fn function)
 	return 0;
 }
 
-static DEFINE_SPINLOCK(floppy_hlt_lock);
-static int hlt_disabled;
-static void floppy_disable_hlt(void)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&floppy_hlt_lock, flags);
-	if (!hlt_disabled) {
-		hlt_disabled = 1;
-#ifdef HAVE_DISABLE_HLT
-		disable_hlt();
-#endif
-	}
-	spin_unlock_irqrestore(&floppy_hlt_lock, flags);
-}
-
-static void floppy_enable_hlt(void)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&floppy_hlt_lock, flags);
-	if (hlt_disabled) {
-		hlt_disabled = 0;
-#ifdef HAVE_DISABLE_HLT
-		enable_hlt();
-#endif
-	}
-	spin_unlock_irqrestore(&floppy_hlt_lock, flags);
-}
-
 static void setup_DMA(void)
 {
 	unsigned long f;

@@ -1106,7 +1076,6 @@ static void setup_DMA(void)
 	fd_enable_dma();
 	release_dma_lock(f);
 #endif
-	floppy_disable_hlt();
 }
 
 static void show_floppy(void);

@@ -1708,7 +1677,6 @@ irqreturn_t floppy_interrupt(int irq, void *dev_id)
 	fd_disable_dma();
 	release_dma_lock(f);
 
-	floppy_enable_hlt();
 	do_floppy = NULL;
 	if (fdc >= N_FDC || FDCS->address == -1) {
 		/* we don't even know which FDC is the culprit */

@@ -1857,8 +1825,6 @@ static void floppy_shutdown(unsigned long data)
 		show_floppy();
 	cancel_activity();
 
-	floppy_enable_hlt();
-
 	flags = claim_dma_lock();
 	fd_disable_dma();
 	release_dma_lock(flags);

@@ -4503,7 +4469,6 @@ static void floppy_release_irq_and_dma(void)
 #if N_FDC > 1
 	set_dor(1, ~8, 0);
 #endif
-	floppy_enable_hlt();
 
 	if (floppy_track_buffer && max_buffer_sectors) {
 		tmpsize = max_buffer_sectors * 1024;

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:05 UTC #47 lore raw

PATCH 4/9 x86 idle floppy: delete disable_hlt()/enable_hlt()

In reply to Len Brown

From: Len Brown <[email protected]>

The X86_32-only disable_hlt/enable_hlt mechanism was used by the 32-bit floppy driver. Its effect was to replace the use of the HLT instruction inside default_idle() with cpu_relax().

Unlcear why this workaround was ever needed, it was commented:

floppy.c said:

"disable hlt during certain critical i/o operations"

x86/kernel/process.c said:

"This halt magic was a workaround for ancient floppy DMA
wreckage. It should be safe to remove."

So remove it, as it allows us to simplify the x86 idle code.

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/system.h |    7 -------
 arch/x86/kernel/process.c     |   24 ------------------------
 drivers/block/floppy.c        |   35 -----------------------------------
 3 files changed, 0 insertions(+), 66 deletions(-)

arch/x86/include/asm/system.h +0 -7

index 33ecc3e..013dd42 100644
@@ -93,10 +93,6 @@ do {									\
 			"memory");					\
 } while (0)
 
-/*
- * disable hlt during certain critical i/o operations
- */
-#define HAVE_DISABLE_HLT
 #else
 #define __SAVE(reg, offset) "movq %%" #reg ",(14-" #offset ")*8(%%rsp)\n\t"
 #define __RESTORE(reg, offset) "movq (14-" #offset ")*8(%%rsp),%%" #reg "\n\t"

@@ -337,9 +333,6 @@ static inline void clflush(volatile void *__p)
 
 #define nop() asm volatile ("nop")
 
-void disable_hlt(void);
-void enable_hlt(void);
-
 void cpu_idle_wait(void);
 
 extern unsigned long arch_align_stack(unsigned long sp);

arch/x86/kernel/process.c +0 ~~-24~~

index cd461c3..8688ade 100644
@@ -342,34 +342,10 @@ EXPORT_SYMBOL(boot_option_idle_override);
 void (*pm_idle)(void);
 EXPORT_SYMBOL(pm_idle);
 
-#ifdef CONFIG_X86_32
-/*
- * This halt magic was a workaround for ancient floppy DMA
- * wreckage. It should be safe to remove.
- */
-static int hlt_counter;
-void disable_hlt(void)
-{
-	hlt_counter++;
-}
-EXPORT_SYMBOL(disable_hlt);
-
-void enable_hlt(void)
-{
-	hlt_counter--;
-}
-EXPORT_SYMBOL(enable_hlt);
-
-static inline int hlt_use_halt(void)
-{
-	return (!hlt_counter);
-}
-#else
 static inline int hlt_use_halt(void)
 {
 	return 1;
 }
-#endif
 
 /*
  * We use this if we don't have any better

drivers/block/floppy.c +0 ~~-35~~

index 77fc76f..9a4e006 100644
@@ -1032,36 +1032,6 @@ static int fd_wait_for_completion(unsigned long delay, timeout_fn function)
 	return 0;
 }
 
-static DEFINE_SPINLOCK(floppy_hlt_lock);
-static int hlt_disabled;
-static void floppy_disable_hlt(void)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&floppy_hlt_lock, flags);
-	if (!hlt_disabled) {
-		hlt_disabled = 1;
-#ifdef HAVE_DISABLE_HLT
-		disable_hlt();
-#endif
-	}
-	spin_unlock_irqrestore(&floppy_hlt_lock, flags);
-}
-
-static void floppy_enable_hlt(void)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&floppy_hlt_lock, flags);
-	if (hlt_disabled) {
-		hlt_disabled = 0;
-#ifdef HAVE_DISABLE_HLT
-		enable_hlt();
-#endif
-	}
-	spin_unlock_irqrestore(&floppy_hlt_lock, flags);
-}
-
 static void setup_DMA(void)
 {
 	unsigned long f;

@@ -1106,7 +1076,6 @@ static void setup_DMA(void)
 	fd_enable_dma();
 	release_dma_lock(f);
 #endif
-	floppy_disable_hlt();
 }
 
 static void show_floppy(void);

@@ -1708,7 +1677,6 @@ irqreturn_t floppy_interrupt(int irq, void *dev_id)
 	fd_disable_dma();
 	release_dma_lock(f);
 
-	floppy_enable_hlt();
 	do_floppy = NULL;
 	if (fdc >= N_FDC || FDCS->address == -1) {
 		/* we don't even know which FDC is the culprit */

@@ -1857,8 +1825,6 @@ static void floppy_shutdown(unsigned long data)
 		show_floppy();
 	cancel_activity();
 
-	floppy_enable_hlt();
-
 	flags = claim_dma_lock();
 	fd_disable_dma();
 	release_dma_lock(flags);

@@ -4503,7 +4469,6 @@ static void floppy_release_irq_and_dma(void)
 #if N_FDC > 1
 	set_dor(1, ~8, 0);
 #endif
-	floppy_enable_hlt();
 
 	if (floppy_track_buffer && max_buffer_sectors) {
 		tmpsize = max_buffer_sectors * 1024;

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:03 UTC #48 lore raw

PATCH 5/9 x86 idle: remove NOP hlt_use_halt()

In reply to Len Brown

From: Len Brown <[email protected]>

hlt_use_halt() no longer has any effect, except to complicate the indentation in default_idle().

no functional change.

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/kernel/process.c |   39 ++++++++++++++-------------------------
 1 files changed, 14 insertions(+), 25 deletions(-)

arch/x86/kernel/process.c +14 ~~-25~~

index 8688ade..094d4ac 100644
@@ -342,39 +342,28 @@ EXPORT_SYMBOL(boot_option_idle_override);
 void (*pm_idle)(void);
 EXPORT_SYMBOL(pm_idle);
 
-static inline int hlt_use_halt(void)
-{
-	return 1;
-}
-
 /*
  * We use this if we don't have any better
  * idle routine..
  */
 void default_idle(void)
 {
-	if (hlt_use_halt()) {
-		trace_power_start(POWER_CSTATE, 1, smp_processor_id());
-		trace_cpu_idle(1, smp_processor_id());
-		current_thread_info()->status &= ~TS_POLLING;
-		/*
-		 * TS_POLLING-cleared state must be visible before we
-		 * test NEED_RESCHED:
-		 */
-		smp_mb();
+	trace_power_start(POWER_CSTATE, 1, smp_processor_id());
+	trace_cpu_idle(1, smp_processor_id());
+	current_thread_info()->status &= ~TS_POLLING;
+	/*
+	 * TS_POLLING-cleared state must be visible before we
+	 * test NEED_RESCHED:
+	 */
+	smp_mb();
 
-		if (!need_resched())
-			safe_halt();	/* enables interrupts racelessly */
-		else
-			local_irq_enable();
-		current_thread_info()->status |= TS_POLLING;
-		trace_power_end(smp_processor_id());
-		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
-	} else {
+	if (!need_resched())
+		safe_halt();	/* enables interrupts racelessly */
+	else
 		local_irq_enable();
-		/* loop is done by the caller */
-		cpu_relax();
-	}
+	current_thread_info()->status |= TS_POLLING;
+	trace_power_end(smp_processor_id());
+	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
 }
 #ifdef CONFIG_APM_MODULE
 EXPORT_SYMBOL(default_idle);

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:05 UTC #49 lore raw

PATCH 5/9 x86 idle: remove NOP hlt_use_halt()

In reply to Len Brown

From: Len Brown <[email protected]>

hlt_use_halt() no longer has any effect, except to complicate the indentation in default_idle().

no functional change.

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/kernel/process.c |   39 ++++++++++++++-------------------------
 1 files changed, 14 insertions(+), 25 deletions(-)

arch/x86/kernel/process.c +14 ~~-25~~

index 8688ade..094d4ac 100644
@@ -342,39 +342,28 @@ EXPORT_SYMBOL(boot_option_idle_override);
 void (*pm_idle)(void);
 EXPORT_SYMBOL(pm_idle);
 
-static inline int hlt_use_halt(void)
-{
-	return 1;
-}
-
 /*
  * We use this if we don't have any better
  * idle routine..
  */
 void default_idle(void)
 {
-	if (hlt_use_halt()) {
-		trace_power_start(POWER_CSTATE, 1, smp_processor_id());
-		trace_cpu_idle(1, smp_processor_id());
-		current_thread_info()->status &= ~TS_POLLING;
-		/*
-		 * TS_POLLING-cleared state must be visible before we
-		 * test NEED_RESCHED:
-		 */
-		smp_mb();
+	trace_power_start(POWER_CSTATE, 1, smp_processor_id());
+	trace_cpu_idle(1, smp_processor_id());
+	current_thread_info()->status &= ~TS_POLLING;
+	/*
+	 * TS_POLLING-cleared state must be visible before we
+	 * test NEED_RESCHED:
+	 */
+	smp_mb();
 
-		if (!need_resched())
-			safe_halt();	/* enables interrupts racelessly */
-		else
-			local_irq_enable();
-		current_thread_info()->status |= TS_POLLING;
-		trace_power_end(smp_processor_id());
-		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
-	} else {
+	if (!need_resched())
+		safe_halt();	/* enables interrupts racelessly */
+	else
 		local_irq_enable();
-		/* loop is done by the caller */
-		cpu_relax();
-	}
+	current_thread_info()->status |= TS_POLLING;
+	trace_power_end(smp_processor_id());
+	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
 }
 #ifdef CONFIG_APM_MODULE
 EXPORT_SYMBOL(default_idle);

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:03 UTC #50 lore raw

PATCH 6/9 x86 idle APM: delete apm_cpu_idle(), and its use of (pm_idle)()

In reply to Len Brown

From: Len Brown <[email protected]>

There is some doubt whether the APM idle feature to call into the BIOS from the idle loop is reliable. Certainly it was known to fail on some machines, but more importantly, APM machines have not shipped for a decade and so finding machines to test the code is problematic.

After this patch, systems running in APM mode will simply run default_idle() and HALT without calling into the BIOS from their idle loop.

This deletes modular use use of (pm_idle)() and default_idle().

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/Kconfig         |   11 --
 arch/x86/kernel/apm_32.c |  232 ----------------------------------------------
 2 files changed, 0 insertions(+), 243 deletions(-)

arch/x86/Kconfig +0 ~~-11~~

index d5ed94d..681bb25 100644
@@ -1809,17 +1809,6 @@ config APM_DO_ENABLE
 	  T400CDT. This is off by default since most machines do fine without
 	  this feature.
 
-config APM_CPU_IDLE
-	bool "Make CPU Idle calls when idle"
-	---help---
-	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
-	  On some machines, this can activate improved power savings, such as
-	  a slowed CPU clock rate, when the machine is idle. These idle calls
-	  are made after the idle loop has run for some length of time (e.g.,
-	  333 mS). On some machines, this will cause a hang at boot time or
-	  whenever the CPU becomes idle. (On machines with more than one CPU,
-	  this option does nothing.)
-
 config APM_DISPLAY_BLANK
 	bool "Enable console blanking using APM"
 	---help---

arch/x86/kernel/apm_32.c +0 ~~-232~~

304 lines not on this page · raw message

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:03 UTC #51 lore raw

PATCH 6/9 x86 idle APM: delete apm_cpu_idle(), and its use of (pm_idle)()

In reply to Len Brown

From: Len Brown <[email protected]>

After this patch, systems running in APM mode will simply run default_idle() and HALT without calling into the BIOS from their idle loop.

This deletes modular use use of (pm_idle)() and default_idle().

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/Kconfig         |   11 --
 arch/x86/kernel/apm_32.c |  232 ----------------------------------------------
 2 files changed, 0 insertions(+), 243 deletions(-)

arch/x86/Kconfig +0 ~~-11~~

index d5ed94d..681bb25 100644
@@ -1809,17 +1809,6 @@ config APM_DO_ENABLE
 	  T400CDT. This is off by default since most machines do fine without
 	  this feature.
 
-config APM_CPU_IDLE
-	bool "Make CPU Idle calls when idle"
-	---help---
-	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
-	  On some machines, this can activate improved power savings, such as
-	  a slowed CPU clock rate, when the machine is idle. These idle calls
-	  are made after the idle loop has run for some length of time (e.g.,
-	  333 mS). On some machines, this will cause a hang at boot time or
-	  whenever the CPU becomes idle. (On machines with more than one CPU,
-	  this option does nothing.)
-
 config APM_DISPLAY_BLANK
 	bool "Enable console blanking using APM"
 	---help---

arch/x86/kernel/apm_32.c +0 ~~-232~~

304 lines not on this page · raw message

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:03 UTC #52 lore raw

PATCH 7/9 x86 idle: do not EXPORT_SYMBOL pm_idle and default_idle

In reply to Len Brown

From: Len Brown <[email protected]>

APM was the only potential modular user of pm_idle, and default_idle(), and that use is now gone.

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/kernel/process.c |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

arch/x86/kernel/process.c +0 -4

index 094d4ac..9d485d9 100644
@@ -340,7 +340,6 @@ EXPORT_SYMBOL(boot_option_idle_override);
  * Powermanagement idle function, if any..
  */
 void (*pm_idle)(void);
-EXPORT_SYMBOL(pm_idle);
 
 /*
  * We use this if we don't have any better

@@ -365,9 +364,6 @@ void default_idle(void)
 	trace_power_end(smp_processor_id());
 	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
 }
-#ifdef CONFIG_APM_MODULE
-EXPORT_SYMBOL(default_idle);
-#endif
 
 void stop_this_cpu(void *dummy)
 {

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:04 UTC #53 lore raw

PATCH 7/9 x86 idle: do not EXPORT_SYMBOL pm_idle and default_idle

In reply to Len Brown

From: Len Brown <[email protected]>

APM was the only potential modular user of pm_idle, and default_idle(), and that use is now gone.

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/kernel/process.c |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

arch/x86/kernel/process.c +0 -4

index 094d4ac..9d485d9 100644
@@ -340,7 +340,6 @@ EXPORT_SYMBOL(boot_option_idle_override);
  * Powermanagement idle function, if any..
  */
 void (*pm_idle)(void);
-EXPORT_SYMBOL(pm_idle);
 
 /*
  * We use this if we don't have any better

@@ -365,9 +364,6 @@ void default_idle(void)
 	trace_power_end(smp_processor_id());
 	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
 }
-#ifdef CONFIG_APM_MODULE
-EXPORT_SYMBOL(default_idle);
-#endif
 
 void stop_this_cpu(void *dummy)
 {

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:03 UTC #54 lore raw

PATCH 8/9 x86 idle: move mwait_idle_with_hints() to where it is used

In reply to Len Brown

From: Len Brown <[email protected]>

no functional change

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |    2 --
 arch/x86/kernel/acpi/cstate.c    |   24 ++++++++++++++++++++++++
 arch/x86/kernel/process.c        |   23 -----------------------
 3 files changed, 24 insertions(+), 25 deletions(-)

arch/x86/include/asm/processor.h +0 -2

index 8776232..3b288ca 100644
@@ -745,8 +745,6 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
 		     :: "a" (eax), "c" (ecx));
 }
 
-extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
-
 extern void select_idle_routine(const struct cpuinfo_x86 *c);
 extern void init_c1e_mask(void);

arch/x86/kernel/acpi/cstate.c +24 -0

index 5812404..c49281e 100644
@@ -149,6 +149,30 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
 }
 EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
 
+/*
+ * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
+ * which can obviate IPI to trigger checking of need_resched.
+ * We execute MONITOR against need_resched and enter optimized wait state
+ * through MWAIT. Whenever someone changes need_resched, we would be woken
+ * up from MWAIT (without an IPI).
+ *
+ * New with Core Duo processors, MWAIT can take some hints based on CPU
+ * capability.
+ */
+static void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
+{
+	if (!need_resched()) {
+		if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
+			clflush((void *)&current_thread_info()->flags);
+
+		__monitor((void *)&current_thread_info()->flags, 0, 0);
+		smp_mb();
+		if (!need_resched())
+			__mwait(ax, cx);
+	}
+}
+
+
 void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx)
 {
 	unsigned int cpu = smp_processor_id();

arch/x86/kernel/process.c +0 ~~-23~~

index 9d485d9..9f08e7b 100644
@@ -399,29 +399,6 @@ void cpu_idle_wait(void)
 }
 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 
-/*
- * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
- * which can obviate IPI to trigger checking of need_resched.
- * We execute MONITOR against need_resched and enter optimized wait state
- * through MWAIT. Whenever someone changes need_resched, we would be woken
- * up from MWAIT (without an IPI).
- *
- * New with Core Duo processors, MWAIT can take some hints based on CPU
- * capability.
- */
-void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
-{
-	if (!need_resched()) {
-		if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
-			clflush((void *)&current_thread_info()->flags);
-
-		__monitor((void *)&current_thread_info()->flags, 0, 0);
-		smp_mb();
-		if (!need_resched())
-			__mwait(ax, cx);
-	}
-}
-
 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
 static void mwait_idle(void)
 {

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:04 UTC #55 lore raw

PATCH 8/9 x86 idle: move mwait_idle_with_hints() to where it is used

In reply to Len Brown

From: Len Brown <[email protected]>

no functional change

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |    2 --
 arch/x86/kernel/acpi/cstate.c    |   24 ++++++++++++++++++++++++
 arch/x86/kernel/process.c        |   23 -----------------------
 3 files changed, 24 insertions(+), 25 deletions(-)

arch/x86/include/asm/processor.h +0 -2

index 8776232..3b288ca 100644
@@ -745,8 +745,6 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
 		     :: "a" (eax), "c" (ecx));
 }
 
-extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
-
 extern void select_idle_routine(const struct cpuinfo_x86 *c);
 extern void init_c1e_mask(void);

arch/x86/kernel/acpi/cstate.c +24 -0

index 5812404..c49281e 100644
@@ -149,6 +149,30 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
 }
 EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
 
+/*
+ * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
+ * which can obviate IPI to trigger checking of need_resched.
+ * We execute MONITOR against need_resched and enter optimized wait state
+ * through MWAIT. Whenever someone changes need_resched, we would be woken
+ * up from MWAIT (without an IPI).
+ *
+ * New with Core Duo processors, MWAIT can take some hints based on CPU
+ * capability.
+ */
+static void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
+{
+	if (!need_resched()) {
+		if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
+			clflush((void *)&current_thread_info()->flags);
+
+		__monitor((void *)&current_thread_info()->flags, 0, 0);
+		smp_mb();
+		if (!need_resched())
+			__mwait(ax, cx);
+	}
+}
+
+
 void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx)
 {
 	unsigned int cpu = smp_processor_id();

arch/x86/kernel/process.c +0 ~~-23~~

index 9d485d9..9f08e7b 100644
@@ -399,29 +399,6 @@ void cpu_idle_wait(void)
 }
 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 
-/*
- * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
- * which can obviate IPI to trigger checking of need_resched.
- * We execute MONITOR against need_resched and enter optimized wait state
- * through MWAIT. Whenever someone changes need_resched, we would be woken
- * up from MWAIT (without an IPI).
- *
- * New with Core Duo processors, MWAIT can take some hints based on CPU
- * capability.
- */
-void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
-{
-	if (!need_resched()) {
-		if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
-			clflush((void *)&current_thread_info()->flags);
-
-		__monitor((void *)&current_thread_info()->flags, 0, 0);
-		smp_mb();
-		if (!need_resched())
-			__mwait(ax, cx);
-	}
-}
-
 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
 static void mwait_idle(void)
 {

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:03 UTC #56 lore raw

PATCH 9/9 x86 idle: delete mwait_idle()

In reply to Len Brown

From: Len Brown <[email protected]>

For ACPI mode, mwait_with_hints() in cstate.c is used instead of process.c's mwait_idle().

For INTEL_IDLE mode, the mwait in intel_idle() is used instead of process.c's mwait_idle().

So delete process.c's mwait_idle().
This will change the behaviour of SMP sysgtems that are running !ACPI and !INTEL_IDLE kernels -- they will use HALT instead of MWAIT.

This deletes the "idle=mwait" parameter, and thus the boot_option_idle_override == IDLE_FORCE_MWAIT flag.

Signed-off-by Len Brown <[email protected]>

---
 Documentation/kernel-parameters.txt |    7 +------
 arch/x86/include/asm/processor.h    |    2 +-
 arch/x86/kernel/process.c           |   34 +---------------------------------
 drivers/acpi/processor_idle.c       |    1 -
 4 files changed, 3 insertions(+), 41 deletions(-)

Documentation/kernel-parameters.txt +1 -6

index e6b4843..ce9624a 100644
@@ -917,16 +917,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			Claim all unknown PCI IDE storage controllers.
 
 	idle=		[X86]
-			Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
+			Format: idle=poll, idle=halt, idle=nomwait
 			Poll forces a polling idle loop that can slightly
 			improve the performance of waking up a idle CPU, but
 			will use a lot of power and make the system run hot.
 			Not recommended.
-			idle=mwait: On systems which support MONITOR/MWAIT but
-			the kernel chose to not use it because it doesn't save
-			as much power as a normal idle loop, use the
-			MONITOR/MWAIT idle loop anyways. Performance should be
-			the same as idle=poll.
 			idle=halt: Halt is forced to be used for CPU idle.
 			In such case C2/C3 won't be used again.
 			idle=nomwait: Disable mwait for CPU C-states

arch/x86/include/asm/processor.h +1 -1

index 3b288ca..0d8d2a4 100644
@@ -752,7 +752,7 @@ extern unsigned long		boot_option_idle_override;
 extern bool			c1e_detected;
 
 enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
-			 IDLE_POLL, IDLE_FORCE_MWAIT};
+			 IDLE_POLL};
 
 extern void enable_sep_cpu(void);
 extern int sysenter_setup(void);

arch/x86/kernel/process.c +1 ~~-33~~

index 9f08e7b..4b93d50 100644
@@ -399,27 +399,6 @@ void cpu_idle_wait(void)
 }
 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 
-/* Default MONITOR/MWAIT with no hints, used for default C1 state */
-static void mwait_idle(void)
-{
-	if (!need_resched()) {
-		trace_power_start(POWER_CSTATE, 1, smp_processor_id());
-		trace_cpu_idle(1, smp_processor_id());
-		if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
-			clflush((void *)&current_thread_info()->flags);
-
-		__monitor((void *)&current_thread_info()->flags, 0, 0);
-		smp_mb();
-		if (!need_resched())
-			__sti_mwait(0, 0);
-		else
-			local_irq_enable();
-		trace_power_end(smp_processor_id());
-		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
-	} else
-		local_irq_enable();
-}
-
 /*
  * On SMP it's slightly faster (but much more power-consuming!)
  * to poll the ->work.need_resched flag instead of waiting for the

@@ -457,9 +436,6 @@ int mwait_usable(const struct cpuinfo_x86 *c)
 {
 	u32 eax, ebx, ecx, edx;
 
-	if (boot_option_idle_override == IDLE_FORCE_MWAIT)
-		return 1;
-
 	if (c->cpuid_level < MWAIT_INFO)
 		return 0;

@@ -548,13 +524,7 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 	if (pm_idle)
 		return;
 
-	if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
-		/*
-		 * One CPU supports mwait => All CPUs supports mwait
-		 */
-		printk(KERN_INFO "using mwait in idle threads.\n");
-		pm_idle = mwait_idle;
-	} else if (cpu_has_amd_erratum(amd_erratum_400)) {
+	if (cpu_has_amd_erratum(amd_erratum_400)) {
 		/* E400: APIC timer interrupt does not wake up CPU from C1e */
 		printk(KERN_INFO "using C1E aware idle routine\n");
 		pm_idle = c1e_idle;

@@ -578,8 +548,6 @@ static int __init idle_setup(char *str)
 		printk("using polling idle threads.\n");
 		pm_idle = poll_idle;
 		boot_option_idle_override = IDLE_POLL;
-	} else if (!strcmp(str, "mwait")) {
-		boot_option_idle_override = IDLE_FORCE_MWAIT;
 	} else if (!strcmp(str, "halt")) {
 		/*
 		 * When the boot option of idle=halt is added, halt is

drivers/acpi/processor_idle.c +0 -1

index d615b7d..a15390c 100644
@@ -82,7 +82,6 @@ module_param(latency_factor, uint, 0644);
 static int disabled_by_idle_boot_param(void)
 {
 	return boot_option_idle_override == IDLE_POLL ||
-		boot_option_idle_override == IDLE_FORCE_MWAIT ||
 		boot_option_idle_override == IDLE_HALT;
 }

Signature · 1 line

1.7.4.2.406.gbe91

Len Brown

author reviewer

2011-03-31 06:03 UTC #57 lore raw

PATCH 9/9 x86 idle: delete mwait_idle()

In reply to Len Brown

From: Len Brown <[email protected]>

For ACPI mode, mwait_with_hints() in cstate.c is used instead of process.c's mwait_idle().

For INTEL_IDLE mode, the mwait in intel_idle() is used instead of process.c's mwait_idle().

So delete process.c's mwait_idle().
This will change the behaviour of SMP sysgtems that are running !ACPI and !INTEL_IDLE kernels -- they will use HALT instead of MWAIT.

This deletes the "idle=mwait" parameter, and thus the boot_option_idle_override == IDLE_FORCE_MWAIT flag.

Signed-off-by Len Brown <[email protected]>

---
 Documentation/kernel-parameters.txt |    7 +------
 arch/x86/include/asm/processor.h    |    2 +-
 arch/x86/kernel/process.c           |   34 +---------------------------------
 drivers/acpi/processor_idle.c       |    1 -
 4 files changed, 3 insertions(+), 41 deletions(-)

Documentation/kernel-parameters.txt +1 -6

index e6b4843..ce9624a 100644
@@ -917,16 +917,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			Claim all unknown PCI IDE storage controllers.
 
 	idle=		[X86]
-			Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
+			Format: idle=poll, idle=halt, idle=nomwait
 			Poll forces a polling idle loop that can slightly
 			improve the performance of waking up a idle CPU, but
 			will use a lot of power and make the system run hot.
 			Not recommended.
-			idle=mwait: On systems which support MONITOR/MWAIT but
-			the kernel chose to not use it because it doesn't save
-			as much power as a normal idle loop, use the
-			MONITOR/MWAIT idle loop anyways. Performance should be
-			the same as idle=poll.
 			idle=halt: Halt is forced to be used for CPU idle.
 			In such case C2/C3 won't be used again.
 			idle=nomwait: Disable mwait for CPU C-states

arch/x86/include/asm/processor.h +1 -1

index 3b288ca..0d8d2a4 100644
@@ -752,7 +752,7 @@ extern unsigned long		boot_option_idle_override;
 extern bool			c1e_detected;
 
 enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
-			 IDLE_POLL, IDLE_FORCE_MWAIT};
+			 IDLE_POLL};
 
 extern void enable_sep_cpu(void);
 extern int sysenter_setup(void);

arch/x86/kernel/process.c +1 ~~-33~~

index 9f08e7b..4b93d50 100644
@@ -399,27 +399,6 @@ void cpu_idle_wait(void)
 }
 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 
-/* Default MONITOR/MWAIT with no hints, used for default C1 state */
-static void mwait_idle(void)
-{
-	if (!need_resched()) {
-		trace_power_start(POWER_CSTATE, 1, smp_processor_id());
-		trace_cpu_idle(1, smp_processor_id());
-		if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
-			clflush((void *)&current_thread_info()->flags);
-
-		__monitor((void *)&current_thread_info()->flags, 0, 0);
-		smp_mb();
-		if (!need_resched())
-			__sti_mwait(0, 0);
-		else
-			local_irq_enable();
-		trace_power_end(smp_processor_id());
-		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
-	} else
-		local_irq_enable();
-}
-
 /*
  * On SMP it's slightly faster (but much more power-consuming!)
  * to poll the ->work.need_resched flag instead of waiting for the

@@ -457,9 +436,6 @@ int mwait_usable(const struct cpuinfo_x86 *c)
 {
 	u32 eax, ebx, ecx, edx;
 
-	if (boot_option_idle_override == IDLE_FORCE_MWAIT)
-		return 1;
-
 	if (c->cpuid_level < MWAIT_INFO)
 		return 0;

@@ -548,13 +524,7 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 	if (pm_idle)
 		return;
 
-	if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
-		/*
-		 * One CPU supports mwait => All CPUs supports mwait
-		 */
-		printk(KERN_INFO "using mwait in idle threads.\n");
-		pm_idle = mwait_idle;
-	} else if (cpu_has_amd_erratum(amd_erratum_400)) {
+	if (cpu_has_amd_erratum(amd_erratum_400)) {
 		/* E400: APIC timer interrupt does not wake up CPU from C1e */
 		printk(KERN_INFO "using C1E aware idle routine\n");
 		pm_idle = c1e_idle;

@@ -578,8 +548,6 @@ static int __init idle_setup(char *str)
 		printk("using polling idle threads.\n");
 		pm_idle = poll_idle;
 		boot_option_idle_override = IDLE_POLL;
-	} else if (!strcmp(str, "mwait")) {
-		boot_option_idle_override = IDLE_FORCE_MWAIT;
 	} else if (!strcmp(str, "halt")) {
 		/*
 		 * When the boot option of idle=halt is added, halt is

drivers/acpi/processor_idle.c +0 -1

index d615b7d..a15390c 100644
@@ -82,7 +82,6 @@ module_param(latency_factor, uint, 0644);
 static int disabled_by_idle_boot_param(void)
 {
 	return boot_option_idle_override == IDLE_POLL ||
-		boot_option_idle_override == IDLE_FORCE_MWAIT ||
 		boot_option_idle_override == IDLE_HALT;
 }

Signature · 1 line

1.7.4.2.406.gbe91

Andreas Herrmann

Acked-by on v1 9/9

2011-04-01 11:02 UTC #58 lore raw

Re: [PATCH 9/9] x86 idle: delete mwait_idle()

Quoted 13 lines · Len Brown

From: Len Brown <[email protected]>
For ACPI mode, mwait_with_hints() in cstate.c is used instead of process.c's mwait_idle().
For INTEL_IDLE mode, the mwait in intel_idle() is used instead of process.c's mwait_idle().
So delete process.c's mwait_idle().
This will change the behaviour of SMP sysgtems that are running !ACPI and !INTEL_IDLE kernels -- they will use HALT instead of MWAIT.

