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[PATCH] [0/7] Add noclflush option and related cleanup

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[view original message]
From: Andi Kleen <ak@...>
To: <mingo@...>, <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: [PATCH] [0/7] Add noclflush option and related cleanup
Date: Friday, January 18, 2008 - 1:27 pm

I added a noclflush option because Ingo asked for it to make

it possible to disable parts of the new CPA code.


While I was at it I did some generic cleanup in the area of cpuid disable

options and generalized them a bit. That is where the other patches come from.


-Andi

--
[view original message]
From: Andi Kleen <ak@...>
To: <mingo@...>, <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: [PATCH] [7/7] Add generic clearcpuid=... option
Date: Friday, January 18, 2008 - 1:27 pm

Add a generic option to clear any cpuid bit. I added it because it was

very easy to add with the new generic cpuid disable bitmap and perhaps

it will be useful in the future.


Signed-off-by: Andi Kleen <ak@suse.de>


---

 Documentation/kernel-parameters.txt |   13 +++++++++++++

 arch/x86/kernel/cpu/common.c        |   11 +++++++++++

 arch/x86/kernel/setup_64.c          |   11 +++++++++++

 3 files changed, 35 insertions(+)


Index: linux/arch/x86/kernel/cpu/common.c

===================================================================

--- linux.orig/arch/x86/kernel/cpu/common.c

+++ linux/arch/x86/kernel/cpu/common.c

@@ -572,6 +572,17 @@ void __cpuinit print_cpu_info(struct cpu

 		printk("\n");

 }


+static __init int setup_disablecpuid(char *arg)

+{

+	int bit;

+	if (get_option(&arg, &bit) && bit < NCAPINTS*32)

+		setup_clear_cpu_cap(bit);

+	else

+		return 0;

+	return 1;

+}

+__setup("clearcpuid=", setup_disablecpuid);

+

 cpumask_t cpu_initialized __cpuinitdata = CPU_MASK_NONE;


 /* This is hacky. :)

Index: linux/arch/x86/kernel/setup_64.c

===================================================================

--- linux.orig/arch/x86/kernel/setup_64.c

+++ linux/arch/x86/kernel/setup_64.c

@@ -1060,6 +1060,17 @@ void __cpuinit print_cpu_info(struct cpu

 		printk(KERN_CONT "\n");

 }


+static __init int setup_disablecpuid(char *arg)

+{

+	int bit;

+	if (get_option(&arg, &bit) && bit < NCAPINTS*32)

+		setup_clear_cpu_cap(bit);

+	else

+		return 0;

+	return 1;

+}

+__setup("clearcpuid=", setup_disablecpuid);

+

 /*

  *	Get CPU information for use by the procfs.

  */

Index: linux/Documentation/kernel-parameters.txt

===================================================================

--- linux.orig/Documentation/kernel-parameters.txt

+++ linux/Documentation/kernel-parameters.txt

@@ -408,6 +408,19 @@ and is between 256 and 4096 characters.

 			[SPARC64] tick

 			[X86-64] hpet,tsc


+	clearcpuid=BITNUM [X86]

+			Disable CPUID ...
[ message continues ]
[view original message]
From: Andi Kleen <ak@...>
To: <mingo@...>, <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: [PATCH] [6/7] Add noclflush option
Date: Friday, January 18, 2008 - 1:27 pm

To disable CLFLUSH usage, especially in change_page_attr().


Ingo asked for this.


Signed-off-by: Andi Kleen <ak@suse.de>


---

 Documentation/kernel-parameters.txt |    2 ++

 arch/x86/kernel/cpu/common.c        |    7 +++++++

 arch/x86/kernel/setup_64.c          |    7 +++++++

 3 files changed, 16 insertions(+)


Index: linux/arch/x86/kernel/cpu/common.c

===================================================================

--- linux.orig/arch/x86/kernel/cpu/common.c

+++ linux/arch/x86/kernel/cpu/common.c

@@ -542,6 +542,13 @@ void __cpuinit detect_ht(struct cpuinfo_

 }

 #endif


+static __init int setup_noclflush(char *arg)

+{

+	setup_clear_cpu_cap(X86_FEATURE_CLFLSH);

+	return 1;

+}

+__setup("noclflush", setup_noclflush);

+

 void __cpuinit print_cpu_info(struct cpuinfo_x86 *c)

 {

 	char *vendor = NULL;

Index: linux/arch/x86/kernel/setup_64.c

===================================================================

--- linux.orig/arch/x86/kernel/setup_64.c

+++ linux/arch/x86/kernel/setup_64.c

@@ -1042,6 +1042,13 @@ void __cpuinit identify_cpu(struct cpuin

 	}

 }


+static __init int setup_noclflush(char *arg)