Quoted 4 lines

This deletes the "idle=mwait" parameter, and thus the boot_option_idle_override == IDLE_FORCE_MWAIT flag.
Signed-off-by Len Brown <[email protected]>

Acked-by Andreas Herrmann <[email protected]>

Regards,
Andreas

Andreas Herrmann

Acked-by on v1 9/9

2011-04-01 11:02 UTC #59 lore raw

Re: [PATCH 9/9] x86 idle: delete mwait_idle()

In reply to Len Brown

Quoted 13 lines · Len Brown

From: Len Brown <[email protected]>
For ACPI mode, mwait_with_hints() in cstate.c is used instead of process.c's mwait_idle().
For INTEL_IDLE mode, the mwait in intel_idle() is used instead of process.c's mwait_idle().
So delete process.c's mwait_idle().
This will change the behaviour of SMP sysgtems that are running !ACPI and !INTEL_IDLE kernels -- they will use HALT instead of MWAIT.

Quoted 4 lines

This deletes the "idle=mwait" parameter, and thus the boot_option_idle_override == IDLE_FORCE_MWAIT flag.
Signed-off-by Len Brown <[email protected]>

Acked-by Andreas Herrmann <[email protected]>

Regards,
Andreas

Trinabh Gupta

2011-03-31 06:39 UTC #60 lore raw

Re: [PATCH 0/9] x86 idle cruft removal - v2

In reply to Len Brown

Quoted 33 lines · Len Brown

unchanged:
[PATCH 1/9] x86 idle: remove "no-hlt" cmdline param [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag [PATCH 3/9] x86 idle: remove NOP halt_works()
[PATCH 4/9] x86 idle floppy: delete disable_hlt()/enable_hlt() [PATCH 5/9] x86 idle: remove NOP hlt_use_halt()
new:
[PATCH 6/9] x86 idle APM: delete apm_cpu_idle(), and its use of pm_idle [PATCH 7/9] x86 idle: do not EXPORT_SYMBOL pm_idle and default_idle [PATCH 8/9] x86 idle: move mwait_idle_with_hints() to where it is used [PATCH 9/9] x86 idle: delete mwait_idle()
  Documentation/kernel-parameters.txt |   11 +--
  arch/x86/Kconfig                    |   11 --
  arch/x86/include/asm/processor.h    |   14 +--
  arch/x86/include/asm/system.h       |    7 -
  arch/x86/kernel/acpi/cstate.c       |   24 ++++
  arch/x86/kernel/apm_32.c            |  232 -----------------------------------
  arch/x86/kernel/cpu/bugs.c          |   13 +--
  arch/x86/kernel/cpu/proc.c          |    2 -
  arch/x86/kernel/process.c           |  127 +++-----------------
  arch/x86/kernel/setup.c             |    4 +-
  arch/x86/xen/setup.c                |    3 -
  drivers/acpi/processor_idle.c       |    1 -
  drivers/block/floppy.c              |   35 ------
  13 files changed, 45 insertions(+), 439 deletions(-)
What is next:

Quoted 7 lines

handle c1e_idle() vs default_idle()
run-time check for AMD workaround enable as part of default_idle?
give xen_arch_setup default_idle() w/o having it touch pm_idle
perhaps it can simply set a flag to disable cpuidle...
which is what would run if the xen kernel were booted on raw iron. Or can we handle this
at compile time?

I guess it may be good to have a method to override cpuidle and force it to call default_idle from inside cpuidle_idle_call(). This could be useful for users other than xen in future. Ofcourse this override should not touch pm_idle (which would be removed anyway).

Provision is already there to call default_idle from inside cpuidle_idle_call(); we can use that after checking a flag?? Can we use something like boot_option_idle_override? Or set/unset flag through an API?

Quoted 4 lines

delete pm_idle
x86 will then use default_idle or cpuidle
allow cpuidle to use default_idle to handle the period
where it polls because cpus have not yet registered

If we remove pm_idle and directly call cpuidle, the check already exists to call default_idle until a cpuidle driver (and cpus) is registered.

-Trinabh

Trinabh Gupta

2011-03-31 06:39 UTC #61 lore raw

Re: [linux-pm] [PATCH 0/9] x86 idle cruft removal - v2

In reply to Len Brown

Quoted 33 lines · Len Brown

unchanged:
[PATCH 1/9] x86 idle: remove "no-hlt" cmdline param [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag [PATCH 3/9] x86 idle: remove NOP halt_works()
[PATCH 4/9] x86 idle floppy: delete disable_hlt()/enable_hlt() [PATCH 5/9] x86 idle: remove NOP hlt_use_halt()
new:
[PATCH 6/9] x86 idle APM: delete apm_cpu_idle(), and its use of pm_idle [PATCH 7/9] x86 idle: do not EXPORT_SYMBOL pm_idle and default_idle [PATCH 8/9] x86 idle: move mwait_idle_with_hints() to where it is used [PATCH 9/9] x86 idle: delete mwait_idle()
  Documentation/kernel-parameters.txt |   11 +--
  arch/x86/Kconfig                    |   11 --
  arch/x86/include/asm/processor.h    |   14 +--
  arch/x86/include/asm/system.h       |    7 -
  arch/x86/kernel/acpi/cstate.c       |   24 ++++
  arch/x86/kernel/apm_32.c            |  232 -----------------------------------
  arch/x86/kernel/cpu/bugs.c          |   13 +--
  arch/x86/kernel/cpu/proc.c          |    2 -
  arch/x86/kernel/process.c           |  127 +++-----------------
  arch/x86/kernel/setup.c             |    4 +-
  arch/x86/xen/setup.c                |    3 -
  drivers/acpi/processor_idle.c       |    1 -
  drivers/block/floppy.c              |   35 ------
  13 files changed, 45 insertions(+), 439 deletions(-)
What is next:

Quoted 7 lines

handle c1e_idle() vs default_idle()
run-time check for AMD workaround enable as part of default_idle?
give xen_arch_setup default_idle() w/o having it touch pm_idle
perhaps it can simply set a flag to disable cpuidle...
which is what would run if the xen kernel were booted on raw iron. Or can we handle this
at compile time?

I guess it may be good to have a method to override cpuidle and
force it to call default_idle from inside cpuidle_idle_call(). This
could be useful for users other than xen in future. Ofcourse this override should not touch pm_idle (which would be removed anyway).

Quoted 4 lines

delete pm_idle
x86 will then use default_idle or cpuidle
allow cpuidle to use default_idle to handle the period
where it polls because cpus have not yet registered

If we remove pm_idle and directly call cpuidle, the check already exists to call default_idle until a cpuidle driver (and cpus) is registered.

-Trinabh

Len Brown

author reviewer

2011-03-31 07:21 UTC #62 lore raw

Re: [PATCH 0/9] x86 idle cruft removal - v2

Quoted 10 lines

Quoted 9 lines
What is next:
handle c1e_idle() vs default_idle()
run-time check for AMD workaround enable as part of default_idle?
give xen_arch_setup default_idle() w/o having it touch pm_idle
perhaps it can simply set a flag to disable cpuidle...
which is what would run if the xen kernel were booted on raw iron. Or can we handle this
at compile time?

Quoted 4 lines

I guess it may be good to have a method to override cpuidle and force it to call default_idle from inside cpuidle_idle_call(). This could be useful for users other than xen in future. Ofcourse this override should not touch pm_idle (which would be removed anyway).

Actually what I was thinking was the ability to disable cpuidle altogether via cmdline. ie a run-time equivalent of CONFIG_CPU_IDLE=n. eg. "cpuidle=0" In that case cpu_idle_call() would return error and we'd have:

cpu_idle()

	if (cpu_idle_call())
		default_idle()

This is also a clean way for CONFIG_CPU_IDLE=n to work.

Quoted 4 lines

Provision is already there to call default_idle from inside cpuidle_idle_call(); we can use that after checking a flag?? Can we use something like boot_option_idle_override? Or set/unset flag through an API?

I think it is strange for cpuidle to turn around and call back to default_idle(). I'd like to see if we can keep knowledge of default_idle() inside process.c. If cpuidle can't do better than default_idle() then it sholdn't be running...

Quoted 8 lines

Quoted 4 lines
delete pm_idle
x86 will then use default_idle or cpuidle
allow cpuidle to use default_idle to handle the period
where it polls because cpus have not yet registered
If we remove pm_idle and directly call cpuidle, the check already exists to call default_idle until a cpuidle driver (and cpus) is registered.

it isn't working.
If it were, then we'd not see any polling in the cpuidle stats.

cheers,
-Len

Len Brown

author reviewer

2011-03-31 07:21 UTC #63 lore raw

Re: [linux-pm] [PATCH 0/9] x86 idle cruft removal - v2

In reply to Trinabh Gupta

Quoted 10 lines

Quoted 9 lines
What is next:
handle c1e_idle() vs default_idle()
run-time check for AMD workaround enable as part of default_idle?
give xen_arch_setup default_idle() w/o having it touch pm_idle
perhaps it can simply set a flag to disable cpuidle...
which is what would run if the xen kernel were booted on raw iron. Or can we handle this
at compile time?

Quoted 4 lines

I guess it may be good to have a method to override cpuidle and force it to call default_idle from inside cpuidle_idle_call(). This could be useful for users other than xen in future. Ofcourse this override should not touch pm_idle (which would be removed anyway).

cpu_idle()

	if (cpu_idle_call())
		default_idle()

This is also a clean way for CONFIG_CPU_IDLE=n to work.

Quoted 4 lines

Provision is already there to call default_idle from inside cpuidle_idle_call(); we can use that after checking a flag?? Can we use something like boot_option_idle_override? Or set/unset flag through an API?

Quoted 8 lines

Quoted 4 lines
delete pm_idle
x86 will then use default_idle or cpuidle
allow cpuidle to use default_idle to handle the period
where it polls because cpus have not yet registered
If we remove pm_idle and directly call cpuidle, the check already exists to call default_idle until a cpuidle driver (and cpus) is registered.

it isn't working.
If it were, then we'd not see any polling in the cpuidle stats.

cheers,
-Len

Alan Cox

2011-03-31 09:45 UTC #64 lore raw

Re: [PATCH 0/9] x86 idle cruft removal - v2

In reply to Len Brown

Quoted 2 lines

[PATCH 6/9] x86 idle APM: delete apm_cpu_idle(), and its use of pm_idle [PATCH 7/9] x86 idle: do not EXPORT_SYMBOL pm_idle and default_idle

I thought someone had agreed to look after APM ?

I'm also curious why you write

"There is some doubt whether the APM idle feature to call into the BIOS from the idle loop is reliable. Certainly it was known to fail on some machines, but more importantly, APM machines have not shipped for a decade and so finding machines to test the code is problematic."

We don't care if it doesn't work on a few machines (in fact we have a table to avoid that), we care that it *DOES* work on lots.

Removing it probably isn't a bad thing long term, but it's not appeared in the deprecated list and has not been there for several releases so it is not eligible for removal at this point.

People spent years getting Linux to support all this hardware and throwing bits out left right and centre to tidy up your current project is not the way it should be done.

So can we do this properly please. We have a process for good reason.

Deprecate it properly

Add a printk/WARN_ON() indicating to the user it is deprecated but we will continue, and then give it a couple of releaes. Kerneloops.org will help answer whether that WARN_ON was hit.

And in the meantime just progress the rest of the work with it present. If you break APM support by accident doing that then either

a) someone will jump up and down and yell regression - and debug it for you

b) there will be silence because nobody noticed it broke

Alan

Alan Cox

2011-03-31 09:48 UTC #65 lore raw

Re: [PATCH 0/9] x86 idle cruft removal - v2

In reply to Len Brown

Quoted 2 lines

[PATCH 6/9] x86 idle APM: delete apm_cpu_idle(), and its use of pm_idle [PATCH 7/9] x86 idle: do not EXPORT_SYMBOL pm_idle and default_idle

I thought someone had agreed to look after APM ?

I'm also curious why you write

We don't care if it doesn't work on a few machines (in fact we have a table to avoid that), we care that it *DOES* work on lots.

Removing it probably isn't a bad thing long term, but it's not appeared in the deprecated list and has not been there for several releases so it is not eligible for removal at this point.

People spent years getting Linux to support all this hardware and throwing bits out left right and centre to tidy up your current project is not the way it should be done.

So can we do this properly please. We have a process for good reason.

Deprecate it properly

Add a printk/WARN_ON() indicating to the user it is deprecated but we will continue, and then give it a couple of releaes. Kerneloops.org will help answer whether that WARN_ON was hit.

And in the meantime just progress the rest of the work with it present. If you break APM support by accident doing that then either

a) someone will jump up and down and yell regression - and debug it for you

b) there will be silence because nobody noticed it broke

Alan

Ingo Molnar

2011-03-31 10:28 UTC #66 lore raw

Re: [PATCH 0/9] x86 idle cruft removal - v2

Quoted 7 lines · Alan Cox

We don't care if it doesn't work on a few machines (in fact we have a table to avoid that), we care that it *DOES* work on lots.
Removing it probably isn't a bad thing long term, but it's not appeared in the deprecated list and has not been there for several releases so it is not eligible for removal at this point.

Quoted 7 lines

People spent years getting Linux to support all this hardware and throwing bits out left right and centre to tidy up your current project is not the way it should be done.
So can we do this properly please. We have a process for good reason.
Deprecate it properly

Ok, agreed. Len, mind delaying this patch for a few releases?

Quoted 3 lines

Add a printk/WARN_ON() indicating to the user it is deprecated but we will continue, and then give it a couple of releaes. Kerneloops.org will help answer whether that WARN_ON was hit.

Yeah, also add a -stable backport so that older kernel users have a chance to notice faster.

Thanks,

Ingo

Ingo Molnar

2011-03-31 10:28 UTC #67 lore raw

Re: [PATCH 0/9] x86 idle cruft removal - v2

In reply to Alan Cox

Quoted 7 lines · Alan Cox

We don't care if it doesn't work on a few machines (in fact we have a table to avoid that), we care that it *DOES* work on lots.
Removing it probably isn't a bad thing long term, but it's not appeared in the deprecated list and has not been there for several releases so it is not eligible for removal at this point.

Quoted 7 lines

People spent years getting Linux to support all this hardware and throwing bits out left right and centre to tidy up your current project is not the way it should be done.
So can we do this properly please. We have a process for good reason.
Deprecate it properly

Ok, agreed. Len, mind delaying this patch for a few releases?

Quoted 3 lines

Add a printk/WARN_ON() indicating to the user it is deprecated but we will continue, and then give it a couple of releaes. Kerneloops.org will help answer whether that WARN_ON was hit.

Yeah, also add a -stable backport so that older kernel users have a chance to notice faster.

Thanks,

Ingo

Len Brown

author reviewer

2011-04-01 04:24 UTC #68 lore raw

Re: [PATCH 0/9] x86 idle cruft removal - v2

In reply to Len Brown

Thanks for the review feedback that this change is too sudden. How about this plan with a 4-month delay?

cheers,
-Len Brown, Intel Open Source Technology Center

2.6.39-rc1
----------

x86 idle: deprecate floppy disable_hlt

	feature-removal.txt for 2.6.40 (4 months)
	WARN_ONCE on use
	cc: [email protected]

x86 idle APM: deprecate apm_cpu_idle
feature-removal.txt for 2.6.40 (4 months) #warning on CONFIG_APM_CPU_IDLE remove in 2.6.40 WARN_ONCE in apm_cpu_idle()
cc: [email protected]

x86 idle: export pm_idle only for CONFIG_APM_MODULE
like we do for default_idle(), EXPORT_SYMBOL(pm_idle) only on CONFIG_APM_MODULE

x86 idle: deprecate "no-hlt" cmdline param
feature-removal.txt for 2.6.40 (4 months) cc [email protected]
WARN_ONCE if used, ask if idle=poll is sufficient same as idle=poll, except no-hlt also disables
HLT in machine_halt().

x86 idle: deprecate "idle=mwait"

	feature-removal.txt for 2.6.40 (4 months)
	cc [email protected]
	WARN_ONCE on invocation

x86 idle: re-name ce1_idle
rename for clarity, no functional change

2.6.40-merge
------
x86 idle: move mwait_idle_with_hints()
out of process.c to cstate.c, make static

x86 idle floppy: remove deprecated disable_hlt/enable_hlt

x86 idle: delete deprecated idle=mwait
default_idle() can use HLT

cpuidle: add cmdline "cpuidle=off"
allow falling back to native default_idle

x86 idle xen: stop touching pm_idle and default_idle
Xen Dom0 kernel only needs HLT, but include CPU_IDLE, ACPI etc for running on bare hardware. So when running in Xen Dom0 mode, disable cpuidle to fall back to default_idle.

x86 idle APM: remove deprecated apm_cpu_idle()
and its use of pm_idle

x86 idle cpuidle: delete public use of pm_idle

	make pm_idle and default_idle static to process.c
	add return value from cpu_idle_call()
	invoke cpu_idle_call from cpu_idle() rather than via pm_idle

	cpu_idle() {
		...
		if (cpu_idle_call())
			pm_idle();	/* non cpuidle default */
	}

x86 idle: remove "no-hlt" cmdline param
remove deprecated "no-hlt"
use idle=poll instead

x86 idle: remove cpuinfo_x86.hlt_works_ok flag
it became a NOP when "no-hlt" was removed

x86 idle: remove hlt_works()
it became a NOP when cpuinfo_x86.hlt_works_ok was removed

Len Brown

author reviewer

2011-04-01 04:24 UTC #69 lore raw

Re: [PATCH 0/9] x86 idle cruft removal - v2

In reply to Len Brown

Thanks for the review feedback that this change is too sudden. How about this plan with a 4-month delay?

cheers,
-Len Brown, Intel Open Source Technology Center

2.6.39-rc1
----------

x86 idle: deprecate floppy disable_hlt

	feature-removal.txt for 2.6.40 (4 months)
	WARN_ONCE on use
	cc: [email protected]

x86 idle APM: deprecate apm_cpu_idle
feature-removal.txt for 2.6.40 (4 months) #warning on CONFIG_APM_CPU_IDLE remove in 2.6.40 WARN_ONCE in apm_cpu_idle()
cc: [email protected]

x86 idle: export pm_idle only for CONFIG_APM_MODULE
like we do for default_idle(), EXPORT_SYMBOL(pm_idle) only on CONFIG_APM_MODULE

x86 idle: deprecate "idle=mwait"

	feature-removal.txt for 2.6.40 (4 months)
	cc [email protected]
	WARN_ONCE on invocation

x86 idle: re-name ce1_idle
rename for clarity, no functional change

2.6.40-merge
------
x86 idle: move mwait_idle_with_hints()
out of process.c to cstate.c, make static

x86 idle floppy: remove deprecated disable_hlt/enable_hlt

x86 idle: delete deprecated idle=mwait
default_idle() can use HLT

cpuidle: add cmdline "cpuidle=off"
allow falling back to native default_idle

x86 idle APM: remove deprecated apm_cpu_idle()
and its use of pm_idle

x86 idle cpuidle: delete public use of pm_idle

	make pm_idle and default_idle static to process.c
	add return value from cpu_idle_call()
	invoke cpu_idle_call from cpu_idle() rather than via pm_idle

	cpu_idle() {
		...
		if (cpu_idle_call())
			pm_idle();	/* non cpuidle default */
	}

x86 idle: remove "no-hlt" cmdline param
remove deprecated "no-hlt"
use idle=poll instead

x86 idle: remove cpuinfo_x86.hlt_works_ok flag
it became a NOP when "no-hlt" was removed

x86 idle: remove hlt_works()
it became a NOP when cpuinfo_x86.hlt_works_ok was removed

Trinabh Gupta

2011-04-01 09:38 UTC #70 lore raw

Re: [PATCH 0/9] x86 idle cruft removal - v2

Quoted 52 lines

2.6.39-rc1
----------
x86 idle: deprecate floppy disable_hlt
	feature-removal.txt for 2.6.40 (4 months)
	WARN_ONCE on use
	cc: [email protected]
x86 idle APM: deprecate apm_cpu_idle
feature-removal.txt for 2.6.40 (4 months) #warning on CONFIG_APM_CPU_IDLE remove in 2.6.40 WARN_ONCE in apm_cpu_idle()
cc: [email protected]
x86 idle: export pm_idle only for CONFIG_APM_MODULE
like we do for default_idle(), EXPORT_SYMBOL(pm_idle) only on CONFIG_APM_MODULE
x86 idle: deprecate "no-hlt" cmdline param
feature-removal.txt for 2.6.40 (4 months) cc [email protected]
WARN_ONCE if used, ask if idle=poll is sufficient same as idle=poll, except no-hlt also disables
HLT in machine_halt().
x86 idle: deprecate "idle=mwait"
	feature-removal.txt for 2.6.40 (4 months)
	cc [email protected]
	WARN_ONCE on invocation
x86 idle: re-name ce1_idle
rename for clarity, no functional change
2.6.40-merge
------
x86 idle: move mwait_idle_with_hints()
out of process.c to cstate.c, make static
x86 idle floppy: remove deprecated disable_hlt/enable_hlt
x86 idle: delete deprecated idle=mwait
default_idle() can use HLT
cpuidle: add cmdline "cpuidle=off"
allow falling back to native default_idle
x86 idle xen: stop touching pm_idle and default_idle
Xen Dom0 kernel only needs HLT, but include CPU_IDLE, ACPI etc for running on bare hardware. So when running in Xen Dom0 mode, disable cpuidle to fall back to default_idle.

Quoted 5 lines

x86 idle APM: remove deprecated apm_cpu_idle()
and its use of pm_idle
x86 idle cpuidle: delete public use of pm_idle
make pm_idle and default_idle static to process.c

Hi Len,

I guess this would eliminate the problems caused by pm_idle. In that case I also think we need not implement a default driver (like the one I had done https://lkml.org/lkml/2011/3/22/154)
to handle the case when acpi_idle and intel_idle may not register.

Additionally, we may not need to support multiple cpuidle driver registration as now there would be only acpi_idle and intel_idle and mechanism already exists to select between the two.

Thanks,
-Trinabh

Quoted 9 lines

	add return value from cpu_idle_call()
	invoke cpu_idle_call from cpu_idle() rather than via pm_idle

	cpu_idle() {
		...
		if (cpu_idle_call())
			pm_idle();	/* non cpuidle default */
	}

Trinabh Gupta

2011-04-01 09:38 UTC #71 lore raw

Re: [linux-pm] [PATCH 0/9] x86 idle cruft removal - v2

In reply to Len Brown

Quoted 52 lines

2.6.39-rc1
----------
x86 idle: deprecate floppy disable_hlt
	feature-removal.txt for 2.6.40 (4 months)
	WARN_ONCE on use
	cc: [email protected]
x86 idle APM: deprecate apm_cpu_idle
feature-removal.txt for 2.6.40 (4 months) #warning on CONFIG_APM_CPU_IDLE remove in 2.6.40 WARN_ONCE in apm_cpu_idle()
cc: [email protected]
x86 idle: export pm_idle only for CONFIG_APM_MODULE
like we do for default_idle(), EXPORT_SYMBOL(pm_idle) only on CONFIG_APM_MODULE
x86 idle: deprecate "no-hlt" cmdline param
feature-removal.txt for 2.6.40 (4 months) cc [email protected]
WARN_ONCE if used, ask if idle=poll is sufficient same as idle=poll, except no-hlt also disables
HLT in machine_halt().
x86 idle: deprecate "idle=mwait"
	feature-removal.txt for 2.6.40 (4 months)
	cc [email protected]
	WARN_ONCE on invocation
x86 idle: re-name ce1_idle
rename for clarity, no functional change
2.6.40-merge
------
x86 idle: move mwait_idle_with_hints()
out of process.c to cstate.c, make static
x86 idle floppy: remove deprecated disable_hlt/enable_hlt
x86 idle: delete deprecated idle=mwait
default_idle() can use HLT
cpuidle: add cmdline "cpuidle=off"
allow falling back to native default_idle
x86 idle xen: stop touching pm_idle and default_idle
Xen Dom0 kernel only needs HLT, but include CPU_IDLE, ACPI etc for running on bare hardware. So when running in Xen Dom0 mode, disable cpuidle to fall back to default_idle.

Quoted 5 lines

x86 idle APM: remove deprecated apm_cpu_idle()
and its use of pm_idle
x86 idle cpuidle: delete public use of pm_idle
make pm_idle and default_idle static to process.c

Hi Len,

Additionally, we may not need to support multiple cpuidle driver registration as now there would be only acpi_idle and intel_idle and mechanism already exists to select between the two.

Thanks,
-Trinabh

Quoted 9 lines

	add return value from cpu_idle_call()
	invoke cpu_idle_call from cpu_idle() rather than via pm_idle

	cpu_idle() {
		...
		if (cpu_idle_call())
			pm_idle();	/* non cpuidle default */
	}

Len Brown

author reviewer

2011-04-01 18:33 UTC #72 lore raw

Re: [PATCH 0/9] x86 idle cruft removal - v2

Quoted 2 lines

I guess this would eliminate the problems caused by pm_idle.

Right.

...at least we can contain it inside process.c where we still need to be able to handle halt/amd-bug/poll. Probably I'll re-name it to better reflect its function, say x86_default_idle, in this case.

Quoted 3 lines

In that case I also think we need not implement a default driver (like the one I had done https://lkml.org/lkml/2011/3/22/154)
to handle the case when acpi_idle and intel_idle may not register.

Right.

the stuff in process.c should handle the !cpuidle and !CPU_IDLE cases, and in the typical case it will handle idle during boot before cpuidle initializes.

Quoted 3 lines

Additionally, we may not need to support multiple cpuidle driver registration as now there would be only acpi_idle and intel_idle
and mechanism already exists to select between the two.

Right.

I think multiple driver registration is over-kill, though I have no real opposition to it should a real need for it emerge. The only need I could come up with is that it would save me a reboot when I want to compare drivers -- but we should optimize for real-world-use, not lab use, and simpler is better.

thanks,
Len Brown, Intel Open Source Technology Center

Len Brown

author reviewer

2011-04-01 18:33 UTC #73 lore raw

Re: [linux-pm] [PATCH 0/9] x86 idle cruft removal - v2

In reply to Trinabh Gupta

Quoted 2 lines

I guess this would eliminate the problems caused by pm_idle.

Right.

Quoted 3 lines

In that case I also think we need not implement a default driver (like the one I had done https://lkml.org/lkml/2011/3/22/154)
to handle the case when acpi_idle and intel_idle may not register.

Right.

the stuff in process.c should handle the !cpuidle and !CPU_IDLE cases, and in the typical case it will handle idle during boot before cpuidle initializes.

Quoted 3 lines

Additionally, we may not need to support multiple cpuidle driver registration as now there would be only acpi_idle and intel_idle
and mechanism already exists to select between the two.

Right.

thanks,
Len Brown, Intel Open Source Technology Center

Len Brown

author reviewer

2011-04-02 06:22 UTC #74 lore raw

idle cleanup - v3

In reply to Len Brown

Thanks for the reviews, tests & Acks -- keep 'em coming!

By the end of this series, pm_idle is removed as a public x86 idle-loop registration mechanism. A few other things are cleaned up in the process.

thanks,
Len Brown - Intel Open Source Technology Center

The first 11 are staged here:
git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-idle-2.6.git idle-release I would like to see it make 2.6.39, and some for .stable

[PATCH 01/18] cpuidle: menu: fixed wrapping timers at 4.294 seconds [PATCH 02/18] x86 idle floppy: deprecate disable_hlt()
[PATCH 03/18] x86 idle APM: deprecate CONFIG_APM_CPU_IDLE [PATCH 04/18] x86 idle: EXPORT_SYMBOL(default_idle, pm_idle) only [PATCH 05/18] x86 idle: deprecate "no-hlt" cmdline param [PATCH 06/18] x86 idle: deprecate mwait_idle() and "idle=mwait" [PATCH 07/18] x86 idle: clarify AMD erratum 400 workaround [PATCH 08/18] cpuidle: create bootparam "cpuidle.off=1" [PATCH 09/18] cpuidle: replace xen access to x86 pm_idle and default_idle [PATCH 10/18] x86 idle: move mwait_idle_with_hints() to where it is used [PATCH 11/18] cpuidle: stop using pm_idle

 Documentation/feature-removal-schedule.txt |   36 +++++++++++++++
 Documentation/kernel-parameters.txt        |    3 +
 arch/arm/kernel/process.c                  |    4 +-
 arch/sh/kernel/idle.c                      |    6 ++-
 arch/x86/include/asm/acpi.h                |    2 +-
 arch/x86/include/asm/idle.h                |    2 +-
 arch/x86/include/asm/processor.h           |    6 +--
 arch/x86/kernel/acpi/cstate.c              |   24 ++++++++++
 arch/x86/kernel/apm_32.c                   |    2 +
 arch/x86/kernel/cpu/bugs.c                 |    1 +
 arch/x86/kernel/cpu/common.c               |    2 +-
 arch/x86/kernel/process.c                  |   66 ++++++++++------------------
 arch/x86/kernel/process_32.c               |    4 +-
 arch/x86/kernel/process_64.c               |    4 +-
 arch/x86/kernel/smpboot.c                  |    2 +-
 arch/x86/xen/setup.c                       |    3 +-
 drivers/acpi/processor_idle.c              |    2 +-
 drivers/block/floppy.c                     |    1 +
 drivers/cpuidle/cpuidle.c                  |   50 +++++++++++++--------
 drivers/cpuidle/cpuidle.h                  |    1 +
 drivers/cpuidle/driver.c                   |    3 +
 drivers/cpuidle/governor.c                 |    3 +
 drivers/cpuidle/governors/menu.c           |    4 +-
 include/linux/cpuidle.h                    |    4 ++
 24 files changed, 157 insertions(+), 78 deletions(-)

The rest are staged here:
git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-idle-2.6.git idle-test which is a super-set of the above. These will wait for 2.6.40.

[PATCH 12/18] 2.6.40: x86 idle: remove deprecated "no-hlt" cmdline [PATCH 13/18] 2.6.40: x86 idle: remove deprecated "hlt_bug: no" in [PATCH 14/18] 2.6.40: x86 idle floppy: remove deprecated disalbe_hlt [PATCH 15/18] 2.6.40: x86 idle: remove deprecated hlt_use_halt() [PATCH 16/18] 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle() [PATCH 17/18] 2.6.40: x86 idle: do not export default_idle() and [PATCH 18/18] 2.6.40: x86 idle: remove deprecated mwait_idle()

 Documentation/feature-removal-schedule.txt |   36 -----
 Documentation/kernel-parameters.txt        |   11 +--
 arch/x86/Kconfig                           |   11 --
 arch/x86/include/asm/processor.h           |   12 +--
 arch/x86/include/asm/system.h              |    9 -
 arch/x86/kernel/apm_32.c                   |  234 ----------------------------
 arch/x86/kernel/cpu/bugs.c                 |   14 +--
 arch/x86/kernel/cpu/proc.c                 |    2 -
 arch/x86/kernel/process.c                  |  109 ++-----------
 arch/x86/kernel/setup.c                    |    4 +-
 arch/x86/xen/setup.c                       |    3 -
 drivers/acpi/processor_idle.c              |    1 -
 drivers/block/floppy.c                     |   36 -----
 13 files changed, 22 insertions(+), 460 deletions(-)

Len Brown

author reviewer

2011-04-02 06:23 UTC #75 lore raw

idle cleanup - v3

In reply to Len Brown

Thanks for the reviews, tests & Acks -- keep 'em coming!

By the end of this series, pm_idle is removed as a public x86 idle-loop registration mechanism. A few other things are cleaned up in the process.

thanks,
Len Brown - Intel Open Source Technology Center

The first 11 are staged here:
git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-idle-2.6.git idle-release I would like to see it make 2.6.39, and some for .stable

 Documentation/feature-removal-schedule.txt |   36 +++++++++++++++
 Documentation/kernel-parameters.txt        |    3 +
 arch/arm/kernel/process.c                  |    4 +-
 arch/sh/kernel/idle.c                      |    6 ++-
 arch/x86/include/asm/acpi.h                |    2 +-
 arch/x86/include/asm/idle.h                |    2 +-
 arch/x86/include/asm/processor.h           |    6 +--
 arch/x86/kernel/acpi/cstate.c              |   24 ++++++++++
 arch/x86/kernel/apm_32.c                   |    2 +
 arch/x86/kernel/cpu/bugs.c                 |    1 +
 arch/x86/kernel/cpu/common.c               |    2 +-
 arch/x86/kernel/process.c                  |   66 ++++++++++------------------
 arch/x86/kernel/process_32.c               |    4 +-
 arch/x86/kernel/process_64.c               |    4 +-
 arch/x86/kernel/smpboot.c                  |    2 +-
 arch/x86/xen/setup.c                       |    3 +-
 drivers/acpi/processor_idle.c              |    2 +-
 drivers/block/floppy.c                     |    1 +
 drivers/cpuidle/cpuidle.c                  |   50 +++++++++++++--------
 drivers/cpuidle/cpuidle.h                  |    1 +
 drivers/cpuidle/driver.c                   |    3 +
 drivers/cpuidle/governor.c                 |    3 +
 drivers/cpuidle/governors/menu.c           |    4 +-
 include/linux/cpuidle.h                    |    4 ++
 24 files changed, 157 insertions(+), 78 deletions(-)

The rest are staged here:
git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-idle-2.6.git idle-test which is a super-set of the above. These will wait for 2.6.40.

 Documentation/feature-removal-schedule.txt |   36 -----
 Documentation/kernel-parameters.txt        |   11 +--
 arch/x86/Kconfig                           |   11 --
 arch/x86/include/asm/processor.h           |   12 +--
 arch/x86/include/asm/system.h              |    9 -
 arch/x86/kernel/apm_32.c                   |  234 ----------------------------
 arch/x86/kernel/cpu/bugs.c                 |   14 +--
 arch/x86/kernel/cpu/proc.c                 |    2 -
 arch/x86/kernel/process.c                  |  109 ++-----------
 arch/x86/kernel/setup.c                    |    4 +-
 arch/x86/xen/setup.c                       |    3 -
 drivers/acpi/processor_idle.c              |    1 -
 drivers/block/floppy.c                     |   36 -----
 13 files changed, 22 insertions(+), 460 deletions(-)

Len Brown

author reviewer

2011-04-02 06:22 UTC #76 lore raw

PATCH 1/18 cpuidle: menu: fixed wrapping timers at 4.294 seconds

From: Tero Kristo <[email protected]>

Cpuidle menu governor is using u32 as a temporary datatype for storing nanosecond values which wrap around at 4.294 seconds. This causes errors in predicted sleep times resulting in higher than should be C state selection and increased power consumption. This also breaks cpuidle state residency statistics.

cc [email protected]

Signed-off-by Tero Kristo <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 drivers/cpuidle/governors/menu.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

drivers/cpuidle/governors/menu.c +3 -1

index f508690..c47f3d0 100644
@@ -237,6 +237,7 @@ static int menu_select(struct cpuidle_device *dev)
 	unsigned int power_usage = -1;
 	int i;
 	int multiplier;
+	struct timespec t;
 
 	if (data->needs_update) {
 		menu_update(dev);

@@ -251,8 +252,9 @@ static int menu_select(struct cpuidle_device *dev)
 		return 0;
 
 	/* determine the expected residency time, round up */
+	t = ktime_to_timespec(tick_nohz_get_sleep_length());
 	data->expected_us =
-	    DIV_ROUND_UP((u32)ktime_to_ns(tick_nohz_get_sleep_length()), 1000);
+		t.tv_sec * USEC_PER_SEC + t.tv_nsec / NSEC_PER_USEC;
 
 
 	data->bucket = which_bucket(data->expected_us);

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:23 UTC #77 lore raw

PATCH 1/18 cpuidle: menu: fixed wrapping timers at 4.294 seconds

In reply to Len Brown

From: Tero Kristo <[email protected]>

cc [email protected]

Signed-off-by Tero Kristo <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 drivers/cpuidle/governors/menu.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

drivers/cpuidle/governors/menu.c +3 -1

index f508690..c47f3d0 100644
@@ -237,6 +237,7 @@ static int menu_select(struct cpuidle_device *dev)
 	unsigned int power_usage = -1;
 	int i;
 	int multiplier;
+	struct timespec t;
 
 	if (data->needs_update) {
 		menu_update(dev);

@@ -251,8 +252,9 @@ static int menu_select(struct cpuidle_device *dev)
 		return 0;
 
 	/* determine the expected residency time, round up */
+	t = ktime_to_timespec(tick_nohz_get_sleep_length());
 	data->expected_us =
-	    DIV_ROUND_UP((u32)ktime_to_ns(tick_nohz_get_sleep_length()), 1000);
+		t.tv_sec * USEC_PER_SEC + t.tv_nsec / NSEC_PER_USEC;
 
 
 	data->bucket = which_bucket(data->expected_us);

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:22 UTC #78 lore raw

PATCH 2/18 x86 idle floppy: deprecate disable_hlt()

In reply to Len Brown

From: Len Brown <[email protected]>

Plan to remove floppy_disable_hlt in 2.6.40, an ancient workaround with comments that it should be removed.

This allows us to remove clutter and a run-time branch from the idle code.

WARN_ONCE() on invocation until it is removed.

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |    8 ++++++++
 drivers/block/floppy.c                     |    1 +
 2 files changed, 9 insertions(+), 0 deletions(-)

Documentation/feature-removal-schedule.txt +8 -0

index b3f35e5..54db467 100644
@@ -6,6 +6,14 @@ be removed from this file.
 
 ---------------------------
 
+What:	x86 floppy disable_hlt
+When:	2.6.40
+Why:	ancient workaround of dubious utility clutters the
+	code used by everybody else.
+Who:	Len Brown <[email protected]>
+
+---------------------------
+
 What:	PRISM54
 When:	2.6.34

drivers/block/floppy.c +1 -0

index 77fc76f..41ea03f 100644
@@ -1038,6 +1038,7 @@ static void floppy_disable_hlt(void)
 {
 	unsigned long flags;
 
+	WARN_ONCE(1, "floppy_disable_hlt() scheduled for removal in 2.6.40");
 	spin_lock_irqsave(&floppy_hlt_lock, flags);
 	if (!hlt_disabled) {
 		hlt_disabled = 1;

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:22 UTC #79 lore raw

PATCH 3/18 x86 idle APM: deprecate CONFIG_APM_CPU_IDLE

In reply to Len Brown

From: Len Brown <[email protected]>

We don't want to export the pm_idle function pointer to modules. Currently CONFIG_APM_CPU_IDLE w/ CONFIG_APM_MODULE forces us to.

CONFIG_APM_CPU_IDLE is of dubious value, it runs only on 32-bit uniprocessor laptops that are over 10 years old. It calls into the BIOS during idle, and is known to cause a number of machines to fail.

Removing CONFIG_APM_CPU_IDLE and will allow us to stop exporting pm_idle. Any systems that were calling into the APM BIOS at run-time will simply use HLT instead.

cc [email protected]

cc Jiri Kosina <[email protected]>

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |   10 ++++++++++
 arch/x86/kernel/apm_32.c                   |    2 ++
 2 files changed, 12 insertions(+), 0 deletions(-)

Documentation/feature-removal-schedule.txt +10 -0

index 54db467..bab1acb 100644
@@ -14,6 +14,16 @@ Who:	Len Brown <[email protected]>
 
 ---------------------------
 
+What:	CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
+When:	2.6.40
+Why:	This optional sub-feature of APM is of dubious reliability,
+	and ancient APM laptops are likely better served by calling HLT.
+	Deleting CONFIG_APM_CPU_IDLE allows x86 to stop exporting
+	the pm_idle function pointer to modules.
+Who:	Len Brown <[email protected]>
+
+----------------------------
+
 What:	PRISM54
 When:	2.6.34

arch/x86/kernel/apm_32.c +2 -0

index 0e4f24c..072546c 100644
@@ -359,6 +359,7 @@ struct apm_user {
  * idle percentage above which bios idle calls are done
  */
 #ifdef CONFIG_APM_CPU_IDLE
+#warning deprecated CONFIG_APM_CPU_IDLE will be deleted in 2.6.40
 #define DEFAULT_IDLE_THRESHOLD	95
 #else
 #define DEFAULT_IDLE_THRESHOLD	100

@@ -902,6 +903,7 @@ static void apm_cpu_idle(void)
 	unsigned int jiffies_since_last_check = jiffies - last_jiffies;
 	unsigned int bucket;
 
+	WARN_ONCE(1, "deprecated apm_cpu_idle will be deleted in 2.6.40");
 recalc:
 	if (jiffies_since_last_check > IDLE_CALC_LIMIT) {
 		use_apm_idle = 0;

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:23 UTC #80 lore raw

PATCH 3/18 x86 idle APM: deprecate CONFIG_APM_CPU_IDLE

In reply to Len Brown

From: Len Brown <[email protected]>

We don't want to export the pm_idle function pointer to modules. Currently CONFIG_APM_CPU_IDLE w/ CONFIG_APM_MODULE forces us to.

Removing CONFIG_APM_CPU_IDLE and will allow us to stop exporting pm_idle. Any systems that were calling into the APM BIOS at run-time will simply use HLT instead.

cc [email protected]

cc Jiri Kosina <[email protected]>

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |   10 ++++++++++
 arch/x86/kernel/apm_32.c                   |    2 ++
 2 files changed, 12 insertions(+), 0 deletions(-)

Documentation/feature-removal-schedule.txt +10 -0

index 54db467..bab1acb 100644
@@ -14,6 +14,16 @@ Who:	Len Brown <[email protected]>
 
 ---------------------------
 
+What:	CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
+When:	2.6.40
+Why:	This optional sub-feature of APM is of dubious reliability,
+	and ancient APM laptops are likely better served by calling HLT.
+	Deleting CONFIG_APM_CPU_IDLE allows x86 to stop exporting
+	the pm_idle function pointer to modules.
+Who:	Len Brown <[email protected]>
+
+----------------------------
+
 What:	PRISM54
 When:	2.6.34

arch/x86/kernel/apm_32.c +2 -0

index 0e4f24c..072546c 100644
@@ -359,6 +359,7 @@ struct apm_user {
  * idle percentage above which bios idle calls are done
  */
 #ifdef CONFIG_APM_CPU_IDLE
+#warning deprecated CONFIG_APM_CPU_IDLE will be deleted in 2.6.40
 #define DEFAULT_IDLE_THRESHOLD	95
 #else
 #define DEFAULT_IDLE_THRESHOLD	100

@@ -902,6 +903,7 @@ static void apm_cpu_idle(void)
 	unsigned int jiffies_since_last_check = jiffies - last_jiffies;
 	unsigned int bucket;
 
+	WARN_ONCE(1, "deprecated apm_cpu_idle will be deleted in 2.6.40");
 recalc:
 	if (jiffies_since_last_check > IDLE_CALC_LIMIT) {
 		use_apm_idle = 0;

Signature · 1 line

1.7.5.rc0

Alan Cox

2011-04-02 11:27 UTC #81 lore raw

Re: [PATCH 03/18] x86 idle APM: deprecate CONFIG_APM_CPU_IDLE

Quoted 2 lines

We don't want to export the pm_idle function pointer to modules. Currently CONFIG_APM_CPU_IDLE w/ CONFIG_APM_MODULE forces us to.

So you could jsut compile it in ...

Quoted 4 lines

CONFIG_APM_CPU_IDLE is of dubious value, it runs only on 32-bit uniprocessor laptops that are over 10 years old. It calls into the BIOS during idle, and is known to cause a number of machines to fail.

It also works on lots of desktops from that era, more of which are still around.

Quoted 4 lines

Removing CONFIG_APM_CPU_IDLE and will allow us to stop exporting pm_idle. Any systems that were calling into the APM BIOS at run-time will simply use HLT instead.

(which is btw what quite a few later APM implementations seem to do ;))

Documentation/feature-removal-schedule.txt Who: Len Brown <[email protected]> · line 18

Quoted 2 lines

Documentation/feature-removal-schedule.txt +2 -0
+What:	CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
+When:	2.6.40

One release isn't enough time - it won't propagate out - you keep rushing, hurrying and pushing at this trying to do it fast.

Why - its a sigle symbol export of minor ugliness, it doesn't justify the amount of hatred you are expending upon it.

Give it a year, it doesn't cause any complexities I can see.

Len Brown

author reviewer

2011-04-02 18:28 UTC #82 lore raw

Re: [PATCH 03/18] x86 idle APM: deprecate CONFIG_APM_CPU_IDLE

Quoted 1 line

Give it a year, it doesn't cause any complexities I can see.

I'd rather not create a new an APM cpuilde driver, since there is nobody volunteering to test it. If you have the time and the hardware, please speak up.

thanks,
-Len Brown, Intel Open Source Technolgy Center

Len Brown

author reviewer

2011-04-02 18:28 UTC #83 lore raw

Re: [PATCH 03/18] x86 idle APM: deprecate CONFIG_APM_CPU_IDLE

In reply to Alan Cox

Quoted 1 line

Give it a year, it doesn't cause any complexities I can see.

I'd rather not create a new an APM cpuilde driver, since there is nobody volunteering to test it. If you have the time and the hardware, please speak up.

thanks,
-Len Brown, Intel Open Source Technolgy Center

Alan Cox

2011-04-02 19:43 UTC #84 lore raw

Re: [PATCH 03/18] x86 idle APM: deprecate CONFIG_APM_CPU_IDLE

Quoted 3 lines · On Sat, 02 Apr 2011 14:28:31 -0400 (EDT) Len Brown <[email protected]> wrote:

Quoted 1 line
Give it a year, it doesn't cause any complexities I can see.
I'd rather not create a new an APM cpuilde driver

In which case don't remove the existing one - as far as bugzilla shows it seems to be working fine.

Alan Cox

2011-04-02 19:44 UTC #85 lore raw

Re: [PATCH 03/18] x86 idle APM: deprecate CONFIG_APM_CPU_IDLE

In reply to Len Brown

Quoted 3 lines · On Sat, 02 Apr 2011 14:28:31 -0400 (EDT) Len Brown <[email protected]> wrote:

Quoted 1 line
Give it a year, it doesn't cause any complexities I can see.
I'd rather not create a new an APM cpuilde driver

In which case don't remove the existing one - as far as bugzilla shows it seems to be working fine.

Pavel Machek

2011-04-08 06:22 UTC #86 lore raw

Re: [PATCH 03/18] x86 idle APM: deprecate CONFIG_APM_CPU_IDLE

In reply to Len Brown

Quoted 5 lines · Len Brown

Quoted 1 line
Give it a year, it doesn't cause any complexities I can see.
I'd rather not create a new an APM cpuilde driver, since there is nobody volunteering to test it. If you have the time and the hardware, please speak up.

I'm willing to test is, as is Jiri Kosina AFAICT.
Pavel

Signature · 2 lines

(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Pavel Machek

2011-04-08 06:23 UTC #87 lore raw

Re: [PATCH 03/18] x86 idle APM: deprecate CONFIG_APM_CPU_IDLE

In reply to Len Brown

Quoted 5 lines · Len Brown

Quoted 1 line
Give it a year, it doesn't cause any complexities I can see.
I'd rather not create a new an APM cpuilde driver, since there is nobody volunteering to test it. If you have the time and the hardware, please speak up.

I'm willing to test is, as is Jiri Kosina AFAICT.
Pavel

Signature · 2 lines

(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Alan Cox

2011-04-02 11:28 UTC #88 lore raw

Re: [PATCH 03/18] x86 idle APM: deprecate CONFIG_APM_CPU_IDLE

In reply to Len Brown

Quoted 2 lines

We don't want to export the pm_idle function pointer to modules. Currently CONFIG_APM_CPU_IDLE w/ CONFIG_APM_MODULE forces us to.

So you could jsut compile it in ...

Quoted 4 lines

CONFIG_APM_CPU_IDLE is of dubious value, it runs only on 32-bit uniprocessor laptops that are over 10 years old. It calls into the BIOS during idle, and is known to cause a number of machines to fail.

It also works on lots of desktops from that era, more of which are still around.

Quoted 4 lines

Removing CONFIG_APM_CPU_IDLE and will allow us to stop exporting pm_idle. Any systems that were calling into the APM BIOS at run-time will simply use HLT instead.

(which is btw what quite a few later APM implementations seem to do ;))

Documentation/feature-removal-schedule.txt Who: Len Brown <[email protected]> · line 18

Quoted 2 lines

Documentation/feature-removal-schedule.txt +2 -0
+What:	CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
+When:	2.6.40

One release isn't enough time - it won't propagate out - you keep rushing, hurrying and pushing at this trying to do it fast.

Why - its a sigle symbol export of minor ugliness, it doesn't justify the amount of hatred you are expending upon it.

Give it a year, it doesn't cause any complexities I can see.

Len Brown

author reviewer

2011-04-02 06:22 UTC #89 lore raw

PATCH 4/18 x86 idle: EXPORT_SYMBOL(default_idle, pm_idle) only when APM demands it

In reply to Len Brown

From: Len Brown <[email protected]>

In the long run, we don't want default_idle() or (pm_idle)() to be exported outside of process.c. Start by not exporting them to modules, unless the APM build demands it.

cc [email protected]

cc Jiri Kosina <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/kernel/process.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

arch/x86/kernel/process.c +3 -1

index ff45541..17b8771 100644
@@ -340,7 +340,9 @@ EXPORT_SYMBOL(boot_option_idle_override);
  * Powermanagement idle function, if any..
  */
 void (*pm_idle)(void);
+#if defined(CONFIG_APM_MODULE) && defined(CONFIG_APM_CPU_IDLE)
 EXPORT_SYMBOL(pm_idle);
+#endif
 
 #ifdef CONFIG_X86_32
 /*

@@ -400,7 +402,7 @@ void default_idle(void)
 		cpu_relax();
 	}
 }
-#ifdef CONFIG_APM_MODULE
+#if defined(CONFIG_APM_MODULE) && defined(CONFIG_APM_CPU_IDLE)
 EXPORT_SYMBOL(default_idle);
 #endif

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:23 UTC #90 lore raw

PATCH 4/18 x86 idle: EXPORT_SYMBOL(default_idle, pm_idle) only when APM demands it

In reply to Len Brown

From: Len Brown <[email protected]>

In the long run, we don't want default_idle() or (pm_idle)() to be exported outside of process.c. Start by not exporting them to modules, unless the APM build demands it.

cc [email protected]

cc Jiri Kosina <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/kernel/process.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

arch/x86/kernel/process.c +3 -1

index ff45541..17b8771 100644
@@ -340,7 +340,9 @@ EXPORT_SYMBOL(boot_option_idle_override);
  * Powermanagement idle function, if any..
  */
 void (*pm_idle)(void);
+#if defined(CONFIG_APM_MODULE) && defined(CONFIG_APM_CPU_IDLE)
 EXPORT_SYMBOL(pm_idle);
+#endif
 
 #ifdef CONFIG_X86_32
 /*

@@ -400,7 +402,7 @@ void default_idle(void)
 		cpu_relax();
 	}
 }
-#ifdef CONFIG_APM_MODULE
+#if defined(CONFIG_APM_MODULE) && defined(CONFIG_APM_CPU_IDLE)
 EXPORT_SYMBOL(default_idle);
 #endif

Signature · 1 line

1.7.5.rc0

Alan Cox

2011-04-02 11:28 UTC #91 lore raw

Re: [PATCH 04/18] x86 idle: EXPORT_SYMBOL(default_idle, pm_idle) only when APM demands it

Quoted 5 lines · On Sat, 02 Apr 2011 02:22:46 -0400 Len Brown <[email protected]> wrote:

From: Len Brown <[email protected]>
In the long run, we don't want default_idle() or (pm_idle)() to be exported outside of process.c. Start by not exporting them to modules, unless the APM build demands it.

Pointless added complexity. Why are you so determined to minimise this - it makes no odds to anyone.

Trinabh Gupta

2011-04-02 12:21 UTC #92 lore raw

Re: [PATCH 04/18] x86 idle: EXPORT_SYMBOL(default_idle, pm_idle) only when APM demands it

Quoted 11 lines · Alan Cox

Quoted 5 lines · On Sat, 02 Apr 2011 02:22:46 -0400 Len Brown<[email protected]> wrote:
From: Len Brown<[email protected]>
In the long run, we don't want default_idle() or (pm_idle)() to be exported outside of process.c. Start by not exporting them to modules, unless the APM build demands it.
Pointless added complexity. Why are you so determined to minimise this - it makes no odds to anyone.

Hi Alan,

I am not sure if I have understood you correctly but I think one problem is that modules such as APM
save the value of pm_idle pointer, set it and restore it back.

At module init:

original_pm_idle = pm_idle;
pm_idle = apm_cpu_idle;

At module exit:

pm_idle = original_pm_idle;

There is no guarantee that the pointer stored is still valid. I think people have problem with such usage; see http://lkml.org/lkml/2009/8/28/50

Thanks,
-Trinabh

Trinabh Gupta

2011-04-02 12:22 UTC #93 lore raw

Re: [linux-pm] [PATCH 04/18] x86 idle: EXPORT_SYMBOL(default_idle, pm_idle) only when APM demands it

In reply to Alan Cox

Quoted 11 lines · Alan Cox

Quoted 5 lines · On Sat, 02 Apr 2011 02:22:46 -0400 Len Brown<[email protected]> wrote:
From: Len Brown<[email protected]>
In the long run, we don't want default_idle() or (pm_idle)() to be exported outside of process.c. Start by not exporting them to modules, unless the APM build demands it.
Pointless added complexity. Why are you so determined to minimise this - it makes no odds to anyone.

Hi Alan,

I am not sure if I have understood you correctly but I think one problem is that modules such as APM
save the value of pm_idle pointer, set it and restore it back.

At module init:

original_pm_idle = pm_idle;
pm_idle = apm_cpu_idle;

At module exit:

pm_idle = original_pm_idle;

There is no guarantee that the pointer stored is still valid. I think people have problem with such usage; see http://lkml.org/lkml/2009/8/28/50

Thanks,
-Trinabh

Alan Cox

2011-04-02 11:28 UTC #94 lore raw

Re: [PATCH 04/18] x86 idle: EXPORT_SYMBOL(default_idle, pm_idle) only when APM demands it

In reply to Len Brown

Quoted 5 lines · On Sat, 02 Apr 2011 02:22:46 -0400 Len Brown <[email protected]> wrote:

From: Len Brown <[email protected]>
In the long run, we don't want default_idle() or (pm_idle)() to be exported outside of process.c. Start by not exporting them to modules, unless the APM build demands it.

Pointless added complexity. Why are you so determined to minimise this - it makes no odds to anyone.

Len Brown

author reviewer

2011-04-02 06:22 UTC #95 lore raw

PATCH 5/18 x86 idle: deprecate "no-hlt" cmdline param

In reply to Len Brown

From: Len Brown <[email protected]>

We'd rather that modern machines not check if HLT works on every entry into idle, for the benefit of machines that had marginal electricals 15-years ago. If those machines are still running the upstream kernel, they can use "idle=poll". The only difference will be that they'll now invoke HLT in machine_hlt().

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |   11 +++++++++++
 arch/x86/kernel/cpu/bugs.c                 |    1 +
 2 files changed, 12 insertions(+), 0 deletions(-)

Documentation/feature-removal-schedule.txt +11 -0

index bab1acb..f587159 100644
@@ -24,6 +24,17 @@ Who:	Len Brown <[email protected]>
 
 ----------------------------
 
+What:	x86_32 "no-hlt" cmdline param
+When:	2.6.40
+Why:	remove a branch from idle path, simplify code used by everybody.
+	This option disabled the use of HLT in idle and machine_halt()
+	for hardware that was flakey 15-years ago.  Today we have
+	"idle=poll" that removed HLT from idle, and so if such a machine
+	is still running the upstream kernel, "idle=poll" is likely sufficient.
+Who:	Len Brown <[email protected]>
+
+----------------------------
+
 What:	PRISM54
 When:	2.6.34

arch/x86/kernel/cpu/bugs.c +1 -0

index c39576c..525514c 100644
@@ -19,6 +19,7 @@
 
 static int __init no_halt(char *s)
 {
+	WARN_ONCE(1, "\"no-hlt\" is deprecated, please use \"idle=poll\"\n");
 	boot_cpu_data.hlt_works_ok = 0;
 	return 1;
 }

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:23 UTC #96 lore raw

PATCH 5/18 x86 idle: deprecate "no-hlt" cmdline param

In reply to Len Brown

From: Len Brown <[email protected]>

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |   11 +++++++++++
 arch/x86/kernel/cpu/bugs.c                 |    1 +
 2 files changed, 12 insertions(+), 0 deletions(-)

Documentation/feature-removal-schedule.txt +11 -0

index bab1acb..f587159 100644
@@ -24,6 +24,17 @@ Who:	Len Brown <[email protected]>
 
 ----------------------------
 
+What:	x86_32 "no-hlt" cmdline param
+When:	2.6.40
+Why:	remove a branch from idle path, simplify code used by everybody.
+	This option disabled the use of HLT in idle and machine_halt()
+	for hardware that was flakey 15-years ago.  Today we have
+	"idle=poll" that removed HLT from idle, and so if such a machine
+	is still running the upstream kernel, "idle=poll" is likely sufficient.
+Who:	Len Brown <[email protected]>
+
+----------------------------
+
 What:	PRISM54
 When:	2.6.34

arch/x86/kernel/cpu/bugs.c +1 -0

index c39576c..525514c 100644
@@ -19,6 +19,7 @@
 
 static int __init no_halt(char *s)
 {
+	WARN_ONCE(1, "\"no-hlt\" is deprecated, please use \"idle=poll\"\n");
 	boot_cpu_data.hlt_works_ok = 0;
 	return 1;
 }

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:22 UTC #97 lore raw

PATCH 6/18 x86 idle: deprecate mwait_idle() and "idle=mwait" cmdline param

In reply to Len Brown

From: Len Brown <[email protected]>

mwait_idle() is a C1-only idle loop intended to be more efficient than HLT on SMP hardware that supports it.

But mwait_idle() has been replaced by the more general mwait_idle_with_hints(), which handles both C1 and deeper C-states. ACPI uses only mwait_idle_with_hints(), and never uses mwait_idle().

Deprecate mwait_idle() and the "idle=mwait" cmdline param to simplify the x86 idle code.

After this change, kernels configured with (!CONFIG_ACPI=n && !CONFIG_INTEL_IDLE=n) when run on hardware that support MWAIT will simply use HLT. If MWAIT is desired on those systems, cpuidle and the cpuidle drivers above will support it.