+{

+	setup_clear_cpu_cap(X86_FEATURE_CLFLSH);

+	return 1;

+}

+__setup("noclflush", setup_noclflush);

+

 void __cpuinit print_cpu_info(struct cpuinfo_x86 *c)

 {

 	if (c->x86_model_id[0])

Index: linux/Documentation/kernel-parameters.txt

===================================================================

--- linux.orig/Documentation/kernel-parameters.txt

+++ linux/Documentation/kernel-parameters.txt

@@ -1173,6 +1173,8 @@ and is between 256 and 4096 characters.

 			register save and restore. The kernel will only save

 			legacy floating-point registers on task switch.


+	noclflush	[BUGS=X86] Don't use the CLFLUSH instruction

+

 	nohlt		[BUGS=ARM]


 	no-hlt		[BUGS=X86-32] Tells the kernel that the hlt

--
[view original message]
From: Andi Kleen <ak@...>
To: <mingo@...>, <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: [PATCH] [5/7] Remove CONFIG_X86_TSC for 32bit
Date: Friday, January 18, 2008 - 1:27 pm

The config option protects so little code that it is fairly pointless.

Also a lot of its code was related to itself only (as in panicing without

TSC). And TSC less CPUs are completely handled at runtime anyways.


This makes 32bit behaviour match x86-64.


I also removed an #if defined(CONFIG_X86_GENERIC) in get_cycles. Not sure

what that was good for, it didn't make any sense.


Signed-off-by: Andi Kleen <ak@suse.de>


---

 arch/x86/Kconfig.cpu          |    4 ----

 arch/x86/kernel/cpu/bugs.c    |    8 --------

 arch/x86/kernel/tsc_32.c      |   10 ----------

 drivers/acpi/processor_idle.c |   10 +++++-----

 include/asm-x86/tsc.h         |    6 ------

 5 files changed, 5 insertions(+), 33 deletions(-)


Index: linux/arch/x86/kernel/cpu/bugs.c

===================================================================

--- linux.orig/arch/x86/kernel/cpu/bugs.c

+++ linux/arch/x86/kernel/cpu/bugs.c

@@ -151,14 +151,6 @@ static void __init check_config(void)

 #endif


 /*

- * If we configured ourselves for a TSC, we'd better have one!

- */

-#ifdef CONFIG_X86_TSC

-	if (!cpu_has_tsc)

-		panic("Kernel compiled for Pentium+, requires TSC feature!");

-#endif

-

-/*

  * If we were told we had a good local APIC, check for buggy Pentia,

  * i.e. all B steppings and the C2 stepping of P54C when using their

  * integrated APIC (see 11AP erratum in "Pentium Processor

Index: linux/arch/x86/kernel/tsc_32.c

===================================================================

--- linux.orig/arch/x86/kernel/tsc_32.c

+++ linux/arch/x86/kernel/tsc_32.c

@@ -24,14 +24,6 @@ static int tsc_enabled;

 unsigned int tsc_khz;

 EXPORT_SYMBOL_GPL(tsc_khz);


-#ifdef CONFIG_X86_TSC

-static int __init tsc_setup(char *str)

-{

-	printk(KERN_WARNING "notsc: Kernel compiled with CONFIG_X86_TSC, "

-				"cannot disable TSC.\n");

-	return 1;

-}

-#else

 /*

  * disable flag for tsc. Takes effect by clearing the TSC cpu flag

  * in cpu/common.c

@@ -41,8 +33,6 @@ static int __init tsc_setup(char *str)

 	setup...
[ message continues ]
[view original message]
From: Andi Kleen <andi@...>
To: <mingo@...>
Cc: <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: Re: [PATCH] [5/7] Remove CONFIG_X86_TSC for 32bit II
Date: Friday, January 18, 2008 - 5:05 pm

Hmm, during further testing i found that the patch causes boot failures

in some configuration. I withdraw this one for now.


The other patches in the series are independent and should be still

considered for merging.


-Andi

--
[view original message]
From: Ingo Molnar <mingo@...>
To: Andi Kleen <andi@...>
Cc: <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: Re: [PATCH] [5/7] Remove CONFIG_X86_TSC for 32bit II
Date: Friday, January 18, 2008 - 6:06 pm

ok, pulled. In what situations did it fail? It worked fine on a (small) 


yep, they are in and have caused no problems so far.


	Ingo

--
[view original message]
From: Andi Kleen <ak@...>
To: <mingo@...>, <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: [PATCH] [4/7] Convert TSC disabling to generic cpuid disable bitmap
Date: Friday, January 18, 2008 - 1:27 pm

This cleans up quite a lot of code.