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |    7 +++++++
 arch/x86/kernel/process.c                  |    1 +
 2 files changed, 8 insertions(+), 0 deletions(-)

Documentation/feature-removal-schedule.txt +7 -0

index f587159..9ee4a2c 100644
@@ -35,6 +35,13 @@ Who:	Len Brown <[email protected]>
 
 ----------------------------
 
+What:	x86 "idle=mwait" cmdline param
+When:	2.6.40
+Why:	simplify x86 idle code
+Who:	Len Brown <[email protected]>
+
+----------------------------
+
 What:	PRISM54
 When:	2.6.34

arch/x86/kernel/process.c +1 -0

index 17b8771..1f64501 100644
@@ -645,6 +645,7 @@ static int __init idle_setup(char *str)
 		boot_option_idle_override = IDLE_POLL;
 	} else if (!strcmp(str, "mwait")) {
 		boot_option_idle_override = IDLE_FORCE_MWAIT;
+		WARN_ONCE(1, "\idle=mwait\" will be removed in 2.6.40\"\n");
 	} else if (!strcmp(str, "halt")) {
 		/*
 		 * When the boot option of idle=halt is added, halt is

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:23 UTC #98 lore raw

PATCH 6/18 x86 idle: deprecate mwait_idle() and "idle=mwait" cmdline param

In reply to Len Brown

From: Len Brown <[email protected]>

mwait_idle() is a C1-only idle loop intended to be more efficient than HLT on SMP hardware that supports it.

But mwait_idle() has been replaced by the more general mwait_idle_with_hints(), which handles both C1 and deeper C-states. ACPI uses only mwait_idle_with_hints(), and never uses mwait_idle().

Deprecate mwait_idle() and the "idle=mwait" cmdline param to simplify the x86 idle code.

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |    7 +++++++
 arch/x86/kernel/process.c                  |    1 +
 2 files changed, 8 insertions(+), 0 deletions(-)

Documentation/feature-removal-schedule.txt +7 -0

index f587159..9ee4a2c 100644
@@ -35,6 +35,13 @@ Who:	Len Brown <[email protected]>
 
 ----------------------------
 
+What:	x86 "idle=mwait" cmdline param
+When:	2.6.40
+Why:	simplify x86 idle code
+Who:	Len Brown <[email protected]>
+
+----------------------------
+
 What:	PRISM54
 When:	2.6.34

arch/x86/kernel/process.c +1 -0

index 17b8771..1f64501 100644
@@ -645,6 +645,7 @@ static int __init idle_setup(char *str)
 		boot_option_idle_override = IDLE_POLL;
 	} else if (!strcmp(str, "mwait")) {
 		boot_option_idle_override = IDLE_FORCE_MWAIT;
+		WARN_ONCE(1, "\idle=mwait\" will be removed in 2.6.40\"\n");
 	} else if (!strcmp(str, "halt")) {
 		/*
 		 * When the boot option of idle=halt is added, halt is

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:22 UTC #99 lore raw

PATCH 7/18 x86 idle: clarify AMD erratum 400 workaround

In reply to Len Brown

From: Len Brown <[email protected]>

The workaround for AMD erratum 400 uses the term "c1e" suggesting:
1. All AMD processors with AMD C1E are involved
2. Any Intel processors with Intel C1E are involved.

Both are false.

Replace occurrences if "c1e" with "amd_e400" in the code to clarify that it is specific to AMD processors with AMD erratum 400.

This patch is text-substitution only, with no functional change.

cc [email protected]

cc Hans Rosenfeld <[email protected]>

cc Andreas Herrmann <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/acpi.h      |    2 +-
 arch/x86/include/asm/idle.h      |    2 +-
 arch/x86/include/asm/processor.h |    4 ++--
 arch/x86/kernel/cpu/common.c     |    2 +-
 arch/x86/kernel/process.c        |   38 +++++++++++++++++++-------------------
 arch/x86/kernel/smpboot.c        |    2 +-
 drivers/acpi/processor_idle.c    |    2 +-
 7 files changed, 26 insertions(+), 26 deletions(-)

arch/x86/include/asm/acpi.h +1 -1

index 4ea15ca..ae5bc1a 100644
@@ -138,7 +138,7 @@ static inline unsigned int acpi_processor_cstate_check(unsigned int max_cstate)
 	    boot_cpu_data.x86_model <= 0x05 &&
 	    boot_cpu_data.x86_mask < 0x0A)
 		return 1;
-	else if (c1e_detected)
+	else if (amd_e400_detected)
 		return 1;
 	else
 		return max_cstate;

arch/x86/include/asm/idle.h +1 -1

index 38d8737..f49253d7 100644
@@ -16,6 +16,6 @@ static inline void enter_idle(void) { }
 static inline void exit_idle(void) { }
 #endif /* CONFIG_X86_64 */
 
-void c1e_remove_cpu(int cpu);
+void amd_e400_remove_cpu(int cpu);
 
 #endif /* _ASM_X86_IDLE_H */

arch/x86/include/asm/processor.h +2 -2

index 45636ce..a8c5fed 100644
@@ -758,10 +758,10 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
 extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
 
 extern void select_idle_routine(const struct cpuinfo_x86 *c);
-extern void init_c1e_mask(void);
+extern void init_amd_e400_mask(void);
 
 extern unsigned long		boot_option_idle_override;
-extern bool			c1e_detected;
+extern bool			amd_e400_detected;
 
 enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
 			 IDLE_POLL, IDLE_FORCE_MWAIT};

arch/x86/kernel/cpu/common.c +1 -1

index 1d59834..30ce74c 100644
@@ -887,7 +887,7 @@ static void vgetcpu_set_mode(void)
 void __init identify_boot_cpu(void)
 {
 	identify_cpu(&boot_cpu_data);
-	init_c1e_mask();
+	init_amd_e400_mask();
 #ifdef CONFIG_X86_32
 	sysenter_setup();
 	enable_sep_cpu();

arch/x86/kernel/process.c +19 ~~-19~~

index 1f64501..1c45a9c 100644
@@ -540,45 +540,45 @@ int mwait_usable(const struct cpuinfo_x86 *c)
 	return (edx & MWAIT_EDX_C1);
 }
 
-bool c1e_detected;
-EXPORT_SYMBOL(c1e_detected);
+bool amd_e400_detected;
+EXPORT_SYMBOL(amd_e400_detected);
 
-static cpumask_var_t c1e_mask;
+static cpumask_var_t amd_e400_mask;
 
-void c1e_remove_cpu(int cpu)
+void amd_e400_remove_cpu(int cpu)
 {
-	if (c1e_mask != NULL)
-		cpumask_clear_cpu(cpu, c1e_mask);
+	if (amd_e400_mask != NULL)
+		cpumask_clear_cpu(cpu, amd_e400_mask);
 }
 
 /*
- * C1E aware idle routine. We check for C1E active in the interrupt
+ * AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt
  * pending message MSR. If we detect C1E, then we handle it the same
  * way as C3 power states (local apic timer and TSC stop)
  */
-static void c1e_idle(void)
+static void amd_e400_idle(void)
 {
 	if (need_resched())
 		return;
 
-	if (!c1e_detected) {
+	if (!amd_e400_detected) {
 		u32 lo, hi;
 
 		rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
 
 		if (lo & K8_INTP_C1E_ACTIVE_MASK) {
-			c1e_detected = true;
+			amd_e400_detected = true;
 			if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 				mark_tsc_unstable("TSC halt in AMD C1E");
 			printk(KERN_INFO "System has AMD C1E enabled\n");
 		}
 	}
 
-	if (c1e_detected) {
+	if (amd_e400_detected) {
 		int cpu = smp_processor_id();
 
-		if (!cpumask_test_cpu(cpu, c1e_mask)) {
-			cpumask_set_cpu(cpu, c1e_mask);
+		if (!cpumask_test_cpu(cpu, amd_e400_mask)) {
+			cpumask_set_cpu(cpu, amd_e400_mask);
 			/*
 			 * Force broadcast so ACPI can not interfere.
 			 */

@@ -621,17 +621,17 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 		pm_idle = mwait_idle;
 	} else if (cpu_has_amd_erratum(amd_erratum_400)) {
 		/* E400: APIC timer interrupt does not wake up CPU from C1e */
-		printk(KERN_INFO "using C1E aware idle routine\n");
-		pm_idle = c1e_idle;
+		printk(KERN_INFO "using E400 aware idle routine\n");
+		pm_idle = amd_e400_idle;
 	} else
 		pm_idle = default_idle;
 }
 
-void __init init_c1e_mask(void)
+void __init init_amd_e400_mask(void)
 {
-	/* If we're using c1e_idle, we need to allocate c1e_mask. */
-	if (pm_idle == c1e_idle)
-		zalloc_cpumask_var(&c1e_mask, GFP_KERNEL);
+	/* If we're using amd_e400_idle, we need to allocate amd_e400_mask. */
+	if (pm_idle == amd_e400_idle)
+		zalloc_cpumask_var(&amd_e400_mask, GFP_KERNEL);
 }
 
 static int __init idle_setup(char *str)

arch/x86/kernel/smpboot.c +1 -1

index 08776a9..2c33633 100644
@@ -1379,7 +1379,7 @@ void play_dead_common(void)
 {
 	idle_task_exit();
 	reset_lazy_tlbstate();
-	c1e_remove_cpu(raw_smp_processor_id());
+	amd_e400_remove_cpu(raw_smp_processor_id());
 
 	mb();
 	/* Ack it */

drivers/acpi/processor_idle.c +1 -1

index d615b7d..53d9f10 100644
@@ -161,7 +161,7 @@ static void lapic_timer_check_state(int state, struct acpi_processor *pr,
 	if (cpu_has(&cpu_data(pr->id), X86_FEATURE_ARAT))
 		return;
 
-	if (c1e_detected)
+	if (amd_e400_detected)
 		type = ACPI_STATE_C1;
 
 	/*

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:23 UTC #100 lore raw

PATCH 7/18 x86 idle: clarify AMD erratum 400 workaround

In reply to Len Brown

From: Len Brown <[email protected]>

The workaround for AMD erratum 400 uses the term "c1e" suggesting:
1. All AMD processors with AMD C1E are involved
2. Any Intel processors with Intel C1E are involved.

Both are false.

Replace occurrences if "c1e" with "amd_e400" in the code to clarify that it is specific to AMD processors with AMD erratum 400.

This patch is text-substitution only, with no functional change.

cc [email protected]

cc Hans Rosenfeld <[email protected]>

cc Andreas Herrmann <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/acpi.h      |    2 +-
 arch/x86/include/asm/idle.h      |    2 +-
 arch/x86/include/asm/processor.h |    4 ++--
 arch/x86/kernel/cpu/common.c     |    2 +-
 arch/x86/kernel/process.c        |   38 +++++++++++++++++++-------------------
 arch/x86/kernel/smpboot.c        |    2 +-
 drivers/acpi/processor_idle.c    |    2 +-
 7 files changed, 26 insertions(+), 26 deletions(-)

arch/x86/include/asm/acpi.h +1 -1

index 4ea15ca..ae5bc1a 100644
@@ -138,7 +138,7 @@ static inline unsigned int acpi_processor_cstate_check(unsigned int max_cstate)
 	    boot_cpu_data.x86_model <= 0x05 &&
 	    boot_cpu_data.x86_mask < 0x0A)
 		return 1;
-	else if (c1e_detected)
+	else if (amd_e400_detected)
 		return 1;
 	else
 		return max_cstate;

arch/x86/include/asm/idle.h +1 -1

index 38d8737..f49253d7 100644
@@ -16,6 +16,6 @@ static inline void enter_idle(void) { }
 static inline void exit_idle(void) { }
 #endif /* CONFIG_X86_64 */
 
-void c1e_remove_cpu(int cpu);
+void amd_e400_remove_cpu(int cpu);
 
 #endif /* _ASM_X86_IDLE_H */

arch/x86/include/asm/processor.h +2 -2

index 45636ce..a8c5fed 100644
@@ -758,10 +758,10 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
 extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
 
 extern void select_idle_routine(const struct cpuinfo_x86 *c);
-extern void init_c1e_mask(void);
+extern void init_amd_e400_mask(void);
 
 extern unsigned long		boot_option_idle_override;
-extern bool			c1e_detected;
+extern bool			amd_e400_detected;
 
 enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
 			 IDLE_POLL, IDLE_FORCE_MWAIT};

arch/x86/kernel/cpu/common.c +1 -1

index 1d59834..30ce74c 100644
@@ -887,7 +887,7 @@ static void vgetcpu_set_mode(void)
 void __init identify_boot_cpu(void)
 {
 	identify_cpu(&boot_cpu_data);
-	init_c1e_mask();
+	init_amd_e400_mask();
 #ifdef CONFIG_X86_32
 	sysenter_setup();
 	enable_sep_cpu();

arch/x86/kernel/process.c +19 ~~-19~~

index 1f64501..1c45a9c 100644
@@ -540,45 +540,45 @@ int mwait_usable(const struct cpuinfo_x86 *c)
 	return (edx & MWAIT_EDX_C1);
 }
 
-bool c1e_detected;
-EXPORT_SYMBOL(c1e_detected);
+bool amd_e400_detected;
+EXPORT_SYMBOL(amd_e400_detected);
 
-static cpumask_var_t c1e_mask;
+static cpumask_var_t amd_e400_mask;
 
-void c1e_remove_cpu(int cpu)
+void amd_e400_remove_cpu(int cpu)
 {
-	if (c1e_mask != NULL)
-		cpumask_clear_cpu(cpu, c1e_mask);
+	if (amd_e400_mask != NULL)
+		cpumask_clear_cpu(cpu, amd_e400_mask);
 }
 
 /*
- * C1E aware idle routine. We check for C1E active in the interrupt
+ * AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt
  * pending message MSR. If we detect C1E, then we handle it the same
  * way as C3 power states (local apic timer and TSC stop)
  */
-static void c1e_idle(void)
+static void amd_e400_idle(void)
 {
 	if (need_resched())
 		return;
 
-	if (!c1e_detected) {
+	if (!amd_e400_detected) {
 		u32 lo, hi;
 
 		rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
 
 		if (lo & K8_INTP_C1E_ACTIVE_MASK) {
-			c1e_detected = true;
+			amd_e400_detected = true;
 			if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 				mark_tsc_unstable("TSC halt in AMD C1E");
 			printk(KERN_INFO "System has AMD C1E enabled\n");
 		}
 	}
 
-	if (c1e_detected) {
+	if (amd_e400_detected) {
 		int cpu = smp_processor_id();
 
-		if (!cpumask_test_cpu(cpu, c1e_mask)) {
-			cpumask_set_cpu(cpu, c1e_mask);
+		if (!cpumask_test_cpu(cpu, amd_e400_mask)) {
+			cpumask_set_cpu(cpu, amd_e400_mask);
 			/*
 			 * Force broadcast so ACPI can not interfere.
 			 */

@@ -621,17 +621,17 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 		pm_idle = mwait_idle;
 	} else if (cpu_has_amd_erratum(amd_erratum_400)) {
 		/* E400: APIC timer interrupt does not wake up CPU from C1e */
-		printk(KERN_INFO "using C1E aware idle routine\n");
-		pm_idle = c1e_idle;
+		printk(KERN_INFO "using E400 aware idle routine\n");
+		pm_idle = amd_e400_idle;
 	} else
 		pm_idle = default_idle;
 }
 
-void __init init_c1e_mask(void)
+void __init init_amd_e400_mask(void)
 {
-	/* If we're using c1e_idle, we need to allocate c1e_mask. */
-	if (pm_idle == c1e_idle)
-		zalloc_cpumask_var(&c1e_mask, GFP_KERNEL);
+	/* If we're using amd_e400_idle, we need to allocate amd_e400_mask. */
+	if (pm_idle == amd_e400_idle)
+		zalloc_cpumask_var(&amd_e400_mask, GFP_KERNEL);
 }
 
 static int __init idle_setup(char *str)

arch/x86/kernel/smpboot.c +1 -1

index 08776a9..2c33633 100644
@@ -1379,7 +1379,7 @@ void play_dead_common(void)
 {
 	idle_task_exit();
 	reset_lazy_tlbstate();
-	c1e_remove_cpu(raw_smp_processor_id());
+	amd_e400_remove_cpu(raw_smp_processor_id());
 
 	mb();
 	/* Ack it */

drivers/acpi/processor_idle.c +1 -1

index d615b7d..53d9f10 100644
@@ -161,7 +161,7 @@ static void lapic_timer_check_state(int state, struct acpi_processor *pr,
 	if (cpu_has(&cpu_data(pr->id), X86_FEATURE_ARAT))
 		return;
 
-	if (c1e_detected)
+	if (amd_e400_detected)
 		type = ACPI_STATE_C1;
 
 	/*

Signature · 1 line

1.7.5.rc0

Borislav Petkov

maintainer

2011-04-02 08:23 UTC #101 lore raw

Re: [PATCH 07/18] x86 idle: clarify AMD erratum 400 workaround

Quoted 87 lines · Len Brown

From: Len Brown <[email protected]>

The workaround for AMD erratum 400 uses the term "c1e" suggesting:
1. All AMD processors with AMD C1E are involved
2. Any Intel processors with Intel C1E are involved.

Both are false.

Replace occurrences if "c1e" with "amd_e400" in the code to clarify that it is specific to AMD processors with AMD erratum 400.

This patch is text-substitution only, with no functional change.

cc [email protected]

cc Hans Rosenfeld <[email protected]>

cc Andreas Herrmann <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/acpi.h      |    2 +-
 arch/x86/include/asm/idle.h      |    2 +-
 arch/x86/include/asm/processor.h |    4 ++--
 arch/x86/kernel/cpu/common.c     |    2 +-
 arch/x86/kernel/process.c        |   38 +++++++++++++++++++-------------------
 arch/x86/kernel/smpboot.c        |    2 +-
 drivers/acpi/processor_idle.c    |    2 +-
 7 files changed, 26 insertions(+), 26 deletions(-)

arch/x86/include/asm/acpi.h +1 -1

index 4ea15ca..ae5bc1a 100644
@@ -138,7 +138,7 @@ static inline unsigned int acpi_processor_cstate_check(unsigned int max_cstate)
 	    boot_cpu_data.x86_model <= 0x05 &&
 	    boot_cpu_data.x86_mask < 0x0A)
 		return 1;
-	else if (c1e_detected)
+	else if (amd_e400_detected)
 		return 1;
 	else
 		return max_cstate;

arch/x86/include/asm/idle.h +1 -1

index 38d8737..f49253d7 100644
@@ -16,6 +16,6 @@ static inline void enter_idle(void) { }
 static inline void exit_idle(void) { }
 #endif /* CONFIG_X86_64 */
 
-void c1e_remove_cpu(int cpu);
+void amd_e400_remove_cpu(int cpu);
 
 #endif /* _ASM_X86_IDLE_H */

arch/x86/include/asm/processor.h +2 -2

index 45636ce..a8c5fed 100644
@@ -758,10 +758,10 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
 extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
 
 extern void select_idle_routine(const struct cpuinfo_x86 *c);
-extern void init_c1e_mask(void);
+extern void init_amd_e400_mask(void);
 
 extern unsigned long		boot_option_idle_override;
-extern bool			c1e_detected;
+extern bool			amd_e400_detected;
 
 enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
 			 IDLE_POLL, IDLE_FORCE_MWAIT};

arch/x86/kernel/cpu/common.c +1 -1

index 1d59834..30ce74c 100644
@@ -887,7 +887,7 @@ static void vgetcpu_set_mode(void)
 void __init identify_boot_cpu(void)
 {
 	identify_cpu(&boot_cpu_data);
-	init_c1e_mask();
+	init_amd_e400_mask();
 #ifdef CONFIG_X86_32
 	sysenter_setup();
 	enable_sep_cpu();

arch/x86/kernel/process.c +0 -0

index 1f64501..1c45a9c 100644

arch/x86/kernel/process.c int mwait_usable(const struct cpuinfo_x86 *c) · line 546

Quoted 10 lines

arch/x86/kernel/process.c +3 -3

@@ -540,45 +540,45 @@ int mwait_usable(const struct cpuinfo_x86 *c)
 	return (edx & MWAIT_EDX_C1);
 }
 
-bool c1e_detected;
-EXPORT_SYMBOL(c1e_detected);
+bool amd_e400_detected;
+EXPORT_SYMBOL(amd_e400_detected);
 
-static cpumask_var_t c1e_mask;
+static cpumask_var_t amd_e400_mask;

Actually, the correct name should be IMHO

	amd_e400_c1e_mask

Quoted 21 lines

arch/x86/kernel/process.c +5 -5

-void c1e_remove_cpu(int cpu)
+void amd_e400_remove_cpu(int cpu)
 {
-	if (c1e_mask != NULL)
-		cpumask_clear_cpu(cpu, c1e_mask);
+	if (amd_e400_mask != NULL)
+		cpumask_clear_cpu(cpu, amd_e400_mask);
 }
 
 /*
- * C1E aware idle routine. We check for C1E active in the interrupt
+ * AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt
  * pending message MSR. If we detect C1E, then we handle it the same
  * way as C3 power states (local apic timer and TSC stop)
  */
-static void c1e_idle(void)
+static void amd_e400_idle(void)
 {
 	if (need_resched())
 		return;

arch/x86/kernel/process.c int mwait_usable(const struct cpuinfo_x86 *c) · line 570

Quoted 10 lines

arch/x86/kernel/process.c +2 -2

 
-	if (!c1e_detected) {
+	if (!amd_e400_detected) {
 		u32 lo, hi;
 
 		rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
 
 		if (lo & K8_INTP_C1E_ACTIVE_MASK) {
-			c1e_detected = true;
+			amd_e400_detected = true;

Hmm, c1e_detected is still the correct name since those two bits in the INT_PENDING MSR mean simply that the system can either generate an IO read or an SMI to enter C1E irrespective of E400. So I'd leave it c1e_detected.

The function name amd_e400_idle() OTOH looks fine to me since we denote that this is a special idle routine for CPUs affected by E400.

Quoted 21 lines

arch/x86/kernel/process.c +3 -3

 			if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 				mark_tsc_unstable("TSC halt in AMD C1E");
 			printk(KERN_INFO "System has AMD C1E enabled\n");
 		}
 	}
 
-	if (c1e_detected) {
+	if (amd_e400_detected) {
 		int cpu = smp_processor_id();
 
-		if (!cpumask_test_cpu(cpu, c1e_mask)) {
-			cpumask_set_cpu(cpu, c1e_mask);
+		if (!cpumask_test_cpu(cpu, amd_e400_mask)) {
+			cpumask_set_cpu(cpu, amd_e400_mask);
 			/*
 			 * Force broadcast so ACPI can not interfere.
 			 */

@@ -621,17 +621,17 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 		pm_idle = mwait_idle;
 	} else if (cpu_has_amd_erratum(amd_erratum_400)) {
 		/* E400: APIC timer interrupt does not wake up CPU from C1e */

arch/x86/kernel/process.c void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) · line 630

Quoted 10 lines

arch/x86/kernel/process.c +3 -3

-		printk(KERN_INFO "using C1E aware idle routine\n");
-		pm_idle = c1e_idle;
+		printk(KERN_INFO "using E400 aware idle routine\n");
+		pm_idle = amd_e400_idle;
 	} else
 		pm_idle = default_idle;
 }
 
-void __init init_c1e_mask(void)
+void __init init_amd_e400_mask(void)

Same here, init_amd_e400_c1e_mask.

Quoted 38 lines

arch/x86/kernel/process.c +3 -3

 {
-	/* If we're using c1e_idle, we need to allocate c1e_mask. */
-	if (pm_idle == c1e_idle)
-		zalloc_cpumask_var(&c1e_mask, GFP_KERNEL);
+	/* If we're using amd_e400_idle, we need to allocate amd_e400_mask. */
+	if (pm_idle == amd_e400_idle)
+		zalloc_cpumask_var(&amd_e400_mask, GFP_KERNEL);
 }
 
 static int __init idle_setup(char *str)

arch/x86/kernel/smpboot.c +1 -1

index 08776a9..2c33633 100644
@@ -1379,7 +1379,7 @@ void play_dead_common(void)
 {
 	idle_task_exit();
 	reset_lazy_tlbstate();
-	c1e_remove_cpu(raw_smp_processor_id());
+	amd_e400_remove_cpu(raw_smp_processor_id());
 
 	mb();
 	/* Ack it */

drivers/acpi/processor_idle.c +1 -1

index d615b7d..53d9f10 100644
@@ -161,7 +161,7 @@ static void lapic_timer_check_state(int state, struct acpi_processor *pr,
 	if (cpu_has(&cpu_data(pr->id), X86_FEATURE_ARAT))
 		return;
 
-	if (c1e_detected)
+	if (amd_e400_detected)
 		type = ACPI_STATE_C1;
 
 	/*

Signature · 1 line

1.7.5.rc0

Thanks.

Signature · 2 lines

Regards/Gruss,
    Boris.

Borislav Petkov

maintainer

2011-04-02 08:23 UTC #102 lore raw

Re: [PATCH 07/18] x86 idle: clarify AMD erratum 400 workaround

In reply to Len Brown

Quoted 87 lines · Len Brown

From: Len Brown <[email protected]>

The workaround for AMD erratum 400 uses the term "c1e" suggesting:
1. All AMD processors with AMD C1E are involved
2. Any Intel processors with Intel C1E are involved.

Both are false.

Replace occurrences if "c1e" with "amd_e400" in the code to clarify that it is specific to AMD processors with AMD erratum 400.

This patch is text-substitution only, with no functional change.

cc [email protected]

cc Hans Rosenfeld <[email protected]>

cc Andreas Herrmann <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/acpi.h      |    2 +-
 arch/x86/include/asm/idle.h      |    2 +-
 arch/x86/include/asm/processor.h |    4 ++--
 arch/x86/kernel/cpu/common.c     |    2 +-
 arch/x86/kernel/process.c        |   38 +++++++++++++++++++-------------------
 arch/x86/kernel/smpboot.c        |    2 +-
 drivers/acpi/processor_idle.c    |    2 +-
 7 files changed, 26 insertions(+), 26 deletions(-)

arch/x86/include/asm/acpi.h +1 -1

index 4ea15ca..ae5bc1a 100644
@@ -138,7 +138,7 @@ static inline unsigned int acpi_processor_cstate_check(unsigned int max_cstate)
 	    boot_cpu_data.x86_model <= 0x05 &&
 	    boot_cpu_data.x86_mask < 0x0A)
 		return 1;
-	else if (c1e_detected)
+	else if (amd_e400_detected)
 		return 1;
 	else
 		return max_cstate;

arch/x86/include/asm/idle.h +1 -1

index 38d8737..f49253d7 100644
@@ -16,6 +16,6 @@ static inline void enter_idle(void) { }
 static inline void exit_idle(void) { }
 #endif /* CONFIG_X86_64 */
 
-void c1e_remove_cpu(int cpu);
+void amd_e400_remove_cpu(int cpu);
 
 #endif /* _ASM_X86_IDLE_H */

arch/x86/include/asm/processor.h +2 -2

index 45636ce..a8c5fed 100644
@@ -758,10 +758,10 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
 extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
 
 extern void select_idle_routine(const struct cpuinfo_x86 *c);
-extern void init_c1e_mask(void);
+extern void init_amd_e400_mask(void);
 
 extern unsigned long		boot_option_idle_override;
-extern bool			c1e_detected;
+extern bool			amd_e400_detected;
 
 enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
 			 IDLE_POLL, IDLE_FORCE_MWAIT};

arch/x86/kernel/cpu/common.c +1 -1

index 1d59834..30ce74c 100644
@@ -887,7 +887,7 @@ static void vgetcpu_set_mode(void)
 void __init identify_boot_cpu(void)
 {
 	identify_cpu(&boot_cpu_data);
-	init_c1e_mask();
+	init_amd_e400_mask();
 #ifdef CONFIG_X86_32
 	sysenter_setup();
 	enable_sep_cpu();

arch/x86/kernel/process.c +0 -0

index 1f64501..1c45a9c 100644

arch/x86/kernel/process.c int mwait_usable(const struct cpuinfo_x86 *c) · line 546

Quoted 10 lines

arch/x86/kernel/process.c +3 -3

@@ -540,45 +540,45 @@ int mwait_usable(const struct cpuinfo_x86 *c)
 	return (edx & MWAIT_EDX_C1);
 }
 
-bool c1e_detected;
-EXPORT_SYMBOL(c1e_detected);
+bool amd_e400_detected;
+EXPORT_SYMBOL(amd_e400_detected);
 
-static cpumask_var_t c1e_mask;
+static cpumask_var_t amd_e400_mask;

Actually, the correct name should be IMHO

	amd_e400_c1e_mask

Quoted 21 lines

arch/x86/kernel/process.c +5 -5

-void c1e_remove_cpu(int cpu)
+void amd_e400_remove_cpu(int cpu)
 {
-	if (c1e_mask != NULL)
-		cpumask_clear_cpu(cpu, c1e_mask);
+	if (amd_e400_mask != NULL)
+		cpumask_clear_cpu(cpu, amd_e400_mask);
 }
 
 /*
- * C1E aware idle routine. We check for C1E active in the interrupt
+ * AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt
  * pending message MSR. If we detect C1E, then we handle it the same
  * way as C3 power states (local apic timer and TSC stop)
  */
-static void c1e_idle(void)
+static void amd_e400_idle(void)
 {
 	if (need_resched())
 		return;

arch/x86/kernel/process.c int mwait_usable(const struct cpuinfo_x86 *c) · line 570

Quoted 10 lines

arch/x86/kernel/process.c +2 -2

 
-	if (!c1e_detected) {
+	if (!amd_e400_detected) {
 		u32 lo, hi;
 
 		rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
 
 		if (lo & K8_INTP_C1E_ACTIVE_MASK) {
-			c1e_detected = true;
+			amd_e400_detected = true;

The function name amd_e400_idle() OTOH looks fine to me since we denote that this is a special idle routine for CPUs affected by E400.

Quoted 21 lines

arch/x86/kernel/process.c +3 -3

 			if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 				mark_tsc_unstable("TSC halt in AMD C1E");
 			printk(KERN_INFO "System has AMD C1E enabled\n");
 		}
 	}
 
-	if (c1e_detected) {
+	if (amd_e400_detected) {
 		int cpu = smp_processor_id();
 
-		if (!cpumask_test_cpu(cpu, c1e_mask)) {
-			cpumask_set_cpu(cpu, c1e_mask);
+		if (!cpumask_test_cpu(cpu, amd_e400_mask)) {
+			cpumask_set_cpu(cpu, amd_e400_mask);
 			/*
 			 * Force broadcast so ACPI can not interfere.
 			 */

@@ -621,17 +621,17 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 		pm_idle = mwait_idle;
 	} else if (cpu_has_amd_erratum(amd_erratum_400)) {
 		/* E400: APIC timer interrupt does not wake up CPU from C1e */

arch/x86/kernel/process.c void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) · line 630

Quoted 10 lines

arch/x86/kernel/process.c +3 -3

-		printk(KERN_INFO "using C1E aware idle routine\n");
-		pm_idle = c1e_idle;
+		printk(KERN_INFO "using E400 aware idle routine\n");
+		pm_idle = amd_e400_idle;
 	} else
 		pm_idle = default_idle;
 }
 
-void __init init_c1e_mask(void)
+void __init init_amd_e400_mask(void)

Same here, init_amd_e400_c1e_mask.

Quoted 38 lines

arch/x86/kernel/process.c +3 -3

 {
-	/* If we're using c1e_idle, we need to allocate c1e_mask. */
-	if (pm_idle == c1e_idle)
-		zalloc_cpumask_var(&c1e_mask, GFP_KERNEL);
+	/* If we're using amd_e400_idle, we need to allocate amd_e400_mask. */
+	if (pm_idle == amd_e400_idle)
+		zalloc_cpumask_var(&amd_e400_mask, GFP_KERNEL);
 }
 
 static int __init idle_setup(char *str)

arch/x86/kernel/smpboot.c +1 -1

index 08776a9..2c33633 100644
@@ -1379,7 +1379,7 @@ void play_dead_common(void)
 {
 	idle_task_exit();
 	reset_lazy_tlbstate();
-	c1e_remove_cpu(raw_smp_processor_id());
+	amd_e400_remove_cpu(raw_smp_processor_id());
 
 	mb();
 	/* Ack it */

drivers/acpi/processor_idle.c +1 -1

index d615b7d..53d9f10 100644
@@ -161,7 +161,7 @@ static void lapic_timer_check_state(int state, struct acpi_processor *pr,
 	if (cpu_has(&cpu_data(pr->id), X86_FEATURE_ARAT))
 		return;
 
-	if (c1e_detected)
+	if (amd_e400_detected)
 		type = ACPI_STATE_C1;
 
 	/*

Signature · 1 line

1.7.5.rc0

Thanks.

Signature · 2 lines

Regards/Gruss,
    Boris.

Len Brown

author reviewer

2011-04-02 19:19 UTC #103 lore raw

Re: [PATCH 07/18] x86 idle: clarify AMD erratum 400 workaround

Quoted 6 lines

arch/x86/kernel/process.c int mwait_usable(const struct cpuinfo_x86 *c) · line 546
Quoted 2 lines
arch/x86/kernel/process.c +1 -1
-static cpumask_var_t c1e_mask;
+static cpumask_var_t amd_e400_mask;
Actually, the correct name should be IMHO
	amd_e400_c1e_mask

okay.

Quoted 7 lines

arch/x86/kernel/process.c int mwait_usable(const struct cpuinfo_x86 *c) · line 570
Quoted 2 lines
arch/x86/kernel/process.c +1 -1
-			c1e_detected = true;
+			amd_e400_detected = true;
Hmm, c1e_detected is still the correct name since those two bits in the INT_PENDING MSR mean simply that the system can either generate an IO read or an SMI to enter C1E irrespective of E400. So I'd leave it c1e_detected.

We don't run the code that sets this flag unless
cpu_has_amd_erratum(amd_erratum_400)

so how about this?:

- c1e_detected
+ amd_e400_c1e_detected

Quoted 4 lines

arch/x86/kernel/process.c void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) · line 630
Quoted 2 lines
arch/x86/kernel/process.c +1 -1
-void __init init_c1e_mask(void)
+void __init init_amd_e400_mask(void)
Same here, init_amd_e400_c1e_mask.

done.

thanks,
Len Brown, Intel Open Source Technology Center

Len Brown

author reviewer

2011-04-02 19:20 UTC #104 lore raw

Re: [PATCH 07/18] x86 idle: clarify AMD erratum 400 workaround

In reply to Borislav Petkov

Quoted 6 lines

arch/x86/kernel/process.c int mwait_usable(const struct cpuinfo_x86 *c) · line 546
Quoted 2 lines
arch/x86/kernel/process.c +1 -1
-static cpumask_var_t c1e_mask;
+static cpumask_var_t amd_e400_mask;
Actually, the correct name should be IMHO
	amd_e400_c1e_mask

okay.

Quoted 7 lines

arch/x86/kernel/process.c int mwait_usable(const struct cpuinfo_x86 *c) · line 570
Quoted 2 lines
arch/x86/kernel/process.c +1 -1
-			c1e_detected = true;
+			amd_e400_detected = true;
Hmm, c1e_detected is still the correct name since those two bits in the INT_PENDING MSR mean simply that the system can either generate an IO read or an SMI to enter C1E irrespective of E400. So I'd leave it c1e_detected.

We don't run the code that sets this flag unless
cpu_has_amd_erratum(amd_erratum_400)

so how about this?:

- c1e_detected
+ amd_e400_c1e_detected

Quoted 4 lines

arch/x86/kernel/process.c void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) · line 630
Quoted 2 lines
arch/x86/kernel/process.c +1 -1
-void __init init_c1e_mask(void)
+void __init init_amd_e400_mask(void)
Same here, init_amd_e400_c1e_mask.

done.

thanks,
Len Brown, Intel Open Source Technology Center

Len Brown

author reviewer

2011-04-02 19:22 UTC #105 lore raw

PATCH 7/18 x86 idle: clarify AMD erratum 400 workaround -v2

From: Len Brown <[email protected]>

The workaround for AMD erratum 400 uses the term "c1e" falsely suggesting:
1. Intel C1E is somehow involved
2. All AMD processors with C1E are involved

Use the string "amd_c1e" instead of simply "c1e" to clarify that this workaround is specific to AMD's version of C1E. Use the string "e400" to clarify that the workaround is specific to AMD processors with Erratum 400.

This patch is text-substitution only, with no functional change.

cc [email protected]

cc Hans Rosenfeld <[email protected]>

cc Andreas Herrmann <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/acpi.h      |    2 +-
 arch/x86/include/asm/idle.h      |    2 +-
 arch/x86/include/asm/processor.h |    4 ++--
 arch/x86/kernel/cpu/common.c     |    2 +-
 arch/x86/kernel/process.c        |   38 +++++++++++++++++++-------------------
 arch/x86/kernel/smpboot.c        |    2 +-
 drivers/acpi/processor_idle.c    |    2 +-
 7 files changed, 26 insertions(+), 26 deletions(-)

arch/x86/include/asm/acpi.h +1 -1

index 4ea15ca..52fd57f 100644
@@ -138,7 +138,7 @@ static inline unsigned int acpi_processor_cstate_check(unsigned int max_cstate)
 	    boot_cpu_data.x86_model <= 0x05 &&
 	    boot_cpu_data.x86_mask < 0x0A)
 		return 1;
-	else if (c1e_detected)
+	else if (amd_e400_c1e_detected)
 		return 1;
 	else
 		return max_cstate;

arch/x86/include/asm/idle.h +1 -1

index 38d8737..f49253d7 100644
@@ -16,6 +16,6 @@ static inline void enter_idle(void) { }
 static inline void exit_idle(void) { }
 #endif /* CONFIG_X86_64 */
 
-void c1e_remove_cpu(int cpu);
+void amd_e400_remove_cpu(int cpu);
 
 #endif /* _ASM_X86_IDLE_H */

arch/x86/include/asm/processor.h +2 -2

index 45636ce..03d38f7 100644
@@ -758,10 +758,10 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
 extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
 
 extern void select_idle_routine(const struct cpuinfo_x86 *c);
-extern void init_c1e_mask(void);
+extern void init_amd_e400_mask(void);
 
 extern unsigned long		boot_option_idle_override;
-extern bool			c1e_detected;
+extern bool			amd_e400_c1e_detected;
 
 enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
 			 IDLE_POLL, IDLE_FORCE_MWAIT};

arch/x86/kernel/cpu/common.c +1 -1

index 1d59834..30ce74c 100644
@@ -887,7 +887,7 @@ static void vgetcpu_set_mode(void)
 void __init identify_boot_cpu(void)
 {
 	identify_cpu(&boot_cpu_data);
-	init_c1e_mask();
+	init_amd_e400_mask();
 #ifdef CONFIG_X86_32
 	sysenter_setup();
 	enable_sep_cpu();

arch/x86/kernel/process.c +19 ~~-19~~

index 1f64501..38b3f5d 100644
@@ -540,45 +540,45 @@ int mwait_usable(const struct cpuinfo_x86 *c)
 	return (edx & MWAIT_EDX_C1);
 }
 
-bool c1e_detected;
-EXPORT_SYMBOL(c1e_detected);
+bool amd_e400_c1e_detected;
+EXPORT_SYMBOL(amd_e400_c1e_detected);
 
-static cpumask_var_t c1e_mask;
+static cpumask_var_t amd_e400_c1e_mask;
 
-void c1e_remove_cpu(int cpu)
+void amd_e400_remove_cpu(int cpu)
 {
-	if (c1e_mask != NULL)
-		cpumask_clear_cpu(cpu, c1e_mask);
+	if (amd_e400_c1e_mask != NULL)
+		cpumask_clear_cpu(cpu, amd_e400_c1e_mask);
 }
 
 /*
- * C1E aware idle routine. We check for C1E active in the interrupt
+ * AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt
  * pending message MSR. If we detect C1E, then we handle it the same
  * way as C3 power states (local apic timer and TSC stop)
  */
-static void c1e_idle(void)
+static void amd_e400_idle(void)
 {
 	if (need_resched())
 		return;
 
-	if (!c1e_detected) {
+	if (!amd_e400_c1e_detected) {
 		u32 lo, hi;
 
 		rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
 
 		if (lo & K8_INTP_C1E_ACTIVE_MASK) {
-			c1e_detected = true;
+			amd_e400_c1e_detected = true;
 			if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 				mark_tsc_unstable("TSC halt in AMD C1E");
 			printk(KERN_INFO "System has AMD C1E enabled\n");
 		}
 	}
 
-	if (c1e_detected) {
+	if (amd_e400_c1e_detected) {
 		int cpu = smp_processor_id();
 
-		if (!cpumask_test_cpu(cpu, c1e_mask)) {
-			cpumask_set_cpu(cpu, c1e_mask);
+		if (!cpumask_test_cpu(cpu, amd_e400_c1e_mask)) {
+			cpumask_set_cpu(cpu, amd_e400_c1e_mask);
 			/*
 			 * Force broadcast so ACPI can not interfere.
 			 */

@@ -621,17 +621,17 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 		pm_idle = mwait_idle;
 	} else if (cpu_has_amd_erratum(amd_erratum_400)) {
 		/* E400: APIC timer interrupt does not wake up CPU from C1e */
-		printk(KERN_INFO "using C1E aware idle routine\n");
-		pm_idle = c1e_idle;
+		printk(KERN_INFO "using AMD E400 aware idle routine\n");
+		pm_idle = amd_e400_idle;
 	} else
 		pm_idle = default_idle;
 }
 
-void __init init_c1e_mask(void)
+void __init init_amd_e400_c1e_mask(void)
 {
-	/* If we're using c1e_idle, we need to allocate c1e_mask. */
-	if (pm_idle == c1e_idle)
-		zalloc_cpumask_var(&c1e_mask, GFP_KERNEL);
+	/* If we're using amd_e400_idle, we need to allocate amd_e400_c1e_mask. */
+	if (pm_idle == amd_e400_idle)
+		zalloc_cpumask_var(&amd_e400_c1e_mask, GFP_KERNEL);
 }
 
 static int __init idle_setup(char *str)

arch/x86/kernel/smpboot.c +1 -1

index 08776a9..2c33633 100644
@@ -1379,7 +1379,7 @@ void play_dead_common(void)
 {
 	idle_task_exit();
 	reset_lazy_tlbstate();
-	c1e_remove_cpu(raw_smp_processor_id());
+	amd_e400_remove_cpu(raw_smp_processor_id());
 
 	mb();
 	/* Ack it */

drivers/acpi/processor_idle.c +1 -1

index d615b7d..431ab11 100644
@@ -161,7 +161,7 @@ static void lapic_timer_check_state(int state, struct acpi_processor *pr,
 	if (cpu_has(&cpu_data(pr->id), X86_FEATURE_ARAT))
 		return;
 
-	if (c1e_detected)
+	if (amd_e400_c1e_detected)
 		type = ACPI_STATE_C1;
 
 	/*

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 19:22 UTC #106 lore raw

PATCH 7/18 x86 idle: clarify AMD erratum 400 workaround -v2

In reply to Len Brown

From: Len Brown <[email protected]>

The workaround for AMD erratum 400 uses the term "c1e" falsely suggesting:
1. Intel C1E is somehow involved
2. All AMD processors with C1E are involved

This patch is text-substitution only, with no functional change.

cc [email protected]

cc Hans Rosenfeld <[email protected]>

cc Andreas Herrmann <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/acpi.h      |    2 +-
 arch/x86/include/asm/idle.h      |    2 +-
 arch/x86/include/asm/processor.h |    4 ++--
 arch/x86/kernel/cpu/common.c     |    2 +-
 arch/x86/kernel/process.c        |   38 +++++++++++++++++++-------------------
 arch/x86/kernel/smpboot.c        |    2 +-
 drivers/acpi/processor_idle.c    |    2 +-
 7 files changed, 26 insertions(+), 26 deletions(-)

arch/x86/include/asm/acpi.h +1 -1

index 4ea15ca..52fd57f 100644
@@ -138,7 +138,7 @@ static inline unsigned int acpi_processor_cstate_check(unsigned int max_cstate)
 	    boot_cpu_data.x86_model <= 0x05 &&
 	    boot_cpu_data.x86_mask < 0x0A)
 		return 1;
-	else if (c1e_detected)
+	else if (amd_e400_c1e_detected)
 		return 1;
 	else
 		return max_cstate;

arch/x86/include/asm/idle.h +1 -1

index 38d8737..f49253d7 100644
@@ -16,6 +16,6 @@ static inline void enter_idle(void) { }
 static inline void exit_idle(void) { }
 #endif /* CONFIG_X86_64 */
 
-void c1e_remove_cpu(int cpu);
+void amd_e400_remove_cpu(int cpu);
 
 #endif /* _ASM_X86_IDLE_H */

arch/x86/include/asm/processor.h +2 -2

index 45636ce..03d38f7 100644
@@ -758,10 +758,10 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
 extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
 
 extern void select_idle_routine(const struct cpuinfo_x86 *c);
-extern void init_c1e_mask(void);
+extern void init_amd_e400_mask(void);
 
 extern unsigned long		boot_option_idle_override;
-extern bool			c1e_detected;
+extern bool			amd_e400_c1e_detected;
 
 enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
 			 IDLE_POLL, IDLE_FORCE_MWAIT};

arch/x86/kernel/cpu/common.c +1 -1

index 1d59834..30ce74c 100644
@@ -887,7 +887,7 @@ static void vgetcpu_set_mode(void)
 void __init identify_boot_cpu(void)
 {
 	identify_cpu(&boot_cpu_data);
-	init_c1e_mask();
+	init_amd_e400_mask();
 #ifdef CONFIG_X86_32
 	sysenter_setup();
 	enable_sep_cpu();

arch/x86/kernel/process.c +19 ~~-19~~

index 1f64501..38b3f5d 100644
@@ -540,45 +540,45 @@ int mwait_usable(const struct cpuinfo_x86 *c)
 	return (edx & MWAIT_EDX_C1);
 }
 
-bool c1e_detected;
-EXPORT_SYMBOL(c1e_detected);
+bool amd_e400_c1e_detected;
+EXPORT_SYMBOL(amd_e400_c1e_detected);
 
-static cpumask_var_t c1e_mask;
+static cpumask_var_t amd_e400_c1e_mask;
 
-void c1e_remove_cpu(int cpu)
+void amd_e400_remove_cpu(int cpu)
 {
-	if (c1e_mask != NULL)
-		cpumask_clear_cpu(cpu, c1e_mask);
+	if (amd_e400_c1e_mask != NULL)
+		cpumask_clear_cpu(cpu, amd_e400_c1e_mask);
 }
 
 /*
- * C1E aware idle routine. We check for C1E active in the interrupt
+ * AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt
  * pending message MSR. If we detect C1E, then we handle it the same
  * way as C3 power states (local apic timer and TSC stop)
  */
-static void c1e_idle(void)
+static void amd_e400_idle(void)
 {
 	if (need_resched())
 		return;
 
-	if (!c1e_detected) {
+	if (!amd_e400_c1e_detected) {
 		u32 lo, hi;
 
 		rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
 
 		if (lo & K8_INTP_C1E_ACTIVE_MASK) {
-			c1e_detected = true;
+			amd_e400_c1e_detected = true;
 			if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 				mark_tsc_unstable("TSC halt in AMD C1E");
 			printk(KERN_INFO "System has AMD C1E enabled\n");
 		}
 	}
 
-	if (c1e_detected) {
+	if (amd_e400_c1e_detected) {
 		int cpu = smp_processor_id();
 
-		if (!cpumask_test_cpu(cpu, c1e_mask)) {
-			cpumask_set_cpu(cpu, c1e_mask);
+		if (!cpumask_test_cpu(cpu, amd_e400_c1e_mask)) {
+			cpumask_set_cpu(cpu, amd_e400_c1e_mask);
 			/*
 			 * Force broadcast so ACPI can not interfere.
 			 */

@@ -621,17 +621,17 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 		pm_idle = mwait_idle;
 	} else if (cpu_has_amd_erratum(amd_erratum_400)) {
 		/* E400: APIC timer interrupt does not wake up CPU from C1e */
-		printk(KERN_INFO "using C1E aware idle routine\n");
-		pm_idle = c1e_idle;
+		printk(KERN_INFO "using AMD E400 aware idle routine\n");
+		pm_idle = amd_e400_idle;
 	} else
 		pm_idle = default_idle;
 }
 
-void __init init_c1e_mask(void)
+void __init init_amd_e400_c1e_mask(void)
 {
-	/* If we're using c1e_idle, we need to allocate c1e_mask. */
-	if (pm_idle == c1e_idle)
-		zalloc_cpumask_var(&c1e_mask, GFP_KERNEL);
+	/* If we're using amd_e400_idle, we need to allocate amd_e400_c1e_mask. */
+	if (pm_idle == amd_e400_idle)
+		zalloc_cpumask_var(&amd_e400_c1e_mask, GFP_KERNEL);
 }
 
 static int __init idle_setup(char *str)

arch/x86/kernel/smpboot.c +1 -1

index 08776a9..2c33633 100644
@@ -1379,7 +1379,7 @@ void play_dead_common(void)
 {
 	idle_task_exit();
 	reset_lazy_tlbstate();
-	c1e_remove_cpu(raw_smp_processor_id());
+	amd_e400_remove_cpu(raw_smp_processor_id());
 
 	mb();
 	/* Ack it */

drivers/acpi/processor_idle.c +1 -1

index d615b7d..431ab11 100644
@@ -161,7 +161,7 @@ static void lapic_timer_check_state(int state, struct acpi_processor *pr,
 	if (cpu_has(&cpu_data(pr->id), X86_FEATURE_ARAT))
 		return;
 
-	if (c1e_detected)
+	if (amd_e400_c1e_detected)
 		type = ACPI_STATE_C1;
 
 	/*

Signature · 1 line

1.7.5.rc0

Borislav Petkov

Acked-by on v1 7/18

2011-04-03 09:00 UTC #107 lore raw

Re: [PATCH 07/18] x86 idle: clarify AMD erratum 400 workaround -v2

Quoted 11 lines · Len Brown

From: Len Brown <[email protected]>
The workaround for AMD erratum 400 uses the term "c1e" falsely suggesting:
1. Intel C1E is somehow involved
2. All AMD processors with C1E are involved
Use the string "amd_c1e" instead of simply "c1e" to clarify that this workaround is specific to AMD's version of C1E. Use the string "e400" to clarify that the workaround is specific to AMD processors with Erratum 400.

Quoted 6 lines

This patch is text-substitution only, with no functional change.
cc [email protected]
cc Hans Rosenfeld <[email protected]>
cc Andreas Herrmann <[email protected]>
Signed-off-by Len Brown <[email protected]>

Looks good, thanks.

Acked-by Borislav Petkov <[email protected]>

Signature · 8 lines

Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
General Managers: Alberto Bozzo, Andrew Bowd
Registration: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632

Borislav Petkov

Acked-by on v1 7/18

2011-04-03 09:00 UTC #108 lore raw

Re: [PATCH 07/18] x86 idle: clarify AMD erratum 400 workaround -v2

In reply to Len Brown

Quoted 11 lines · Len Brown

From: Len Brown <[email protected]>
The workaround for AMD erratum 400 uses the term "c1e" falsely suggesting:
1. Intel C1E is somehow involved
2. All AMD processors with C1E are involved
Use the string "amd_c1e" instead of simply "c1e" to clarify that this workaround is specific to AMD's version of C1E. Use the string "e400" to clarify that the workaround is specific to AMD processors with Erratum 400.

Quoted 6 lines

This patch is text-substitution only, with no functional change.
cc [email protected]
cc Hans Rosenfeld <[email protected]>
cc Andreas Herrmann <[email protected]>
Signed-off-by Len Brown <[email protected]>

Looks good, thanks.

Acked-by Borislav Petkov <[email protected]>

Signature · 8 lines

Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
General Managers: Alberto Bozzo, Andrew Bowd
Registration: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632

Len Brown

author reviewer

2011-04-02 06:22 UTC #109 lore raw

PATCH 8/18 cpuidle: create bootparam "cpuidle.off=1"

In reply to Len Brown

From: Len Brown <[email protected]>

useful for disabling cpuidle to fall back
to architecture-default idle loop

cpuidle drivers and governors will fail to register. on x86 they'll say so:

intel_idle: intel_idle yielding to (null)
ACPI: acpi_idle yielding to (null)

Signed-off-by Len Brown <[email protected]>

---
 Documentation/kernel-parameters.txt |    3 +++
 drivers/cpuidle/cpuidle.c           |   10 ++++++++++
 drivers/cpuidle/cpuidle.h           |    1 +
 drivers/cpuidle/driver.c            |    3 +++
 drivers/cpuidle/governor.c          |    3 +++
 5 files changed, 20 insertions(+), 0 deletions(-)

Documentation/kernel-parameters.txt +3 -0

index f4a04c0..08e8a22 100644
@@ -546,6 +546,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			/proc/<pid>/coredump_filter.
 			See also Documentation/filesystems/proc.txt.
 
+	cpuidle.off=1	[CPU_IDLE]
+			disable the cpuidle sub-system
+
 	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
 			Format:
 			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]

drivers/cpuidle/cpuidle.c +10 -0

index bf50924..faae2c3 100644
@@ -28,6 +28,12 @@ LIST_HEAD(cpuidle_detected_devices);
 static void (*pm_idle_old)(void);
 
 static int enabled_devices;
+static int off __read_mostly;
+
+int cpuidle_disabled(void)
+{
+	return off;
+}
 
 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
 static void cpuidle_kick_cpus(void)

@@ -427,6 +433,9 @@ static int __init cpuidle_init(void)
 {
 	int ret;
 
+	if (cpuidle_disabled())
+		return -ENODEV;
+
 	pm_idle_old = pm_idle;
 
 	ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);

@@ -438,4 +447,5 @@ static int __init cpuidle_init(void)
 	return 0;
 }
 
+module_param(off, int, 0444);
 core_initcall(cpuidle_init);

drivers/cpuidle/cpuidle.h +1 -0

index 33e50d5..38c3fd8 100644
@@ -13,6 +13,7 @@ extern struct list_head cpuidle_governors;
 extern struct list_head cpuidle_detected_devices;
 extern struct mutex cpuidle_lock;
 extern spinlock_t cpuidle_driver_lock;
+extern int cpuidle_disabled(void);
 
 /* idle loop */
 extern void cpuidle_install_idle_handler(void);

drivers/cpuidle/driver.c +3 -0

index fd1601e..3f7e3ce 100644
@@ -26,6 +26,9 @@ int cpuidle_register_driver(struct cpuidle_driver *drv)
 	if (!drv)
 		return -EINVAL;
 
+	if (cpuidle_disabled())
+		return -ENODEV;
+
 	spin_lock(&cpuidle_driver_lock);
 	if (cpuidle_curr_driver) {
 		spin_unlock(&cpuidle_driver_lock);

drivers/cpuidle/governor.c +3 -0

index 724c164..ea2f8e7 100644
@@ -81,6 +81,9 @@ int cpuidle_register_governor(struct cpuidle_governor *gov)
 	if (!gov || !gov->select)
 		return -EINVAL;
 
+	if (cpuidle_disabled())
+		return -ENODEV;
+
 	mutex_lock(&cpuidle_lock);
 	if (__cpuidle_find_governor(gov->name) == NULL) {
 		ret = 0;

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:23 UTC #110 lore raw

PATCH 8/18 cpuidle: create bootparam "cpuidle.off=1"

In reply to Len Brown

From: Len Brown <[email protected]>

useful for disabling cpuidle to fall back
to architecture-default idle loop

cpuidle drivers and governors will fail to register. on x86 they'll say so:

intel_idle: intel_idle yielding to (null)
ACPI: acpi_idle yielding to (null)

Signed-off-by Len Brown <[email protected]>

---
 Documentation/kernel-parameters.txt |    3 +++
 drivers/cpuidle/cpuidle.c           |   10 ++++++++++
 drivers/cpuidle/cpuidle.h           |    1 +
 drivers/cpuidle/driver.c            |    3 +++
 drivers/cpuidle/governor.c          |    3 +++
 5 files changed, 20 insertions(+), 0 deletions(-)

Documentation/kernel-parameters.txt +3 -0

index f4a04c0..08e8a22 100644
@@ -546,6 +546,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			/proc/<pid>/coredump_filter.
 			See also Documentation/filesystems/proc.txt.
 
+	cpuidle.off=1	[CPU_IDLE]
+			disable the cpuidle sub-system
+
 	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
 			Format:
 			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]

drivers/cpuidle/cpuidle.c +10 -0

index bf50924..faae2c3 100644
@@ -28,6 +28,12 @@ LIST_HEAD(cpuidle_detected_devices);
 static void (*pm_idle_old)(void);
 
 static int enabled_devices;
+static int off __read_mostly;
+
+int cpuidle_disabled(void)
+{
+	return off;
+}
 
 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
 static void cpuidle_kick_cpus(void)

@@ -427,6 +433,9 @@ static int __init cpuidle_init(void)
 {
 	int ret;
 
+	if (cpuidle_disabled())
+		return -ENODEV;
+
 	pm_idle_old = pm_idle;
 
 	ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);

@@ -438,4 +447,5 @@ static int __init cpuidle_init(void)
 	return 0;
 }
 
+module_param(off, int, 0444);
 core_initcall(cpuidle_init);

drivers/cpuidle/cpuidle.h +1 -0

index 33e50d5..38c3fd8 100644
@@ -13,6 +13,7 @@ extern struct list_head cpuidle_governors;
 extern struct list_head cpuidle_detected_devices;
 extern struct mutex cpuidle_lock;
 extern spinlock_t cpuidle_driver_lock;
+extern int cpuidle_disabled(void);
 
 /* idle loop */
 extern void cpuidle_install_idle_handler(void);

drivers/cpuidle/driver.c +3 -0

index fd1601e..3f7e3ce 100644
@@ -26,6 +26,9 @@ int cpuidle_register_driver(struct cpuidle_driver *drv)
 	if (!drv)
 		return -EINVAL;
 
+	if (cpuidle_disabled())
+		return -ENODEV;
+
 	spin_lock(&cpuidle_driver_lock);
 	if (cpuidle_curr_driver) {
 		spin_unlock(&cpuidle_driver_lock);

drivers/cpuidle/governor.c +3 -0

index 724c164..ea2f8e7 100644
@@ -81,6 +81,9 @@ int cpuidle_register_governor(struct cpuidle_governor *gov)
 	if (!gov || !gov->select)
 		return -EINVAL;
 
+	if (cpuidle_disabled())
+		return -ENODEV;
+
 	mutex_lock(&cpuidle_lock);
 	if (__cpuidle_find_governor(gov->name) == NULL) {
 		ret = 0;

Signature · 1 line

1.7.5.rc0

Deepthi Dharwar

2011-07-15 11:27 UTC #111 lore raw

Re: [PATCH 08/18] cpuidle: create bootparam "cpuidle.off=1"

Quoted 98 lines · Len Brown

From: Len Brown <[email protected]>

useful for disabling cpuidle to fall back
to architecture-default idle loop

cpuidle drivers and governors will fail to register. on x86 they'll say so:

intel_idle: intel_idle yielding to (null)
ACPI: acpi_idle yielding to (null)

Signed-off-by Len Brown <[email protected]>

---
 Documentation/kernel-parameters.txt |    3 +++
 drivers/cpuidle/cpuidle.c           |   10 ++++++++++
 drivers/cpuidle/cpuidle.h           |    1 +
 drivers/cpuidle/driver.c            |    3 +++
 drivers/cpuidle/governor.c          |    3 +++
 5 files changed, 20 insertions(+), 0 deletions(-)

Documentation/kernel-parameters.txt +3 -0

index f4a04c0..08e8a22 100644
@@ -546,6 +546,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			/proc/<pid>/coredump_filter.
 			See also Documentation/filesystems/proc.txt.
 