I think I test compiled all the affected variants (voyager, numaq),

but didn't test them, but the change is pretty straight forward for

them. 


This means NUMAQ didn't compile, but I don't think it was related

to my patches.


Signed-off-by: Andi Kleen <ak@suse.de>


---

 arch/x86/kernel/cpu/bugs.c    |    2 +-

 arch/x86/kernel/cpu/common.c  |    9 ---------

 arch/x86/kernel/numaq_32.c    |    2 +-

 arch/x86/kernel/tsc_32.c      |   14 +++-----------

 arch/x86/mach-voyager/setup.c |    2 +-

 arch/x86/xen/time.c           |    2 +-

 include/asm-x86/tsc.h         |    2 --

 7 files changed, 7 insertions(+), 26 deletions(-)


Index: linux/arch/x86/kernel/cpu/bugs.c

===================================================================

--- linux.orig/arch/x86/kernel/cpu/bugs.c

+++ linux/arch/x86/kernel/cpu/bugs.c

@@ -154,7 +154,7 @@ static void __init check_config(void)

  * If we configured ourselves for a TSC, we'd better have one!

  */

 #ifdef CONFIG_X86_TSC

-	if (!cpu_has_tsc && !tsc_disable)

+	if (!cpu_has_tsc)

 		panic("Kernel compiled for Pentium+, requires TSC feature!");

 #endif


Index: linux/arch/x86/kernel/cpu/common.c

===================================================================

--- linux.orig/arch/x86/kernel/cpu/common.c

+++ linux/arch/x86/kernel/cpu/common.c

@@ -446,10 +446,6 @@ void __cpuinit identify_cpu(struct cpuin

 	 * we do "generic changes."

 	 */


-	/* TSC disabled? */

-	if ( tsc_disable )

-		clear_bit(X86_FEATURE_TSC, c->x86_capability);

-

 	/* If the model name is still unset, do table lookup. */

 	if ( !c->x86_model_id[0] ) {

 		char *p;

@@ -650,11 +646,6 @@ void __cpuinit cpu_init(void)


 	if (cpu_has_vme || cpu_has_tsc || cpu_has_de)

 		clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE);

-	if (tsc_disable && cpu_has_tsc) {

-		printk(KERN_NOTICE "Disabling TSC...\n");

-		/**** FIX-HPA: DOES THIS REALLY BELONG HERE? ****/

-		clear_bit(X86_FEATURE_TSC, boot_c...
[ message continues ]
[view original message]
From: Ian Campbell <ijc@...>
To: Andi Kleen <ak@...>
Cc: <mingo@...>, <hpa@...>, <tglx@...>, <linux-kernel@...>, Jeremy Fitzhardinge <jeremy@...>
Subject: Re: [PATCH] [4/7] Convert TSC disabling to generic cpuid disable bitmap
Date: Saturday, January 19, 2008 - 2:18 pm

Should have added Jeremy to CC, sorry for the duplicate message.


That inverts the meaning, doesn't it? Previously the code force the TSC

to be on and now it forcefully disables it. Now when booting a Xen guest

I get:

        Kernel panic - not syncing: Kernel compiled for Pentium+, requires TSC feature!


I think you want something like the following

From: Ian Campbell <ijc@hellion.org.uk>

Date: Sat, 19 Jan 2008 18:08:23 +0000

Subject: [PATCH] x86: Xen requires TSC support to be forced on, not disabled.


Signed-off-by: Ian Campbell <ijc@hellion.org.uk>

---

 arch/x86/xen/time.c          |    2 +-

 include/asm-x86/cpufeature.h |    4 ++++

 2 files changed, 5 insertions(+), 1 deletions(-)


diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c

index 6f5c74a..b3721fd 100644

--- a/arch/x86/xen/time.c

+++ b/arch/x86/xen/time.c

@@ -592,7 +592,7 @@ __init void xen_time_init(void)

 	set_normalized_timespec(&wall_to_monotonic,

 				-xtime.tv_sec, -xtime.tv_nsec);


-	setup_clear_cpu_cap(X86_FEATURE_TSC);

+	setup_force_cpu_cap(X86_FEATURE_TSC);


 	xen_setup_timer(cpu);

 	xen_setup_cpu_clockevents();

diff --git a/include/asm-x86/cpufeature.h b/include/asm-x86/cpufeature.h

index 91a7665..b6f969c 100644

--- a/include/asm-x86/cpufeature.h

+++ b/include/asm-x86/cpufeature.h

@@ -135,6 +135,10 @@

 	clear_cpu_cap(&boot_cpu_data, bit);	\

 	set_bit(bit, cleared_cpu_caps); 	\

 } while (0)

+#define setup_force_cpu_cap(bit) do { \

+	set_cpu_cap(&boot_cpu_data, bit);	\

+	clear_bit(bit, cleared_cpu_caps); 	\

+} while (0)


 #define cpu_has_fpu		boot_cpu_has(X86_FEATURE_FPU)

 #define cpu_has_vme		boot_cpu_has(X86_FEATURE_VME)

--

1.5.3.8


--

Ian Campbell


All that glitters is not gold; all that wander are not lost.