+	cpuidle.off=1	[CPU_IDLE]
+			disable the cpuidle sub-system
+
 	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
 			Format:
 			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]

drivers/cpuidle/cpuidle.c +10 -0

index bf50924..faae2c3 100644
@@ -28,6 +28,12 @@ LIST_HEAD(cpuidle_detected_devices);
 static void (*pm_idle_old)(void);
 
 static int enabled_devices;
+static int off __read_mostly;
+
+int cpuidle_disabled(void)
+{
+	return off;
+}
 
 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
 static void cpuidle_kick_cpus(void)

@@ -427,6 +433,9 @@ static int __init cpuidle_init(void)
 {
 	int ret;
 
+	if (cpuidle_disabled())
+		return -ENODEV;
+
 	pm_idle_old = pm_idle;
 
 	ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);

@@ -438,4 +447,5 @@ static int __init cpuidle_init(void)
 	return 0;
 }
 
+module_param(off, int, 0444);
 core_initcall(cpuidle_init);

drivers/cpuidle/cpuidle.h +1 -0

index 33e50d5..38c3fd8 100644
@@ -13,6 +13,7 @@ extern struct list_head cpuidle_governors;
 extern struct list_head cpuidle_detected_devices;
 extern struct mutex cpuidle_lock;
 extern spinlock_t cpuidle_driver_lock;
+extern int cpuidle_disabled(void);
 
 /* idle loop */
 extern void cpuidle_install_idle_handler(void);

drivers/cpuidle/driver.c +3 -0

index fd1601e..3f7e3ce 100644
@@ -26,6 +26,9 @@ int cpuidle_register_driver(struct cpuidle_driver *drv)
 	if (!drv)
 		return -EINVAL;
 
+	if (cpuidle_disabled())
+		return -ENODEV;
+
 	spin_lock(&cpuidle_driver_lock);
 	if (cpuidle_curr_driver) {
 		spin_unlock(&cpuidle_driver_lock);

drivers/cpuidle/governor.c +0 -0

index 724c164..ea2f8e7 100644

drivers/cpuidle/governor.c int cpuidle_register_governor(struct cpuidle_governor *gov) · line 89

Quoted 9 lines

drivers/cpuidle/governor.c +3 -0

@@ -81,6 +81,9 @@ int cpuidle_register_governor(struct cpuidle_governor *gov)
 	if (!gov || !gov->select)
 		return -EINVAL;
 
+	if (cpuidle_disabled())
+		return -ENODEV;
+
 	mutex_lock(&cpuidle_lock);
 	if (__cpuidle_find_governor(gov->name) == NULL) {
 		ret = 0;

Hi Len,
We would like to know as to when the patch that completely removes pm_idle for x86 "cpuidle: stop using pm_idle" and that which introduces bootparam cpuidle.off "cpuidle: create bootparam cpuidle.off=1" be pushed ? Are there any dependencies that needs to be addressed before queuing it up for the next merge window ? If yes, can you please let us know what the dependencies are. We need these patches for running cpuidle driver for pseries.
https://lkml.org/lkml/2011/6/7/375

Thanks
- Deepthi

Deepthi Dharwar

2011-07-15 11:28 UTC #112 lore raw

Re: [linux-pm] [PATCH 08/18] cpuidle: create bootparam "cpuidle.off=1"

In reply to Len Brown

Quoted 98 lines · Len Brown

From: Len Brown <[email protected]>

useful for disabling cpuidle to fall back
to architecture-default idle loop

cpuidle drivers and governors will fail to register. on x86 they'll say so:

intel_idle: intel_idle yielding to (null)
ACPI: acpi_idle yielding to (null)

Signed-off-by Len Brown <[email protected]>

---
 Documentation/kernel-parameters.txt |    3 +++
 drivers/cpuidle/cpuidle.c           |   10 ++++++++++
 drivers/cpuidle/cpuidle.h           |    1 +
 drivers/cpuidle/driver.c            |    3 +++
 drivers/cpuidle/governor.c          |    3 +++
 5 files changed, 20 insertions(+), 0 deletions(-)

Documentation/kernel-parameters.txt +3 -0

index f4a04c0..08e8a22 100644
@@ -546,6 +546,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			/proc/<pid>/coredump_filter.
 			See also Documentation/filesystems/proc.txt.
 
+	cpuidle.off=1	[CPU_IDLE]
+			disable the cpuidle sub-system
+
 	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
 			Format:
 			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]

drivers/cpuidle/cpuidle.c +10 -0

index bf50924..faae2c3 100644
@@ -28,6 +28,12 @@ LIST_HEAD(cpuidle_detected_devices);
 static void (*pm_idle_old)(void);
 
 static int enabled_devices;
+static int off __read_mostly;
+
+int cpuidle_disabled(void)
+{
+	return off;
+}
 
 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
 static void cpuidle_kick_cpus(void)

@@ -427,6 +433,9 @@ static int __init cpuidle_init(void)
 {
 	int ret;
 
+	if (cpuidle_disabled())
+		return -ENODEV;
+
 	pm_idle_old = pm_idle;
 
 	ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);

@@ -438,4 +447,5 @@ static int __init cpuidle_init(void)
 	return 0;
 }
 
+module_param(off, int, 0444);
 core_initcall(cpuidle_init);

drivers/cpuidle/cpuidle.h +1 -0

index 33e50d5..38c3fd8 100644
@@ -13,6 +13,7 @@ extern struct list_head cpuidle_governors;
 extern struct list_head cpuidle_detected_devices;
 extern struct mutex cpuidle_lock;
 extern spinlock_t cpuidle_driver_lock;
+extern int cpuidle_disabled(void);
 
 /* idle loop */
 extern void cpuidle_install_idle_handler(void);

drivers/cpuidle/driver.c +3 -0

index fd1601e..3f7e3ce 100644
@@ -26,6 +26,9 @@ int cpuidle_register_driver(struct cpuidle_driver *drv)
 	if (!drv)
 		return -EINVAL;
 
+	if (cpuidle_disabled())
+		return -ENODEV;
+
 	spin_lock(&cpuidle_driver_lock);
 	if (cpuidle_curr_driver) {
 		spin_unlock(&cpuidle_driver_lock);

drivers/cpuidle/governor.c +0 -0

index 724c164..ea2f8e7 100644

drivers/cpuidle/governor.c int cpuidle_register_governor(struct cpuidle_governor *gov) · line 89

Quoted 9 lines

drivers/cpuidle/governor.c +3 -0

@@ -81,6 +81,9 @@ int cpuidle_register_governor(struct cpuidle_governor *gov)
 	if (!gov || !gov->select)
 		return -EINVAL;
 
+	if (cpuidle_disabled())
+		return -ENODEV;
+
 	mutex_lock(&cpuidle_lock);
 	if (__cpuidle_find_governor(gov->name) == NULL) {
 		ret = 0;

Thanks
- Deepthi

Len Brown

author reviewer

2011-04-02 06:22 UTC #113 lore raw

PATCH 9/18 cpuidle: replace xen access to x86 pm_idle and default_idle

In reply to Len Brown

From: Len Brown <[email protected]>

When a Xen Dom0 kernel boots on a hypervisor, it gets access to the raw-hardware ACPI tables. While it parses the idle tables for the hypervisor's beneift, it uses HLT for its own idle.

Rather than have xen scribble on pm_idle and access default_idle, have it simply disable_cpuidle() so acpi_idle will not load and architecture default HLT will be used.

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/xen/setup.c      |    3 ++-
 drivers/cpuidle/cpuidle.c |    4 ++++
 include/linux/cpuidle.h   |    2 ++
 3 files changed, 8 insertions(+), 1 deletions(-)

arch/x86/xen/setup.c +2 -1

index a8a66a5..aa02cce 100644
@@ -9,6 +9,7 @@
 #include <linux/mm.h>
 #include <linux/pm.h>
 #include <linux/memblock.h>
+#include <linux/cpuidle.h>
 
 #include <asm/elf.h>
 #include <asm/vdso.h>

@@ -354,7 +355,7 @@ void __init xen_arch_setup(void)
 #ifdef CONFIG_X86_32
 	boot_cpu_data.hlt_works_ok = 1;
 #endif
-	pm_idle = default_idle;
+	disable_cpuidle();
 	boot_option_idle_override = IDLE_HALT;
 
 	fiddle_vdso();

drivers/cpuidle/cpuidle.c +4 -0

index faae2c3..041df0b 100644
@@ -34,6 +34,10 @@ int cpuidle_disabled(void)
 {
 	return off;
 }
+void disable_cpuidle(void)
+{
+	off = 1;
+}
 
 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
 static void cpuidle_kick_cpus(void)

include/linux/cpuidle.h +2 -0

index 36719ea..b89f67d 100644
@@ -122,6 +122,7 @@ struct cpuidle_driver {
 };
 
 #ifdef CONFIG_CPU_IDLE
+extern void disable_cpuidle(void);
 
 extern int cpuidle_register_driver(struct cpuidle_driver *drv);
 struct cpuidle_driver *cpuidle_get_driver(void);

@@ -135,6 +136,7 @@ extern int cpuidle_enable_device(struct cpuidle_device *dev);
 extern void cpuidle_disable_device(struct cpuidle_device *dev);
 
 #else
+static inline void disable_cpuidle(void) { }
 
 static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
 {return -ENODEV; }

Signature · 1 line

1.7.5.rc0

Konrad Rzeszutek Wilk

2011-04-04 15:33 UTC #114 lore raw

Re: [Xen-devel] [PATCH 09/18] cpuidle: replace xen access to x86 pm_idle and default_idle

Quoted 9 lines · Len Brown

From: Len Brown <[email protected]>
When a Xen Dom0 kernel boots on a hypervisor, it gets access to the raw-hardware ACPI tables. While it parses the idle tables for the hypervisor's beneift, it uses HLT for its own idle.
Rather than have xen scribble on pm_idle and access default_idle, have it simply disable_cpuidle() so acpi_idle will not load and architecture default HLT will be used.

Hey Len,

Looks good to me. I've also tested this on the affected Intel machine and your patchset works fine.

Quoted 73 lines

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/xen/setup.c      |    3 ++-
 drivers/cpuidle/cpuidle.c |    4 ++++
 include/linux/cpuidle.h   |    2 ++
 3 files changed, 8 insertions(+), 1 deletions(-)

arch/x86/xen/setup.c +2 -1

index a8a66a5..aa02cce 100644
@@ -9,6 +9,7 @@
 #include <linux/mm.h>
 #include <linux/pm.h>
 #include <linux/memblock.h>
+#include <linux/cpuidle.h>
 
 #include <asm/elf.h>
 #include <asm/vdso.h>

@@ -354,7 +355,7 @@ void __init xen_arch_setup(void)
 #ifdef CONFIG_X86_32
 	boot_cpu_data.hlt_works_ok = 1;
 #endif
-	pm_idle = default_idle;
+	disable_cpuidle();
 	boot_option_idle_override = IDLE_HALT;
 
 	fiddle_vdso();

drivers/cpuidle/cpuidle.c +4 -0

index faae2c3..041df0b 100644
@@ -34,6 +34,10 @@ int cpuidle_disabled(void)
 {
 	return off;
 }
+void disable_cpuidle(void)
+{
+	off = 1;
+}
 
 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
 static void cpuidle_kick_cpus(void)

include/linux/cpuidle.h +2 -0

index 36719ea..b89f67d 100644
@@ -122,6 +122,7 @@ struct cpuidle_driver {
 };
 
 #ifdef CONFIG_CPU_IDLE
+extern void disable_cpuidle(void);
 
 extern int cpuidle_register_driver(struct cpuidle_driver *drv);
 struct cpuidle_driver *cpuidle_get_driver(void);

@@ -135,6 +136,7 @@ extern int cpuidle_enable_device(struct cpuidle_device *dev);
 extern void cpuidle_disable_device(struct cpuidle_device *dev);
 
 #else
+static inline void disable_cpuidle(void) { }
 
 static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
 {return -ENODEV; }

Signature · 7 lines

1.7.5.rc0


_______________________________________________
Xen-devel mailing list
[email protected]
http://lists.xensource.com/xen-devel

Konrad Rzeszutek Wilk

2011-04-04 15:33 UTC #115 lore raw

Re: [Xen-devel] [PATCH 09/18] cpuidle: replace xen access to x86 pm_idle and default_idle

In reply to Len Brown

Quoted 9 lines · Len Brown

From: Len Brown <[email protected]>
When a Xen Dom0 kernel boots on a hypervisor, it gets access to the raw-hardware ACPI tables. While it parses the idle tables for the hypervisor's beneift, it uses HLT for its own idle.
Rather than have xen scribble on pm_idle and access default_idle, have it simply disable_cpuidle() so acpi_idle will not load and architecture default HLT will be used.

Hey Len,

Looks good to me. I've also tested this on the affected Intel machine and your patchset works fine.

Quoted 73 lines

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/xen/setup.c      |    3 ++-
 drivers/cpuidle/cpuidle.c |    4 ++++
 include/linux/cpuidle.h   |    2 ++
 3 files changed, 8 insertions(+), 1 deletions(-)

arch/x86/xen/setup.c +2 -1

index a8a66a5..aa02cce 100644
@@ -9,6 +9,7 @@
 #include <linux/mm.h>
 #include <linux/pm.h>
 #include <linux/memblock.h>
+#include <linux/cpuidle.h>
 
 #include <asm/elf.h>
 #include <asm/vdso.h>

@@ -354,7 +355,7 @@ void __init xen_arch_setup(void)
 #ifdef CONFIG_X86_32
 	boot_cpu_data.hlt_works_ok = 1;
 #endif
-	pm_idle = default_idle;
+	disable_cpuidle();
 	boot_option_idle_override = IDLE_HALT;
 
 	fiddle_vdso();

drivers/cpuidle/cpuidle.c +4 -0

index faae2c3..041df0b 100644
@@ -34,6 +34,10 @@ int cpuidle_disabled(void)
 {
 	return off;
 }
+void disable_cpuidle(void)
+{
+	off = 1;
+}
 
 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
 static void cpuidle_kick_cpus(void)

include/linux/cpuidle.h +2 -0

index 36719ea..b89f67d 100644
@@ -122,6 +122,7 @@ struct cpuidle_driver {
 };
 
 #ifdef CONFIG_CPU_IDLE
+extern void disable_cpuidle(void);
 
 extern int cpuidle_register_driver(struct cpuidle_driver *drv);
 struct cpuidle_driver *cpuidle_get_driver(void);

@@ -135,6 +136,7 @@ extern int cpuidle_enable_device(struct cpuidle_device *dev);
 extern void cpuidle_disable_device(struct cpuidle_device *dev);
 
 #else
+static inline void disable_cpuidle(void) { }
 
 static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
 {return -ENODEV; }

Signature · 7 lines

1.7.5.rc0


_______________________________________________
Xen-devel mailing list
[email protected]
http://lists.xensource.com/xen-devel

Len Brown

author reviewer

2011-04-02 06:22 UTC #116 lore raw

PATCH 9/18 cpuidle: replace xen access to x86 pm_idle and default_idle

In reply to Len Brown

From: Len Brown <[email protected]>

When a Xen Dom0 kernel boots on a hypervisor, it gets access to the raw-hardware ACPI tables. While it parses the idle tables for the hypervisor's beneift, it uses HLT for its own idle.

Rather than have xen scribble on pm_idle and access default_idle, have it simply disable_cpuidle() so acpi_idle will not load and architecture default HLT will be used.

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/xen/setup.c      |    3 ++-
 drivers/cpuidle/cpuidle.c |    4 ++++
 include/linux/cpuidle.h   |    2 ++
 3 files changed, 8 insertions(+), 1 deletions(-)

arch/x86/xen/setup.c +2 -1

index a8a66a5..aa02cce 100644
@@ -9,6 +9,7 @@
 #include <linux/mm.h>
 #include <linux/pm.h>
 #include <linux/memblock.h>
+#include <linux/cpuidle.h>
 
 #include <asm/elf.h>
 #include <asm/vdso.h>

@@ -354,7 +355,7 @@ void __init xen_arch_setup(void)
 #ifdef CONFIG_X86_32
 	boot_cpu_data.hlt_works_ok = 1;
 #endif
-	pm_idle = default_idle;
+	disable_cpuidle();
 	boot_option_idle_override = IDLE_HALT;
 
 	fiddle_vdso();

drivers/cpuidle/cpuidle.c +4 -0

index faae2c3..041df0b 100644
@@ -34,6 +34,10 @@ int cpuidle_disabled(void)
 {
 	return off;
 }
+void disable_cpuidle(void)
+{
+	off = 1;
+}
 
 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
 static void cpuidle_kick_cpus(void)

include/linux/cpuidle.h +2 -0

index 36719ea..b89f67d 100644
@@ -122,6 +122,7 @@ struct cpuidle_driver {
 };
 
 #ifdef CONFIG_CPU_IDLE
+extern void disable_cpuidle(void);
 
 extern int cpuidle_register_driver(struct cpuidle_driver *drv);
 struct cpuidle_driver *cpuidle_get_driver(void);

@@ -135,6 +136,7 @@ extern int cpuidle_enable_device(struct cpuidle_device *dev);
 extern void cpuidle_disable_device(struct cpuidle_device *dev);
 
 #else
+static inline void disable_cpuidle(void) { }
 
 static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
 {return -ENODEV; }

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:22 UTC #117 lore raw

PATCH 10/18 x86 idle: move mwait_idle_with_hints() to where it is used

In reply to Len Brown

From: Len Brown <[email protected]>

...and make it static

no functional change

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |    2 --
 arch/x86/kernel/acpi/cstate.c    |   24 ++++++++++++++++++++++++
 arch/x86/kernel/process.c        |   23 -----------------------
 3 files changed, 24 insertions(+), 25 deletions(-)

arch/x86/include/asm/processor.h +0 -2

index a8c5fed..fd02787 100644
@@ -755,8 +755,6 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
 		     :: "a" (eax), "c" (ecx));
 }
 
-extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
-
 extern void select_idle_routine(const struct cpuinfo_x86 *c);
 extern void init_amd_e400_mask(void);

arch/x86/kernel/acpi/cstate.c +24 -0

index 5812404..c49281e 100644
@@ -149,6 +149,30 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
 }
 EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
 
+/*
+ * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
+ * which can obviate IPI to trigger checking of need_resched.
+ * We execute MONITOR against need_resched and enter optimized wait state
+ * through MWAIT. Whenever someone changes need_resched, we would be woken
+ * up from MWAIT (without an IPI).
+ *
+ * New with Core Duo processors, MWAIT can take some hints based on CPU
+ * capability.
+ */
+static void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
+{
+	if (!need_resched()) {
+		if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
+			clflush((void *)&current_thread_info()->flags);
+
+		__monitor((void *)&current_thread_info()->flags, 0, 0);
+		smp_mb();
+		if (!need_resched())
+			__mwait(ax, cx);
+	}
+}
+
+
 void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx)
 {
 	unsigned int cpu = smp_processor_id();

arch/x86/kernel/process.c +0 ~~-23~~

index 1c45a9c..579c78f 100644
@@ -441,29 +441,6 @@ void cpu_idle_wait(void)
 }
 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 
-/*
- * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
- * which can obviate IPI to trigger checking of need_resched.
- * We execute MONITOR against need_resched and enter optimized wait state
- * through MWAIT. Whenever someone changes need_resched, we would be woken
- * up from MWAIT (without an IPI).
- *
- * New with Core Duo processors, MWAIT can take some hints based on CPU
- * capability.
- */
-void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
-{
-	if (!need_resched()) {
-		if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
-			clflush((void *)&current_thread_info()->flags);
-
-		__monitor((void *)&current_thread_info()->flags, 0, 0);
-		smp_mb();
-		if (!need_resched())
-			__mwait(ax, cx);
-	}
-}
-
 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
 static void mwait_idle(void)
 {

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:22 UTC #118 lore raw

PATCH 11/18 cpuidle: stop using pm_idle

In reply to Len Brown

From: Len Brown <[email protected]>

pm_idle does not scale as an idle handler registration mechanism. Don't use it for cpuidle. Instead, call cpuidle directly, and allow architectures to use pm_idle as an arch-specific default if they need it. ie.

cpu_idle()

	...
	if(cpuidle_call_idle())
		pm_idle();

cc [email protected]

cc Kevin Hilman <[email protected]>

cc Paul Mundt <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 arch/arm/kernel/process.c    |    4 +++-
 arch/sh/kernel/idle.c        |    6 ++++--
 arch/x86/kernel/process_32.c |    4 +++-
 arch/x86/kernel/process_64.c |    4 +++-
 drivers/cpuidle/cpuidle.c    |   38 ++++++++++++++++++--------------------
 include/linux/cpuidle.h      |    2 ++
 6 files changed, 33 insertions(+), 25 deletions(-)

arch/arm/kernel/process.c +3 -1

index 94bbedb..dc9d685 100644
@@ -30,6 +30,7 @@
 #include <linux/uaccess.h>
 #include <linux/random.h>
 #include <linux/hw_breakpoint.h>
+#include <linux/cpuidle.h>
 
 #include <asm/cacheflush.h>
 #include <asm/leds.h>

@@ -196,7 +197,8 @@ void cpu_idle(void)
 				cpu_relax();
 			} else {
 				stop_critical_timings();
-				pm_idle();
+				if (cpuidle_call_idle())
+					pm_idle();
 				start_critical_timings();
 				/*
 				 * This will eventually be removed - pm_idle

arch/sh/kernel/idle.c +4 -2

index 425d604..9c7099e 100644
@@ -16,12 +16,13 @@
 #include <linux/thread_info.h>
 #include <linux/irqflags.h>
 #include <linux/smp.h>
+#include <linux/cpuidle.h>
 #include <asm/pgalloc.h>
 #include <asm/system.h>
 #include <asm/atomic.h>
 #include <asm/smp.h>
 
-void (*pm_idle)(void) = NULL;
+static void (*pm_idle)(void);
 
 static int hlt_counter;

@@ -100,7 +101,8 @@ void cpu_idle(void)
 			local_irq_disable();
 			/* Don't trace irqs off for idle */
 			stop_critical_timings();
-			pm_idle();
+			if (cpuidle_call_idle())
+				pm_idle();
 			/*
 			 * Sanity check to ensure that pm_idle() returns
 			 * with IRQs enabled

arch/x86/kernel/process_32.c +3 -1

index 8d12878..61fadbe 100644
@@ -38,6 +38,7 @@
 #include <linux/uaccess.h>
 #include <linux/io.h>
 #include <linux/kdebug.h>
+#include <linux/cpuidle.h>
 
 #include <asm/pgtable.h>
 #include <asm/system.h>

@@ -109,7 +110,8 @@ void cpu_idle(void)
 			local_irq_disable();
 			/* Don't trace irqs off for idle */
 			stop_critical_timings();
-			pm_idle();
+			if (cpuidle_idle_call())
+				pm_idle();
 			start_critical_timings();
 		}
 		tick_nohz_restart_sched_tick();

arch/x86/kernel/process_64.c +3 -1

index bd387e8..210641a 100644
@@ -37,6 +37,7 @@
 #include <linux/uaccess.h>
 #include <linux/io.h>
 #include <linux/ftrace.h>
+#include <linux/cpuidle.h>
 
 #include <asm/pgtable.h>
 #include <asm/system.h>

@@ -136,7 +137,8 @@ void cpu_idle(void)
 			enter_idle();
 			/* Don't trace irqs off for idle */
 			stop_critical_timings();
-			pm_idle();
+			if (cpuidle_idle_call())
+				pm_idle();
 			start_critical_timings();
 
 			/* In many cases the interrupt that ended idle

drivers/cpuidle/cpuidle.c +18 ~~-20~~

index 041df0b..d4c5423 100644
@@ -25,10 +25,10 @@ DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
 
 DEFINE_MUTEX(cpuidle_lock);
 LIST_HEAD(cpuidle_detected_devices);
-static void (*pm_idle_old)(void);
 
 static int enabled_devices;
 static int off __read_mostly;
+static int initialized __read_mostly;
 
 int cpuidle_disabled(void)
 {

@@ -56,25 +56,23 @@ static int __cpuidle_register_device(struct cpuidle_device *dev);
  * cpuidle_idle_call - the main idle loop
  *
  * NOTE: no locks or semaphores should be used here
+ * return non-zero on failure
  */
-static void cpuidle_idle_call(void)
+int cpuidle_idle_call(void)
 {
 	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
 	struct cpuidle_state *target_state;
 	int next_state;
 
+	if (off)
+		return -ENODEV;
+
+	if (!initialized)
+		return -ENODEV;
+
 	/* check if the device is ready */
-	if (!dev || !dev->enabled) {
-		if (pm_idle_old)
-			pm_idle_old();
-		else
-#if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE)
-			default_idle();
-#else
-			local_irq_enable();
-#endif
-		return;
-	}
+	if (!dev || !dev->enabled)
+		return -EBUSY;
 
 #if 0
 	/* shows regressions, re-enable for 2.6.29 */

@@ -99,7 +97,7 @@ static void cpuidle_idle_call(void)
 	next_state = cpuidle_curr_governor->select(dev);
 	if (need_resched()) {
 		local_irq_enable();
-		return;
+		return 0;
 	}
 
 	target_state = &dev->states[next_state];

@@ -124,6 +122,8 @@ static void cpuidle_idle_call(void)
 	/* give the governor an opportunity to reflect on the outcome */
 	if (cpuidle_curr_governor->reflect)
 		cpuidle_curr_governor->reflect(dev);
+
+	return 0;
 }
 
 /**

@@ -131,10 +131,10 @@ static void cpuidle_idle_call(void)
  */
 void cpuidle_install_idle_handler(void)
 {
-	if (enabled_devices && (pm_idle != cpuidle_idle_call)) {
+	if (enabled_devices) {
 		/* Make sure all changes finished before we switch to new idle */
 		smp_wmb();
-		pm_idle = cpuidle_idle_call;
+		initialized = 1;
 	}
 }

@@ -143,8 +143,8 @@ void cpuidle_install_idle_handler(void)
  */
 void cpuidle_uninstall_idle_handler(void)
 {
-	if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) {
-		pm_idle = pm_idle_old;
+	if (enabled_devices) {
+		initialized = 0;
 		cpuidle_kick_cpus();
 	}
 }

@@ -440,8 +440,6 @@ static int __init cpuidle_init(void)
 	if (cpuidle_disabled())
 		return -ENODEV;
 
-	pm_idle_old = pm_idle;
-
 	ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
 	if (ret)
 		return ret;

include/linux/cpuidle.h +2 -0

index b89f67d..b51629e 100644
@@ -123,6 +123,7 @@ struct cpuidle_driver {
 
 #ifdef CONFIG_CPU_IDLE
 extern void disable_cpuidle(void);
+extern int cpuidle_idle_call(void);
 
 extern int cpuidle_register_driver(struct cpuidle_driver *drv);
 struct cpuidle_driver *cpuidle_get_driver(void);

@@ -137,6 +138,7 @@ extern void cpuidle_disable_device(struct cpuidle_device *dev);
 
 #else
 static inline void disable_cpuidle(void) { }
+static inline int cpuidle_idle_call(void) { return -ENODEV; }
 
 static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
 {return -ENODEV; }

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 07:02 UTC #119 lore raw

PATCH 11/18 cpuidle: stop using pm_idle

In reply to Len Brown

From: Len Brown <[email protected]>

cpu_idle()

	...
	if(cpuidle_call_idle())
		pm_idle();

cc [email protected]

cc Kevin Hilman <[email protected]>

cc Paul Mundt <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 arch/arm/kernel/process.c    |    4 +++-
 arch/sh/kernel/idle.c        |    6 ++++--
 arch/x86/kernel/process_32.c |    4 +++-
 arch/x86/kernel/process_64.c |    4 +++-
 drivers/cpuidle/cpuidle.c    |   38 ++++++++++++++++++--------------------
 include/linux/cpuidle.h      |    2 ++
 6 files changed, 33 insertions(+), 25 deletions(-)

arch/arm/kernel/process.c +3 -1

index 94bbedb..dc9d685 100644
@@ -30,6 +30,7 @@
 #include <linux/uaccess.h>
 #include <linux/random.h>
 #include <linux/hw_breakpoint.h>
+#include <linux/cpuidle.h>
 
 #include <asm/cacheflush.h>
 #include <asm/leds.h>

@@ -196,7 +197,8 @@ void cpu_idle(void)
 				cpu_relax();
 			} else {
 				stop_critical_timings();
-				pm_idle();
+				if (cpuidle_call_idle())
+					pm_idle();
 				start_critical_timings();
 				/*
 				 * This will eventually be removed - pm_idle

arch/sh/kernel/idle.c +4 -2

index 425d604..9c7099e 100644
@@ -16,12 +16,13 @@
 #include <linux/thread_info.h>
 #include <linux/irqflags.h>
 #include <linux/smp.h>
+#include <linux/cpuidle.h>
 #include <asm/pgalloc.h>
 #include <asm/system.h>
 #include <asm/atomic.h>
 #include <asm/smp.h>
 
-void (*pm_idle)(void) = NULL;
+static void (*pm_idle)(void);
 
 static int hlt_counter;

@@ -100,7 +101,8 @@ void cpu_idle(void)
 			local_irq_disable();
 			/* Don't trace irqs off for idle */
 			stop_critical_timings();
-			pm_idle();
+			if (cpuidle_call_idle())
+				pm_idle();
 			/*
 			 * Sanity check to ensure that pm_idle() returns
 			 * with IRQs enabled

arch/x86/kernel/process_32.c +3 -1

index 8d12878..61fadbe 100644
@@ -38,6 +38,7 @@
 #include <linux/uaccess.h>
 #include <linux/io.h>
 #include <linux/kdebug.h>
+#include <linux/cpuidle.h>
 
 #include <asm/pgtable.h>
 #include <asm/system.h>

@@ -109,7 +110,8 @@ void cpu_idle(void)
 			local_irq_disable();
 			/* Don't trace irqs off for idle */
 			stop_critical_timings();
-			pm_idle();
+			if (cpuidle_idle_call())
+				pm_idle();
 			start_critical_timings();
 		}
 		tick_nohz_restart_sched_tick();

arch/x86/kernel/process_64.c +3 -1

index bd387e8..210641a 100644
@@ -37,6 +37,7 @@
 #include <linux/uaccess.h>
 #include <linux/io.h>
 #include <linux/ftrace.h>
+#include <linux/cpuidle.h>
 
 #include <asm/pgtable.h>
 #include <asm/system.h>

@@ -136,7 +137,8 @@ void cpu_idle(void)
 			enter_idle();
 			/* Don't trace irqs off for idle */
 			stop_critical_timings();
-			pm_idle();
+			if (cpuidle_idle_call())
+				pm_idle();
 			start_critical_timings();
 
 			/* In many cases the interrupt that ended idle

drivers/cpuidle/cpuidle.c +18 ~~-20~~

index 041df0b..d4c5423 100644
@@ -25,10 +25,10 @@ DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
 
 DEFINE_MUTEX(cpuidle_lock);
 LIST_HEAD(cpuidle_detected_devices);
-static void (*pm_idle_old)(void);
 
 static int enabled_devices;
 static int off __read_mostly;
+static int initialized __read_mostly;
 
 int cpuidle_disabled(void)
 {

@@ -56,25 +56,23 @@ static int __cpuidle_register_device(struct cpuidle_device *dev);
  * cpuidle_idle_call - the main idle loop
  *
  * NOTE: no locks or semaphores should be used here
+ * return non-zero on failure
  */
-static void cpuidle_idle_call(void)
+int cpuidle_idle_call(void)
 {
 	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
 	struct cpuidle_state *target_state;
 	int next_state;
 
+	if (off)
+		return -ENODEV;
+
+	if (!initialized)
+		return -ENODEV;
+
 	/* check if the device is ready */
-	if (!dev || !dev->enabled) {
-		if (pm_idle_old)
-			pm_idle_old();
-		else
-#if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE)
-			default_idle();
-#else
-			local_irq_enable();
-#endif
-		return;
-	}
+	if (!dev || !dev->enabled)
+		return -EBUSY;
 
 #if 0
 	/* shows regressions, re-enable for 2.6.29 */

@@ -99,7 +97,7 @@ static void cpuidle_idle_call(void)
 	next_state = cpuidle_curr_governor->select(dev);
 	if (need_resched()) {
 		local_irq_enable();
-		return;
+		return 0;
 	}
 
 	target_state = &dev->states[next_state];

@@ -124,6 +122,8 @@ static void cpuidle_idle_call(void)
 	/* give the governor an opportunity to reflect on the outcome */
 	if (cpuidle_curr_governor->reflect)
 		cpuidle_curr_governor->reflect(dev);
+
+	return 0;
 }
 
 /**

@@ -131,10 +131,10 @@ static void cpuidle_idle_call(void)
  */
 void cpuidle_install_idle_handler(void)
 {
-	if (enabled_devices && (pm_idle != cpuidle_idle_call)) {
+	if (enabled_devices) {
 		/* Make sure all changes finished before we switch to new idle */
 		smp_wmb();
-		pm_idle = cpuidle_idle_call;
+		initialized = 1;
 	}
 }

@@ -143,8 +143,8 @@ void cpuidle_install_idle_handler(void)
  */
 void cpuidle_uninstall_idle_handler(void)
 {
-	if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) {
-		pm_idle = pm_idle_old;
+	if (enabled_devices) {
+		initialized = 0;
 		cpuidle_kick_cpus();
 	}
 }

@@ -440,8 +440,6 @@ static int __init cpuidle_init(void)
 	if (cpuidle_disabled())
 		return -ENODEV;
 
-	pm_idle_old = pm_idle;
-
 	ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
 	if (ret)
 		return ret;

include/linux/cpuidle.h +2 -0

index b89f67d..b51629e 100644
@@ -123,6 +123,7 @@ struct cpuidle_driver {
 
 #ifdef CONFIG_CPU_IDLE
 extern void disable_cpuidle(void);
+extern int cpuidle_idle_call(void);
 
 extern int cpuidle_register_driver(struct cpuidle_driver *drv);
 struct cpuidle_driver *cpuidle_get_driver(void);

@@ -137,6 +138,7 @@ extern void cpuidle_disable_device(struct cpuidle_device *dev);
 
 #else
 static inline void disable_cpuidle(void) { }
+static inline int cpuidle_idle_call(void) { return -ENODEV; }
 
 static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
 {return -ENODEV; }

Signature · 1 line

1.7.5.rc0

Trinabh Gupta

2011-04-25 10:41 UTC #120 lore raw

Re: [PATCH 11/18] cpuidle: stop using pm_idle

Quoted 7 lines · Len Brown

From: Len Brown<[email protected]>
pm_idle does not scale as an idle handler registration mechanism. Don't use it for cpuidle. Instead, call cpuidle directly, and allow architectures to use pm_idle as an arch-specific default if they need it. ie.

Quoted 5 lines

cpu_idle()

	...
	if(cpuidle_call_idle())
		pm_idle();

Hi Len,

This doesn't compile right now for ARM. The patch below (on top of your series) is required to compile on arm, sh

Thanks,
-Trinabh

arch/arm/kernel/process.c +1 -1

index d7ee0d4..1a347f4 100644
@@ -197,7 +197,7 @@ void cpu_idle(void)
  				cpu_relax();
  			} else {
  				stop_critical_timings();
-				if (cpuidle_call_idle())
+				if (cpuidle_idle_call())
  					pm_idle();
  				start_critical_timings();
  				/*

arch/sh/kernel/idle.c +1 -1

index 9c7099e..1db1968 100644
@@ -101,7 +101,7 @@ void cpu_idle(void)
  			local_irq_disable();
  			/* Don't trace irqs off for idle */
  			stop_critical_timings();
-			if (cpuidle_call_idle())
+			if (cpuidle_idle_call())
  				pm_idle();
  			/*
  			 * Sanity check to ensure that pm_idle() returns

Trinabh Gupta

2011-04-25 10:41 UTC #121 lore raw

Re: [linux-pm] [PATCH 11/18] cpuidle: stop using pm_idle

In reply to Len Brown

Quoted 7 lines · Len Brown

From: Len Brown<[email protected]>
pm_idle does not scale as an idle handler registration mechanism. Don't use it for cpuidle. Instead, call cpuidle directly, and allow architectures to use pm_idle as an arch-specific default if they need it. ie.

Quoted 5 lines

cpu_idle()

	...
	if(cpuidle_call_idle())
		pm_idle();

Hi Len,

This doesn't compile right now for ARM. The patch below (on top of your series) is required to compile on arm, sh

Thanks,
-Trinabh

arch/arm/kernel/process.c +1 -1

index d7ee0d4..1a347f4 100644
@@ -197,7 +197,7 @@ void cpu_idle(void)
 				cpu_relax();
 			} else {
 				stop_critical_timings();
-				if (cpuidle_call_idle())
+				if (cpuidle_idle_call())
 					pm_idle();
 				start_critical_timings();
 				/*

arch/sh/kernel/idle.c +1 -1

index 9c7099e..1db1968 100644
@@ -101,7 +101,7 @@ void cpu_idle(void)
 			local_irq_disable();
 			/* Don't trace irqs off for idle */
 			stop_critical_timings();
-			if (cpuidle_call_idle())
+			if (cpuidle_idle_call())
 				pm_idle();
 			/*
 			 * Sanity check to ensure that pm_idle() returns

Len Brown

author reviewer

2011-04-02 06:22 UTC #122 lore raw

PATCH 12/18 2.6.40: x86 idle: remove deprecated "no-hlt" cmdline param

In reply to Len Brown

From: Len Brown <[email protected]>

The X86_32-only "no-hlt" cmdline option was used to disable the HLT instruction in the idle loop for the beneift of systems with flakey power issues 15 years ago.

It would also set the "hlt_bug" line in /proc/cpuinfo and disable HLT in machine_halt().

If such a system is still running the upstream kernel, "idle=poll" is available to disable HLT in the idle loop. The kernel will, however, still use HLT in machine_halt().

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |   11 -----------
 Documentation/kernel-parameters.txt        |    4 ----
 arch/x86/kernel/cpu/bugs.c                 |    9 ---------
 3 files changed, 0 insertions(+), 24 deletions(-)

Documentation/feature-removal-schedule.txt +0 ~~-11~~

index 9ee4a2c..720e698 100644
@@ -24,17 +24,6 @@ Who:	Len Brown <[email protected]>
 
 ----------------------------
 
-What:	x86_32 "no-hlt" cmdline param
-When:	2.6.40
-Why:	remove a branch from idle path, simplify code used by everybody.
-	This option disabled the use of HLT in idle and machine_halt()
-	for hardware that was flakey 15-years ago.  Today we have
-	"idle=poll" that removed HLT from idle, and so if such a machine
-	is still running the upstream kernel, "idle=poll" is likely sufficient.
-Who:	Len Brown <[email protected]>
-
-----------------------------
-
 What:	x86 "idle=mwait" cmdline param
 When:	2.6.40
 Why:	simplify x86 idle code

Documentation/kernel-parameters.txt +0 -4

index 08e8a22..a9db94e 100644
@@ -1669,10 +1669,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			wfi(ARM) instruction doesn't work correctly and not to
 			use it. This is also useful when using JTAG debugger.
 
-	no-hlt		[BUGS=X86-32] Tells the kernel that the hlt
-			instruction doesn't work correctly and not to
-			use it.
-
 	no_file_caps	Tells the kernel not to honor file capabilities.  The
 			only way then for a file to be executed with privilege
 			is to be setuid root or executed by root.

arch/x86/kernel/cpu/bugs.c +0 -9

index 525514c..4c91631 100644
@@ -17,15 +17,6 @@
 #include <asm/paravirt.h>
 #include <asm/alternative.h>
 
-static int __init no_halt(char *s)
-{
-	WARN_ONCE(1, "\"no-hlt\" is deprecated, please use \"idle=poll\"\n");
-	boot_cpu_data.hlt_works_ok = 0;
-	return 1;
-}
-
-__setup("no-hlt", no_halt);
-
 static int __init no_387(char *s)
 {
 	boot_cpu_data.hard_math = 0;

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:22 UTC #123 lore raw

PATCH 13/18 2.6.40: x86 idle: remove deprecated "hlt_bug: no" in 32-bit /proc/cpuinfo

In reply to Len Brown

From: Len Brown <[email protected]>

Now that the "no-hlt" cmdline param is gone...

cpuinfo_x86.hlt_works_ok, halt_works() and the "hlt_bug: no" line in 32-bit /proc/cpuinfo are NOPS.

remove them.

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |   10 ----------
 arch/x86/kernel/cpu/bugs.c       |    5 +----
 arch/x86/kernel/cpu/proc.c       |    2 --
 arch/x86/kernel/process.c        |    5 ++---
 arch/x86/kernel/setup.c          |    4 ++--
 arch/x86/xen/setup.c             |    3 ---
 6 files changed, 5 insertions(+), 24 deletions(-)

arch/x86/include/asm/processor.h +0 ~~-10~~

index fd02787..10cdee8 100644
@@ -67,7 +67,6 @@ struct cpuinfo_x86 {
 	char			wp_works_ok;	/* It doesn't on 386's */
 
 	/* Problems on some 486Dx4's and old 386's: */
-	char			hlt_works_ok;
 	char			hard_math;
 	char			rfu;
 	char			fdiv_bug;

@@ -148,15 +147,6 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
 
 extern const struct seq_operations cpuinfo_op;
 
-static inline int hlt_works(int cpu)
-{
-#ifdef CONFIG_X86_32
-	return cpu_data(cpu).hlt_works_ok;
-#else
-	return 1;
-#endif
-}
-
 #define cache_line_size()	(boot_cpu_data.x86_cache_alignment)
 
 extern void cpu_detect(struct cpuinfo_x86 *c);

arch/x86/kernel/cpu/bugs.c +1 -4

index 4c91631..b5e2910 100644
@@ -82,10 +82,7 @@ static void __init check_hlt(void)
 		return;
 
 	printk(KERN_INFO "Checking 'hlt' instruction... ");
-	if (!boot_cpu_data.hlt_works_ok) {
-		printk("disabled\n");
-		return;
-	}
+
 	halt();
 	halt();
 	halt();

arch/x86/kernel/cpu/proc.c +0 -2

index 62ac8cb..203feb7 100644
@@ -33,7 +33,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 	int fpu_exception = c->hard_math && (ignore_fpu_irq || cpu_has_fpu);
 	seq_printf(m,
 		   "fdiv_bug\t: %s\n"
-		   "hlt_bug\t\t: %s\n"
 		   "f00f_bug\t: %s\n"
 		   "coma_bug\t: %s\n"
 		   "fpu\t\t: %s\n"

@@ -41,7 +40,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 		   "cpuid level\t: %d\n"
 		   "wp\t\t: %s\n",
 		   c->fdiv_bug ? "yes" : "no",
-		   c->hlt_works_ok ? "no" : "yes",
 		   c->f00f_bug ? "yes" : "no",
 		   c->coma_bug ? "yes" : "no",
 		   c->hard_math ? "yes" : "no",

arch/x86/kernel/process.c +2 -3

index 579c78f..c485629 100644
@@ -364,7 +364,7 @@ EXPORT_SYMBOL(enable_hlt);
 
 static inline int hlt_use_halt(void)
 {
-	return (!hlt_counter && boot_cpu_data.hlt_works_ok);
+	return !hlt_counter;
 }
 #else
 static inline int hlt_use_halt(void)

@@ -416,8 +416,7 @@ void stop_this_cpu(void *dummy)
 	disable_local_APIC();
 
 	for (;;) {
-		if (hlt_works(smp_processor_id()))
-			halt();
+		halt();
 	}
 }

arch/x86/kernel/setup.c +2 -2

index d3cfe26..fab5631 100644
@@ -175,9 +175,9 @@ static struct resource bss_resource = {
 
 #ifdef CONFIG_X86_32
 /* cpu data as detected by the assembly code in head.S */
-struct cpuinfo_x86 new_cpu_data __cpuinitdata = {0, 0, 0, 0, -1, 1, 0, 0, -1};
+struct cpuinfo_x86 new_cpu_data __cpuinitdata = {0, 0, 0, 0, -1, 0, 0, -1};
 /* common cpu data for all cpus */
-struct cpuinfo_x86 boot_cpu_data __read_mostly = {0, 0, 0, 0, -1, 1, 0, 0, -1};
+struct cpuinfo_x86 boot_cpu_data __read_mostly = {0, 0, 0, 0, -1, 0, 0, -1};
 EXPORT_SYMBOL(boot_cpu_data);
 static void set_mca_bus(int x)
 {

arch/x86/xen/setup.c +0 -3

index aa02cce..32069fb 100644
@@ -352,9 +352,6 @@ void __init xen_arch_setup(void)
 	       COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);
 
 	/* Set up idle, making sure it calls safe_halt() pvop */
-#ifdef CONFIG_X86_32
-	boot_cpu_data.hlt_works_ok = 1;
-#endif
 	disable_cpuidle();
 	boot_option_idle_override = IDLE_HALT;

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 07:02 UTC #124 lore raw

PATCH 13/18 2.6.40: x86 idle: remove deprecated "hlt_bug: no" in 32-bit /proc/cpuinfo

In reply to Len Brown

From: Len Brown <[email protected]>

Now that the "no-hlt" cmdline param is gone...

cpuinfo_x86.hlt_works_ok, halt_works() and the "hlt_bug: no" line in 32-bit /proc/cpuinfo are NOPS.

remove them.

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/processor.h |   10 ----------
 arch/x86/kernel/cpu/bugs.c       |    5 +----
 arch/x86/kernel/cpu/proc.c       |    2 --
 arch/x86/kernel/process.c        |    5 ++---
 arch/x86/kernel/setup.c          |    4 ++--
 arch/x86/xen/setup.c             |    3 ---
 6 files changed, 5 insertions(+), 24 deletions(-)

arch/x86/include/asm/processor.h +0 ~~-10~~

index fd02787..10cdee8 100644
@@ -67,7 +67,6 @@ struct cpuinfo_x86 {
 	char			wp_works_ok;	/* It doesn't on 386's */
 
 	/* Problems on some 486Dx4's and old 386's: */
-	char			hlt_works_ok;
 	char			hard_math;
 	char			rfu;
 	char			fdiv_bug;

@@ -148,15 +147,6 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
 
 extern const struct seq_operations cpuinfo_op;
 
-static inline int hlt_works(int cpu)
-{
-#ifdef CONFIG_X86_32
-	return cpu_data(cpu).hlt_works_ok;
-#else
-	return 1;
-#endif
-}
-
 #define cache_line_size()	(boot_cpu_data.x86_cache_alignment)
 
 extern void cpu_detect(struct cpuinfo_x86 *c);

arch/x86/kernel/cpu/bugs.c +1 -4

index 4c91631..b5e2910 100644
@@ -82,10 +82,7 @@ static void __init check_hlt(void)
 		return;
 
 	printk(KERN_INFO "Checking 'hlt' instruction... ");
-	if (!boot_cpu_data.hlt_works_ok) {
-		printk("disabled\n");
-		return;
-	}
+
 	halt();
 	halt();
 	halt();

arch/x86/kernel/cpu/proc.c +0 -2

index 62ac8cb..203feb7 100644
@@ -33,7 +33,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 	int fpu_exception = c->hard_math && (ignore_fpu_irq || cpu_has_fpu);
 	seq_printf(m,
 		   "fdiv_bug\t: %s\n"
-		   "hlt_bug\t\t: %s\n"
 		   "f00f_bug\t: %s\n"
 		   "coma_bug\t: %s\n"
 		   "fpu\t\t: %s\n"

@@ -41,7 +40,6 @@ static void show_cpuinfo_misc(struct seq_file *m, struct cpuinfo_x86 *c)
 		   "cpuid level\t: %d\n"
 		   "wp\t\t: %s\n",
 		   c->fdiv_bug ? "yes" : "no",
-		   c->hlt_works_ok ? "no" : "yes",
 		   c->f00f_bug ? "yes" : "no",
 		   c->coma_bug ? "yes" : "no",
 		   c->hard_math ? "yes" : "no",

arch/x86/kernel/process.c +2 -3

index 579c78f..c485629 100644
@@ -364,7 +364,7 @@ EXPORT_SYMBOL(enable_hlt);
 
 static inline int hlt_use_halt(void)
 {
-	return (!hlt_counter && boot_cpu_data.hlt_works_ok);
+	return !hlt_counter;
 }
 #else
 static inline int hlt_use_halt(void)

@@ -416,8 +416,7 @@ void stop_this_cpu(void *dummy)
 	disable_local_APIC();
 
 	for (;;) {
-		if (hlt_works(smp_processor_id()))
-			halt();
+		halt();
 	}
 }

arch/x86/kernel/setup.c +2 -2

index d3cfe26..fab5631 100644
@@ -175,9 +175,9 @@ static struct resource bss_resource = {
 
 #ifdef CONFIG_X86_32
 /* cpu data as detected by the assembly code in head.S */
-struct cpuinfo_x86 new_cpu_data __cpuinitdata = {0, 0, 0, 0, -1, 1, 0, 0, -1};
+struct cpuinfo_x86 new_cpu_data __cpuinitdata = {0, 0, 0, 0, -1, 0, 0, -1};
 /* common cpu data for all cpus */
-struct cpuinfo_x86 boot_cpu_data __read_mostly = {0, 0, 0, 0, -1, 1, 0, 0, -1};
+struct cpuinfo_x86 boot_cpu_data __read_mostly = {0, 0, 0, 0, -1, 0, 0, -1};
 EXPORT_SYMBOL(boot_cpu_data);
 static void set_mca_bus(int x)
 {

arch/x86/xen/setup.c +0 -3

index aa02cce..32069fb 100644
@@ -352,9 +352,6 @@ void __init xen_arch_setup(void)
 	       COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);
 
 	/* Set up idle, making sure it calls safe_halt() pvop */
-#ifdef CONFIG_X86_32
-	boot_cpu_data.hlt_works_ok = 1;
-#endif
 	disable_cpuidle();
 	boot_option_idle_override = IDLE_HALT;

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:22 UTC #125 lore raw

PATCH 14/18 2.6.40: x86 idle floppy: remove deprecated disable_hlt()/enable_hlt()

In reply to Len Brown

From: Len Brown <[email protected]>

The X86_32-only disable_hlt/enable_hlt mechanism was used by the 32-bit floppy driver. Its effect was to replace the use of the HLT instruction inside default_idle() with cpu_relax().

This workaround was commented:
"disable hlt during certain critical i/o operations"

"This halt magic was a workaround for ancient floppy DMA
wreckage. It should be safe to remove."

Remove the workaround to simplify the idle loop.

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |    8 ------
 arch/x86/include/asm/system.h              |    7 -----
 arch/x86/kernel/process.c                  |   24 ------------------
 drivers/block/floppy.c                     |   36 ----------------------------
 4 files changed, 0 insertions(+), 75 deletions(-)

Documentation/feature-removal-schedule.txt +0 -8

index 720e698..e1e9bf8 100644
@@ -6,14 +6,6 @@ be removed from this file.
 
 ---------------------------
 
-What:	x86 floppy disable_hlt
-When:	2.6.40
-Why:	ancient workaround of dubious utility clutters the
-	code used by everybody else.
-Who:	Len Brown <[email protected]>
-
----------------------------
-
 What:	CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
 When:	2.6.40
 Why:	This optional sub-feature of APM is of dubious reliability,

arch/x86/include/asm/system.h +0 -7

index 33ecc3e..013dd42 100644
@@ -93,10 +93,6 @@ do {									\
 			"memory");					\
 } while (0)
 
-/*
- * disable hlt during certain critical i/o operations
- */
-#define HAVE_DISABLE_HLT
 #else
 #define __SAVE(reg, offset) "movq %%" #reg ",(14-" #offset ")*8(%%rsp)\n\t"
 #define __RESTORE(reg, offset) "movq (14-" #offset ")*8(%%rsp),%%" #reg "\n\t"

@@ -337,9 +333,6 @@ static inline void clflush(volatile void *__p)
 
 #define nop() asm volatile ("nop")
 
-void disable_hlt(void);
-void enable_hlt(void);
-
 void cpu_idle_wait(void);
 
 extern unsigned long arch_align_stack(unsigned long sp);

arch/x86/kernel/process.c +0 ~~-24~~

index c485629..09bd118 100644
@@ -344,34 +344,10 @@ void (*pm_idle)(void);
 EXPORT_SYMBOL(pm_idle);
 #endif
 
-#ifdef CONFIG_X86_32
-/*
- * This halt magic was a workaround for ancient floppy DMA
- * wreckage. It should be safe to remove.
- */
-static int hlt_counter;
-void disable_hlt(void)
-{
-	hlt_counter++;
-}
-EXPORT_SYMBOL(disable_hlt);
-
-void enable_hlt(void)
-{
-	hlt_counter--;
-}
-EXPORT_SYMBOL(enable_hlt);
-
-static inline int hlt_use_halt(void)
-{
-	return !hlt_counter;
-}
-#else
 static inline int hlt_use_halt(void)
 {
 	return 1;
 }
-#endif
 
 /*
  * We use this if we don't have any better

drivers/block/floppy.c +0 ~~-36~~

index 41ea03f..9a4e006 100644
@@ -1032,37 +1032,6 @@ static int fd_wait_for_completion(unsigned long delay, timeout_fn function)
 	return 0;
 }
 
-static DEFINE_SPINLOCK(floppy_hlt_lock);
-static int hlt_disabled;
-static void floppy_disable_hlt(void)
-{
-	unsigned long flags;
-
-	WARN_ONCE(1, "floppy_disable_hlt() scheduled for removal in 2.6.40");
-	spin_lock_irqsave(&floppy_hlt_lock, flags);
-	if (!hlt_disabled) {
-		hlt_disabled = 1;
-#ifdef HAVE_DISABLE_HLT
-		disable_hlt();
-#endif
-	}
-	spin_unlock_irqrestore(&floppy_hlt_lock, flags);
-}
-
-static void floppy_enable_hlt(void)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&floppy_hlt_lock, flags);
-	if (hlt_disabled) {
-		hlt_disabled = 0;
-#ifdef HAVE_DISABLE_HLT
-		enable_hlt();
-#endif
-	}
-	spin_unlock_irqrestore(&floppy_hlt_lock, flags);
-}
-
 static void setup_DMA(void)
 {
 	unsigned long f;

@@ -1107,7 +1076,6 @@ static void setup_DMA(void)
 	fd_enable_dma();
 	release_dma_lock(f);
 #endif
-	floppy_disable_hlt();
 }
 
 static void show_floppy(void);

@@ -1709,7 +1677,6 @@ irqreturn_t floppy_interrupt(int irq, void *dev_id)
 	fd_disable_dma();
 	release_dma_lock(f);
 
-	floppy_enable_hlt();
 	do_floppy = NULL;
 	if (fdc >= N_FDC || FDCS->address == -1) {
 		/* we don't even know which FDC is the culprit */

@@ -1858,8 +1825,6 @@ static void floppy_shutdown(unsigned long data)
 		show_floppy();
 	cancel_activity();
 
-	floppy_enable_hlt();
-
 	flags = claim_dma_lock();
 	fd_disable_dma();
 	release_dma_lock(flags);

@@ -4504,7 +4469,6 @@ static void floppy_release_irq_and_dma(void)
 #if N_FDC > 1
 	set_dor(1, ~8, 0);
 #endif
-	floppy_enable_hlt();
 
 	if (floppy_track_buffer && max_buffer_sectors) {
 		tmpsize = max_buffer_sectors * 1024;

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:22 UTC #126 lore raw

PATCH 15/18 2.6.40: x86 idle: remove deprecated hlt_use_halt()

In reply to Len Brown

From: Len Brown <[email protected]>

Removing the floppy workaround made hlt_use_halt() constant. So we can now remove it, and we no longer need to test it in default_idle().

no functional change.

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/kernel/process.c |   39 ++++++++++++++-------------------------
 1 files changed, 14 insertions(+), 25 deletions(-)

arch/x86/kernel/process.c +14 ~~-25~~

index 09bd118..53fb569 100644
@@ -344,39 +344,28 @@ void (*pm_idle)(void);
 EXPORT_SYMBOL(pm_idle);
 #endif
 
-static inline int hlt_use_halt(void)
-{
-	return 1;
-}
-
 /*
  * We use this if we don't have any better
  * idle routine..
  */
 void default_idle(void)
 {
-	if (hlt_use_halt()) {
-		trace_power_start(POWER_CSTATE, 1, smp_processor_id());
-		trace_cpu_idle(1, smp_processor_id());
-		current_thread_info()->status &= ~TS_POLLING;
-		/*
-		 * TS_POLLING-cleared state must be visible before we
-		 * test NEED_RESCHED:
-		 */
-		smp_mb();
+	trace_power_start(POWER_CSTATE, 1, smp_processor_id());
+	trace_cpu_idle(1, smp_processor_id());
+	current_thread_info()->status &= ~TS_POLLING;
+	/*
+	 * TS_POLLING-cleared state must be visible before we
+	 * test NEED_RESCHED:
+	 */
+	smp_mb();
 
-		if (!need_resched())
-			safe_halt();	/* enables interrupts racelessly */
-		else
-			local_irq_enable();
-		current_thread_info()->status |= TS_POLLING;
-		trace_power_end(smp_processor_id());
-		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
-	} else {
+	if (!need_resched())
+		safe_halt();	/* enables interrupts racelessly */
+	else
 		local_irq_enable();
-		/* loop is done by the caller */
-		cpu_relax();
-	}
+	current_thread_info()->status |= TS_POLLING;
+	trace_power_end(smp_processor_id());
+	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
 }
 #if defined(CONFIG_APM_MODULE) && defined(CONFIG_APM_CPU_IDLE)
 EXPORT_SYMBOL(default_idle);

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:22 UTC #127 lore raw

PATCH 16/18 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle()

In reply to Len Brown

From: Len Brown <[email protected]>

After this patch, systems running in APM mode will simply run default_idle() and HALT without calling into the BIOS from their idle loop.

This deletes modular use use of (pm_idle)() and default_idle().

Acked-by Ingo Molnar <[email protected]>

Acked-by Jiri Kosina <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |   10 --
 arch/x86/Kconfig                           |   11 --
 arch/x86/kernel/apm_32.c                   |  234 ----------------------------
 3 files changed, 0 insertions(+), 255 deletions(-)

Documentation/feature-removal-schedule.txt +0 ~~-10~~

index e1e9bf8..9b84b1a 100644
@@ -4,16 +4,6 @@ exactly is going away, why it is happening, and who is going to be doing
 the work.  When the feature is removed from the kernel, it should also
 be removed from this file.
 
----------------------------
-
-What:	CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
-When:	2.6.40
-Why:	This optional sub-feature of APM is of dubious reliability,
-	and ancient APM laptops are likely better served by calling HLT.
-	Deleting CONFIG_APM_CPU_IDLE allows x86 to stop exporting
-	the pm_idle function pointer to modules.
-Who:	Len Brown <[email protected]>
-
 ----------------------------
 
 What:	x86 "idle=mwait" cmdline param

arch/x86/Kconfig +0 ~~-11~~

index d5ed94d..681bb25 100644
@@ -1809,17 +1809,6 @@ config APM_DO_ENABLE
 	  T400CDT. This is off by default since most machines do fine without
 	  this feature.
 
-config APM_CPU_IDLE
-	bool "Make CPU Idle calls when idle"
-	---help---
-	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
-	  On some machines, this can activate improved power savings, such as
-	  a slowed CPU clock rate, when the machine is idle. These idle calls
-	  are made after the idle loop has run for some length of time (e.g.,
-	  333 mS). On some machines, this will cause a hang at boot time or
-	  whenever the CPU becomes idle. (On machines with more than one CPU,
-	  this option does nothing.)
-
 config APM_DISPLAY_BLANK
 	bool "Enable console blanking using APM"
 	---help---

arch/x86/kernel/apm_32.c +0 ~~-234~~

306 lines not on this page · raw message

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 07:01 UTC #128 lore raw

PATCH 16/18 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle()

In reply to Len Brown

From: Len Brown <[email protected]>

After this patch, systems running in APM mode will simply run default_idle() and HALT without calling into the BIOS from their idle loop.

This deletes modular use use of (pm_idle)() and default_idle().

Acked-by Ingo Molnar <[email protected]>

Acked-by Jiri Kosina <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |   10 --
 arch/x86/Kconfig                           |   11 --
 arch/x86/kernel/apm_32.c                   |  234 ----------------------------
 3 files changed, 0 insertions(+), 255 deletions(-)

Documentation/feature-removal-schedule.txt +0 ~~-10~~

index e1e9bf8..9b84b1a 100644
@@ -4,16 +4,6 @@ exactly is going away, why it is happening, and who is going to be doing
 the work.  When the feature is removed from the kernel, it should also
 be removed from this file.
 
----------------------------
-
-What:	CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
-When:	2.6.40
-Why:	This optional sub-feature of APM is of dubious reliability,
-	and ancient APM laptops are likely better served by calling HLT.
-	Deleting CONFIG_APM_CPU_IDLE allows x86 to stop exporting
-	the pm_idle function pointer to modules.
-Who:	Len Brown <[email protected]>
-
 ----------------------------
 
 What:	x86 "idle=mwait" cmdline param

arch/x86/Kconfig +0 ~~-11~~

index d5ed94d..681bb25 100644
@@ -1809,17 +1809,6 @@ config APM_DO_ENABLE
 	  T400CDT. This is off by default since most machines do fine without
 	  this feature.
 
-config APM_CPU_IDLE
-	bool "Make CPU Idle calls when idle"
-	---help---
-	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
-	  On some machines, this can activate improved power savings, such as
-	  a slowed CPU clock rate, when the machine is idle. These idle calls
-	  are made after the idle loop has run for some length of time (e.g.,
-	  333 mS). On some machines, this will cause a hang at boot time or
-	  whenever the CPU becomes idle. (On machines with more than one CPU,
-	  this option does nothing.)
-
 config APM_DISPLAY_BLANK
 	bool "Enable console blanking using APM"
 	---help---

arch/x86/kernel/apm_32.c +0 ~~-234~~

306 lines not on this page · raw message

Signature · 1 line

1.7.5.rc0

Alan Cox

2011-04-02 11:40 UTC #129 lore raw

Re: [PATCH 16/18] 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle()

Quoted 5 lines · On Sat, 02 Apr 2011 02:22:58 -0400 Len Brown <[email protected]> wrote:

From: Len Brown <[email protected]>
There is some doubt whether the APM idle feature to call into the BIOS from the idle loop is reliable. Certainly it was known to fail on some machines,

And it was known to work on lots - a point that despite repeated reminding you seem keen to ignore.

The fundamental problem I have with this patch set is this

You've provided no architectural overall justification for all this effort. What is the big picture around your crusade here ? What is the grand plan ?

Quoted 3 lines

but more importantly, APM machines have not shipped for a decade and so finding machines to test the code is problematic.

So don't test it - if it's wrong someone will let you know, believe me 8)

And 2.6.40 is far too soon - it takes about a year for stuff to rattle through to leading edge distro users in bulk

Alan

Len Brown

author reviewer

2011-04-02 19:44 UTC #130 lore raw

Re: [PATCH 16/18] 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle()

Quoted 4 lines

Quoted 3 lines
There is some doubt whether the APM idle feature to call into the BIOS from the idle loop is reliable. Certainly it was known to fail on some machines,

Quoted 8 lines

And it was known to work on lots - a point that despite repeated reminding you seem keen to ignore.
The fundamental problem I have with this patch set is this
You've provided no architectural overall justification for all this effort. What is the big picture around your crusade here ? What is the grand plan ?

This patch series was posted in reply to a table of contents

https://lkml.org/lkml/2011/4/2/8

"By the end of this series, pm_idle is removed as a public
x86 idle-loop registration mechanism. A few other things are cleaned up in the process."

I labeled it "idle cleanup - v3" -- I'm sorry if it went un-noticed because I neglected to put the [PATCH 0/18] on it.

Trinabh also replied to you, pointing one of the previous LKML discussions about the mis-use of pm_idle.

Quoted 8 lines

Quoted 3 lines
but more importantly, APM machines have not shipped for a decade and so finding machines to test the code is problematic.
So don't test it - if it's wrong someone will let you know, believe me 8)
And 2.6.40 is far too soon - it takes about a year for stuff to rattle through to leading edge distro users in bulk

If you insist.

We'll create a new APM cpuidle driver in Linux (Trinabh prototyped one), and at the same time, schedule it for removal in a year. Personally, I think it is make-work, and in real-life it is more likely to do more harm than removing apm_idle, but I don't want to stand in the way of process.

thanks,
-Len

Len Brown

author reviewer

2011-04-02 19:44 UTC #131 lore raw

Re: [PATCH 16/18] 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle()

In reply to Alan Cox

Quoted 4 lines

Quoted 3 lines
There is some doubt whether the APM idle feature to call into the BIOS from the idle loop is reliable. Certainly it was known to fail on some machines,

Quoted 8 lines

And it was known to work on lots - a point that despite repeated reminding you seem keen to ignore.
The fundamental problem I have with this patch set is this
You've provided no architectural overall justification for all this effort. What is the big picture around your crusade here ? What is the grand plan ?

This patch series was posted in reply to a table of contents

https://lkml.org/lkml/2011/4/2/8

"By the end of this series, pm_idle is removed as a public
x86 idle-loop registration mechanism. A few other things are cleaned up in the process."

I labeled it "idle cleanup - v3" -- I'm sorry if it went un-noticed because I neglected to put the [PATCH 0/18] on it.

Trinabh also replied to you, pointing one of the previous LKML discussions about the mis-use of pm_idle.

Quoted 8 lines

Quoted 3 lines
but more importantly, APM machines have not shipped for a decade and so finding machines to test the code is problematic.
So don't test it - if it's wrong someone will let you know, believe me 8)
And 2.6.40 is far too soon - it takes about a year for stuff to rattle through to leading edge distro users in bulk

If you insist.

thanks,
-Len

Alan Cox

2011-04-02 21:00 UTC #132 lore raw

Re: [PATCH 16/18] 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle()

Quoted 7 lines

This patch series was posted in reply to a table of contents
https://lkml.org/lkml/2011/4/2/8
"By the end of this series, pm_idle is removed as a public
x86 idle-loop registration mechanism. A few other things are cleaned up in the process."

Ok so lets rewind a bit - why do we want to remove pm_idle rather than just fix up the way registration occurs. It's just a symbol, one trivial interface that is exported and perhaps wants the export method tidying up.

Quoted 2 lines

Trinabh also replied to you, pointing one of the previous LKML discussions about the mis-use of pm_idle.

And there are misuses of just about every kernel symbol - kmalloc for example causes some people a lot of trouble !

Quoted 5 lines

We'll create a new APM cpuidle driver in Linux (Trinabh prototyped one), and at the same time, schedule it for removal in a year. Personally, I think it is make-work, and in real-life it is more likely to do more harm than removing apm_idle, but I don't want to stand in the way of process.

So you could just leave it alone - that's less work, less disruption and doesn't do any harm at all.

As I read this the plan at the moment otherwise is

- churn up all the code
- remove PM idle hook
- rewrite the APM code
- replace the APM code

whereas you could just leave the symbol exported or even just a hook to make people to do it right using:

	int register_pm_idle(function);

Simples yes ?

and then wait a year

For that matter instead of writing a new driver you could just stuff APM into same hooks we have for virtualisation !

This whole patch series appears to be a giant piece of pointless makework.

Alan

Trinabh Gupta

2011-04-03 02:48 UTC #133 lore raw

Re: [PATCH 16/18] 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle()

Quoted 12 lines · Alan Cox

Quoted 7 lines
This patch series was posted in reply to a table of contents
https://lkml.org/lkml/2011/4/2/8
"By the end of this series, pm_idle is removed as a public
x86 idle-loop registration mechanism. A few other things are cleaned up in the process."
Ok so lets rewind a bit - why do we want to remove pm_idle rather than just fix up the way registration occurs. It's just a symbol, one trivial interface that is exported and perhaps wants the export method tidying up.

Quoted 5 lines

Quoted 2 lines
Trinabh also replied to you, pointing one of the previous LKML discussions about the mis-use of pm_idle.
And there are misuses of just about every kernel symbol - kmalloc for example causes some people a lot of trouble !

There are other problems too. This design of pm_idle has been copied by numerous other architectures. arm/blackfin/cris/ia64/m32r/m68knomm /microblaze/mn10300/sh/sparc all have pm_idle. This will keep spreading in future I guess.

Quoted 17 lines

Quoted 6 lines
We'll create a new APM cpuidle driver in Linux (Trinabh prototyped one), and at the same time, schedule it for removal in a year. Personally, I think it is make-work, and in real-life it is more likely to do more harm than removing apm_idle, but I don't want to stand in the way of process.
So you could just leave it alone - that's less work, less disruption and doesn't do any harm at all.
As I read this the plan at the moment otherwise is
- churn up all the code
- remove PM idle hook
- rewrite the APM code
- replace the APM code

Quoted 4 lines

whereas you could just leave the symbol exported or even just a hook to make people to do it right using:
	int register_pm_idle(function);

A patch was posted to do exactly this; see
https://lkml.org/lkml/2010/10/19/449 . The problem is that it results in two places of registration: cpuidle subsystem and this. It was pointed that 99.99% of people run cpuidle and we should directly call cpuidle and use its registration mechanism rather than duplicate code.

Thanks,
-Trinabh

Trinabh Gupta

2011-04-03 02:49 UTC #134 lore raw

Re: [linux-pm] [PATCH 16/18] 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle()

In reply to Alan Cox

Quoted 12 lines · Alan Cox

Quoted 7 lines
This patch series was posted in reply to a table of contents
https://lkml.org/lkml/2011/4/2/8
"By the end of this series, pm_idle is removed as a public
x86 idle-loop registration mechanism. A few other things are cleaned up in the process."
Ok so lets rewind a bit - why do we want to remove pm_idle rather than just fix up the way registration occurs. It's just a symbol, one trivial interface that is exported and perhaps wants the export method tidying up.

Quoted 5 lines

Quoted 2 lines
Trinabh also replied to you, pointing one of the previous LKML discussions about the mis-use of pm_idle.
And there are misuses of just about every kernel symbol - kmalloc for example causes some people a lot of trouble !

Quoted 17 lines

Quoted 6 lines
We'll create a new APM cpuidle driver in Linux (Trinabh prototyped one), and at the same time, schedule it for removal in a year. Personally, I think it is make-work, and in real-life it is more likely to do more harm than removing apm_idle, but I don't want to stand in the way of process.
So you could just leave it alone - that's less work, less disruption and doesn't do any harm at all.
As I read this the plan at the moment otherwise is
- churn up all the code
- remove PM idle hook
- rewrite the APM code
- replace the APM code

Quoted 4 lines

whereas you could just leave the symbol exported or even just a hook to make people to do it right using:
	int register_pm_idle(function);

Thanks,
-Trinabh

Alan Cox

2011-04-04 10:05 UTC #135 lore raw

Re: [linux-pm] [PATCH 16/18] 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle()

Quoted 4 lines

There are other problems too. This design of pm_idle has been copied by numerous other architectures. arm/blackfin/cris/ia64/m32r/m68knomm /microblaze/mn10300/sh/sparc all have pm_idle. This will keep spreading in future I guess.

Presumably because they've decided it is a good model and works for them. That's a matter for their arch maintainers surely.

Quoted 5 lines

https://lkml.org/lkml/2010/10/19/449 . The problem is that it results in two places of registration: cpuidle subsystem and this. It was pointed that 99.99% of people run cpuidle and we should directly call cpuidle and use its registration mechanism rather than duplicate code.

That makes sense. However what Len is trying to do doesn't seem to.

The most likely case is nobody really needs APM idle now. In which case Len's first patches (adding the warnings) make sense, but instead of rushing headlong into everything else a simple years wait until the WARNs have been in Fedora and co for a few months would avoid any further work on it. In the mean time it produces a WARN, it can even be marked __deprecated to ensure nobody else uses it.

The less likely case is that at some point within the year it turns out a few people do need and care about it, so it needs shuffling into cpuidle nicely.

In computing terms this seems to be a lazy evaluation problem - why do all the extra work and risk bugs and problems trying to do things within one release when you can just let it chill for a year and maybe not do any work at all ?

Don't let me stop anyone actually doing the work but it seems to be impatience before sanity ?

Alan

Alan Cox

2011-04-04 10:05 UTC #136 lore raw

Re: [PATCH 16/18] 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle()

In reply to Trinabh Gupta

Quoted 4 lines

There are other problems too. This design of pm_idle has been copied by numerous other architectures. arm/blackfin/cris/ia64/m32r/m68knomm /microblaze/mn10300/sh/sparc all have pm_idle. This will keep spreading in future I guess.

Presumably because they've decided it is a good model and works for them. That's a matter for their arch maintainers surely.

Quoted 5 lines

https://lkml.org/lkml/2010/10/19/449 . The problem is that it results in two places of registration: cpuidle subsystem and this. It was pointed that 99.99% of people run cpuidle and we should directly call cpuidle and use its registration mechanism rather than duplicate code.

That makes sense. However what Len is trying to do doesn't seem to.

The less likely case is that at some point within the year it turns out a few people do need and care about it, so it needs shuffling into cpuidle nicely.

Don't let me stop anyone actually doing the work but it seems to be impatience before sanity ?

Alan

Alan Cox

2011-04-02 21:00 UTC #137 lore raw

Re: [PATCH 16/18] 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle()

In reply to Len Brown

Quoted 7 lines

This patch series was posted in reply to a table of contents
https://lkml.org/lkml/2011/4/2/8
"By the end of this series, pm_idle is removed as a public
x86 idle-loop registration mechanism. A few other things are cleaned up in the process."

Quoted 2 lines

Trinabh also replied to you, pointing one of the previous LKML discussions about the mis-use of pm_idle.

And there are misuses of just about every kernel symbol - kmalloc for example causes some people a lot of trouble !

Quoted 5 lines

We'll create a new APM cpuidle driver in Linux (Trinabh prototyped one), and at the same time, schedule it for removal in a year. Personally, I think it is make-work, and in real-life it is more likely to do more harm than removing apm_idle, but I don't want to stand in the way of process.

So you could just leave it alone - that's less work, less disruption and doesn't do any harm at all.

As I read this the plan at the moment otherwise is

- churn up all the code
- remove PM idle hook
- rewrite the APM code
- replace the APM code

whereas you could just leave the symbol exported or even just a hook to make people to do it right using:

	int register_pm_idle(function);

Simples yes ?

and then wait a year

For that matter instead of writing a new driver you could just stuff APM into same hooks we have for virtualisation !

This whole patch series appears to be a giant piece of pointless makework.

Alan

Alan Cox

2011-04-02 11:40 UTC #138 lore raw

Re: [PATCH 16/18] 2.6.40: x86 idle APM: remove deprecated apm_cpu_idle()

In reply to Len Brown

Quoted 5 lines · On Sat, 02 Apr 2011 02:22:58 -0400 Len Brown <[email protected]> wrote:

From: Len Brown <[email protected]>
There is some doubt whether the APM idle feature to call into the BIOS from the idle loop is reliable. Certainly it was known to fail on some machines,

And it was known to work on lots - a point that despite repeated reminding you seem keen to ignore.

The fundamental problem I have with this patch set is this

You've provided no architectural overall justification for all this effort. What is the big picture around your crusade here ? What is the grand plan ?

Quoted 3 lines

but more importantly, APM machines have not shipped for a decade and so finding machines to test the code is problematic.

So don't test it - if it's wrong someone will let you know, believe me 8)

And 2.6.40 is far too soon - it takes about a year for stuff to rattle through to leading edge distro users in bulk

Alan

Len Brown

author reviewer

2011-04-02 06:22 UTC #139 lore raw

PATCH 17/18 2.6.40: x86 idle: do not export default_idle() and (pm_idle)()

In reply to Len Brown

From: Len Brown <[email protected]>

With the removal of apm_cpu_idle(), we can now remove EXPORT_SYMBOL() for both default_idle() and (pm_idle)().

Further, make default_idle() static.
(pm_idle)() is still global b/c it is used by cpu_idle().

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/system.h |    2 --
 arch/x86/kernel/process.c     |    8 +-------
 2 files changed, 1 insertions(+), 9 deletions(-)

arch/x86/include/asm/system.h +0 -2

index 013dd42..a3379bc 100644
@@ -338,8 +338,6 @@ void cpu_idle_wait(void);
 extern unsigned long arch_align_stack(unsigned long sp);
 extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
 
-void default_idle(void);
-
 void stop_this_cpu(void *dummy);
 
 /*

arch/x86/kernel/process.c +1 -7

index 53fb569..8daa323 100644
@@ -340,15 +340,12 @@ EXPORT_SYMBOL(boot_option_idle_override);
  * Powermanagement idle function, if any..
  */
 void (*pm_idle)(void);
-#if defined(CONFIG_APM_MODULE) && defined(CONFIG_APM_CPU_IDLE)
-EXPORT_SYMBOL(pm_idle);
-#endif
 
 /*
  * We use this if we don't have any better
  * idle routine..
  */
-void default_idle(void)
+static void default_idle(void)
 {
 	trace_power_start(POWER_CSTATE, 1, smp_processor_id());
 	trace_cpu_idle(1, smp_processor_id());

@@ -367,9 +364,6 @@ void default_idle(void)
 	trace_power_end(smp_processor_id());
 	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
 }
-#if defined(CONFIG_APM_MODULE) && defined(CONFIG_APM_CPU_IDLE)
-EXPORT_SYMBOL(default_idle);
-#endif
 
 void stop_this_cpu(void *dummy)
 {

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 07:02 UTC #140 lore raw

PATCH 17/18 2.6.40: x86 idle: do not export default_idle() and (pm_idle)()

In reply to Len Brown

From: Len Brown <[email protected]>

With the removal of apm_cpu_idle(), we can now remove EXPORT_SYMBOL() for both default_idle() and (pm_idle)().

Further, make default_idle() static.
(pm_idle)() is still global b/c it is used by cpu_idle().

cc [email protected]

Signed-off-by Len Brown <[email protected]>

---
 arch/x86/include/asm/system.h |    2 --
 arch/x86/kernel/process.c     |    8 +-------
 2 files changed, 1 insertions(+), 9 deletions(-)

arch/x86/include/asm/system.h +0 -2

index 013dd42..a3379bc 100644
@@ -338,8 +338,6 @@ void cpu_idle_wait(void);
 extern unsigned long arch_align_stack(unsigned long sp);
 extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
 
-void default_idle(void);
-
 void stop_this_cpu(void *dummy);
 
 /*

arch/x86/kernel/process.c +1 -7

index 53fb569..8daa323 100644
@@ -340,15 +340,12 @@ EXPORT_SYMBOL(boot_option_idle_override);
  * Powermanagement idle function, if any..
  */
 void (*pm_idle)(void);
-#if defined(CONFIG_APM_MODULE) && defined(CONFIG_APM_CPU_IDLE)
-EXPORT_SYMBOL(pm_idle);
-#endif
 
 /*
  * We use this if we don't have any better
  * idle routine..
  */
-void default_idle(void)
+static void default_idle(void)
 {
 	trace_power_start(POWER_CSTATE, 1, smp_processor_id());
 	trace_cpu_idle(1, smp_processor_id());

@@ -367,9 +364,6 @@ void default_idle(void)
 	trace_power_end(smp_processor_id());
 	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
 }
-#if defined(CONFIG_APM_MODULE) && defined(CONFIG_APM_CPU_IDLE)
-EXPORT_SYMBOL(default_idle);
-#endif
 
 void stop_this_cpu(void *dummy)
 {

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 06:23 UTC #141 lore raw

PATCH 18/18 2.6.40: x86 idle: remove deprecated mwait_idle()

In reply to Len Brown

From: Len Brown <[email protected]>

For ACPI mode, mwait_with_hints() in cstate.c is used instead of mwait_idle().

For INTEL_IDLE mode, the mwait in intel_idle() is used instead of mwait_idle().

So mwait_idle() is used only on hardware that supports MWAIT, but is running a !ACPI && !INTEL_IDLE kernel.
Such a system will run HLT instead of MWAIT after this change.

cc [email protected]

Acked-by Andreas Herrmann <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |    7 -----
 Documentation/kernel-parameters.txt        |    7 +----
 arch/x86/include/asm/processor.h           |    2 +-
 arch/x86/kernel/process.c                  |   35 +---------------------------
 drivers/acpi/processor_idle.c              |    1 -
 5 files changed, 3 insertions(+), 49 deletions(-)

Documentation/feature-removal-schedule.txt +0 -7

index 9b84b1a..f55ba2c 100644
@@ -6,13 +6,6 @@ be removed from this file.
 
 ----------------------------
 
-What:	x86 "idle=mwait" cmdline param
-When:	2.6.40
-Why:	simplify x86 idle code
-Who:	Len Brown <[email protected]>
-
-----------------------------
-
 What:	PRISM54
 When:	2.6.34

Documentation/kernel-parameters.txt +1 -6

index a9db94e..52c956a 100644
@@ -920,16 +920,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			Claim all unknown PCI IDE storage controllers.
 
 	idle=		[X86]
-			Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
+			Format: idle=poll, idle=halt, idle=nomwait
 			Poll forces a polling idle loop that can slightly
 			improve the performance of waking up a idle CPU, but
 			will use a lot of power and make the system run hot.
 			Not recommended.
-			idle=mwait: On systems which support MONITOR/MWAIT but
-			the kernel chose to not use it because it doesn't save
-			as much power as a normal idle loop, use the
-			MONITOR/MWAIT idle loop anyways. Performance should be
-			the same as idle=poll.
 			idle=halt: Halt is forced to be used for CPU idle.
 			In such case C2/C3 won't be used again.
 			idle=nomwait: Disable mwait for CPU C-states

arch/x86/include/asm/processor.h +1 -1

index 10cdee8..3424009 100644
@@ -752,7 +752,7 @@ extern unsigned long		boot_option_idle_override;
 extern bool			amd_e400_detected;
 
 enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
-			 IDLE_POLL, IDLE_FORCE_MWAIT};
+			 IDLE_POLL};
 
 extern void enable_sep_cpu(void);
 extern int sysenter_setup(void);

arch/x86/kernel/process.c +1 ~~-34~~

index 8daa323..4ab4bba 100644
@@ -399,27 +399,6 @@ void cpu_idle_wait(void)
 }
 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 
-/* Default MONITOR/MWAIT with no hints, used for default C1 state */
-static void mwait_idle(void)
-{
-	if (!need_resched()) {
-		trace_power_start(POWER_CSTATE, 1, smp_processor_id());
-		trace_cpu_idle(1, smp_processor_id());
-		if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
-			clflush((void *)&current_thread_info()->flags);
-
-		__monitor((void *)&current_thread_info()->flags, 0, 0);
-		smp_mb();
-		if (!need_resched())
-			__sti_mwait(0, 0);
-		else
-			local_irq_enable();
-		trace_power_end(smp_processor_id());
-		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
-	} else
-		local_irq_enable();
-}
-
 /*
  * On SMP it's slightly faster (but much more power-consuming!)
  * to poll the ->work.need_resched flag instead of waiting for the

@@ -457,9 +436,6 @@ int mwait_usable(const struct cpuinfo_x86 *c)
 {
 	u32 eax, ebx, ecx, edx;
 
-	if (boot_option_idle_override == IDLE_FORCE_MWAIT)
-		return 1;
-
 	if (c->cpuid_level < MWAIT_INFO)
 		return 0;

@@ -548,13 +524,7 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 	if (pm_idle)
 		return;
 
-	if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
-		/*
-		 * One CPU supports mwait => All CPUs supports mwait
-		 */
-		printk(KERN_INFO "using mwait in idle threads.\n");
-		pm_idle = mwait_idle;
-	} else if (cpu_has_amd_erratum(amd_erratum_400)) {
+	if (cpu_has_amd_erratum(amd_erratum_400)) {
 		/* E400: APIC timer interrupt does not wake up CPU from C1e */
 		printk(KERN_INFO "using E400 aware idle routine\n");
 		pm_idle = amd_e400_idle;

@@ -578,9 +548,6 @@ static int __init idle_setup(char *str)
 		printk("using polling idle threads.\n");
 		pm_idle = poll_idle;
 		boot_option_idle_override = IDLE_POLL;
-	} else if (!strcmp(str, "mwait")) {
-		boot_option_idle_override = IDLE_FORCE_MWAIT;
-		WARN_ONCE(1, "\idle=mwait\" will be removed in 2.6.40\"\n");
 	} else if (!strcmp(str, "halt")) {
 		/*
 		 * When the boot option of idle=halt is added, halt is

drivers/acpi/processor_idle.c +0 -1

index 53d9f10..954a9d3 100644
@@ -82,7 +82,6 @@ module_param(latency_factor, uint, 0644);
 static int disabled_by_idle_boot_param(void)
 {
 	return boot_option_idle_override == IDLE_POLL ||
-		boot_option_idle_override == IDLE_FORCE_MWAIT ||
 		boot_option_idle_override == IDLE_HALT;
 }

Signature · 1 line

1.7.5.rc0

Len Brown

author reviewer

2011-04-02 07:02 UTC #142 lore raw

PATCH 18/18 2.6.40: x86 idle: remove deprecated mwait_idle()

In reply to Len Brown

From: Len Brown <[email protected]>

For ACPI mode, mwait_with_hints() in cstate.c is used instead of mwait_idle().

For INTEL_IDLE mode, the mwait in intel_idle() is used instead of mwait_idle().

So mwait_idle() is used only on hardware that supports MWAIT, but is running a !ACPI && !INTEL_IDLE kernel.
Such a system will run HLT instead of MWAIT after this change.

cc [email protected]

Acked-by Andreas Herrmann <[email protected]>

Signed-off-by Len Brown <[email protected]>

---
 Documentation/feature-removal-schedule.txt |    7 -----
 Documentation/kernel-parameters.txt        |    7 +----
 arch/x86/include/asm/processor.h           |    2 +-
 arch/x86/kernel/process.c                  |   35 +---------------------------
 drivers/acpi/processor_idle.c              |    1 -
 5 files changed, 3 insertions(+), 49 deletions(-)

Documentation/feature-removal-schedule.txt +0 -7

index 9b84b1a..f55ba2c 100644
@@ -6,13 +6,6 @@ be removed from this file.
 
 ----------------------------
 
-What:	x86 "idle=mwait" cmdline param
-When:	2.6.40
-Why:	simplify x86 idle code
-Who:	Len Brown <[email protected]>
-
-----------------------------
-
 What:	PRISM54
 When:	2.6.34

Documentation/kernel-parameters.txt +1 -6

index a9db94e..52c956a 100644
@@ -920,16 +920,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			Claim all unknown PCI IDE storage controllers.
 
 	idle=		[X86]
-			Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
+			Format: idle=poll, idle=halt, idle=nomwait
 			Poll forces a polling idle loop that can slightly
 			improve the performance of waking up a idle CPU, but
 			will use a lot of power and make the system run hot.
 			Not recommended.
-			idle=mwait: On systems which support MONITOR/MWAIT but
-			the kernel chose to not use it because it doesn't save
-			as much power as a normal idle loop, use the
-			MONITOR/MWAIT idle loop anyways. Performance should be
-			the same as idle=poll.
 			idle=halt: Halt is forced to be used for CPU idle.
 			In such case C2/C3 won't be used again.
 			idle=nomwait: Disable mwait for CPU C-states

arch/x86/include/asm/processor.h +1 -1

index 10cdee8..3424009 100644
@@ -752,7 +752,7 @@ extern unsigned long		boot_option_idle_override;
 extern bool			amd_e400_detected;
 
 enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_NOMWAIT,
-			 IDLE_POLL, IDLE_FORCE_MWAIT};
+			 IDLE_POLL};
 
 extern void enable_sep_cpu(void);
 extern int sysenter_setup(void);

arch/x86/kernel/process.c +1 ~~-34~~

index 8daa323..4ab4bba 100644
@@ -399,27 +399,6 @@ void cpu_idle_wait(void)
 }
 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 
-/* Default MONITOR/MWAIT with no hints, used for default C1 state */
-static void mwait_idle(void)
-{
-	if (!need_resched()) {
-		trace_power_start(POWER_CSTATE, 1, smp_processor_id());
-		trace_cpu_idle(1, smp_processor_id());
-		if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
-			clflush((void *)&current_thread_info()->flags);
-
-		__monitor((void *)&current_thread_info()->flags, 0, 0);
-		smp_mb();
-		if (!need_resched())
-			__sti_mwait(0, 0);
-		else
-			local_irq_enable();
-		trace_power_end(smp_processor_id());
-		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
-	} else
-		local_irq_enable();
-}
-
 /*
  * On SMP it's slightly faster (but much more power-consuming!)
  * to poll the ->work.need_resched flag instead of waiting for the

@@ -457,9 +436,6 @@ int mwait_usable(const struct cpuinfo_x86 *c)
 {
 	u32 eax, ebx, ecx, edx;
 
-	if (boot_option_idle_override == IDLE_FORCE_MWAIT)
-		return 1;
-
 	if (c->cpuid_level < MWAIT_INFO)
 		return 0;

@@ -548,13 +524,7 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 	if (pm_idle)
 		return;
 
-	if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
-		/*
-		 * One CPU supports mwait => All CPUs supports mwait
-		 */
-		printk(KERN_INFO "using mwait in idle threads.\n");
-		pm_idle = mwait_idle;
-	} else if (cpu_has_amd_erratum(amd_erratum_400)) {
+	if (cpu_has_amd_erratum(amd_erratum_400)) {
 		/* E400: APIC timer interrupt does not wake up CPU from C1e */
 		printk(KERN_INFO "using E400 aware idle routine\n");
 		pm_idle = amd_e400_idle;

@@ -578,9 +548,6 @@ static int __init idle_setup(char *str)
 		printk("using polling idle threads.\n");
 		pm_idle = poll_idle;
 		boot_option_idle_override = IDLE_POLL;
-	} else if (!strcmp(str, "mwait")) {
-		boot_option_idle_override = IDLE_FORCE_MWAIT;
-		WARN_ONCE(1, "\idle=mwait\" will be removed in 2.6.40\"\n");
 	} else if (!strcmp(str, "halt")) {
 		/*
 		 * When the boot option of idle=halt is added, halt is

drivers/acpi/processor_idle.c +0 -1

index 53d9f10..954a9d3 100644
@@ -82,7 +82,6 @@ module_param(latency_factor, uint, 0644);
 static int disabled_by_idle_boot_param(void)
 {
 	return boot_option_idle_override == IDLE_POLL ||
-		boot_option_idle_override == IDLE_FORCE_MWAIT ||
 		boot_option_idle_override == IDLE_HALT;
 }

Signature · 1 line

1.7.5.rc0