--
[view original message]
From: Ian Campbell <ijc@...>
To: Andi Kleen <ak@...>
Cc: <mingo@...>, <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: Re: [PATCH] [4/7] Convert TSC disabling to generic cpuid disable bitmap
Date: Saturday, January 19, 2008 - 2:15 pm

That inverts the meaning, doesn't it? Previously the code force the TSC

to be on and now it forcefully disables it. Now when booting a Xen guest

I get:

        Kernel panic - not syncing: Kernel compiled for Pentium+, requires TSC feature!


I think you want something like the following

From: Ian Campbell <ijc@hellion.org.uk>

Date: Sat, 19 Jan 2008 18:08:23 +0000

Subject: [PATCH] x86: Xen requires TSC support to be forced on, not disabled.


Signed-off-by: Ian Campbell <ijc@hellion.org.uk>

---

 arch/x86/xen/time.c          |    2 +-

 include/asm-x86/cpufeature.h |    4 ++++

 2 files changed, 5 insertions(+), 1 deletions(-)


diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c

index 6f5c74a..b3721fd 100644

--- a/arch/x86/xen/time.c

+++ b/arch/x86/xen/time.c

@@ -592,7 +592,7 @@ __init void xen_time_init(void)

 	set_normalized_timespec(&wall_to_monotonic,

 				-xtime.tv_sec, -xtime.tv_nsec);


-	setup_clear_cpu_cap(X86_FEATURE_TSC);

+	setup_force_cpu_cap(X86_FEATURE_TSC);


 	xen_setup_timer(cpu);

 	xen_setup_cpu_clockevents();

diff --git a/include/asm-x86/cpufeature.h b/include/asm-x86/cpufeature.h

index 91a7665..b6f969c 100644

--- a/include/asm-x86/cpufeature.h

+++ b/include/asm-x86/cpufeature.h

@@ -135,6 +135,10 @@

 	clear_cpu_cap(&boot_cpu_data, bit);	\

 	set_bit(bit, cleared_cpu_caps); 	\

 } while (0)

+#define setup_force_cpu_cap(bit) do { \

+	set_cpu_cap(&boot_cpu_data, bit);	\

+	clear_bit(bit, cleared_cpu_caps); 	\

+} while (0)


 #define cpu_has_fpu		boot_cpu_has(X86_FEATURE_FPU)

 #define cpu_has_vme		boot_cpu_has(X86_FEATURE_VME)

--

1.5.3.8


--

Ian Campbell


All that glitters is not gold; all that wander are not lost.


--
[view original message]
From: Andi Kleen <ak@...>
To: Ian Campbell <ijc@...>
Cc: <mingo@...>, <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: Re: [PATCH] [4/7] Convert TSC disabling to generic cpuid disable bitmap
Date: Saturday, January 19, 2008 - 2:57 pm

You're right -- i was a bit overzealous in search'n'replace with that one.


Actually that would be only needed if someone else disabled TSC explicitely before.


Simply deleting this should be sufficient. Does this patch work for you?


It would break if someone passes notsc to a Xen kernel, but then a lot of options make the kernel

break if you don't know what you're doing so that doesn't seem like a big issue.


-Andi


---


Don't disable TSC in Xen boot


That was a typo in the previous TSC option changes.


TSC shouldn't be disabled at this point, so just don't do anything.


Signed-off-by: Andi Kleen <ak@suse.de>


Index: linux/arch/x86/xen/time.c

===================================================================

--- linux.orig/arch/x86/xen/time.c

+++ linux/arch/x86/xen/time.c

@@ -592,8 +592,6 @@ __init void xen_time_init(void)

 	set_normalized_timespec(&wall_to_monotonic,

 				-xtime.tv_sec, -xtime.tv_nsec);


-	setup_clear_cpu_cap(X86_FEATURE_TSC);

-

 	xen_setup_timer(cpu);

 	xen_setup_cpu_clockevents();

 }

--
[view original message]
From: Ian Campbell <ijc@...>
To: Andi Kleen <ak@...>
Cc: <mingo@...>, <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: Re: [PATCH] [4/7] Convert TSC disabling to generic cpuid disable bitmap
Date: Saturday, January 19, 2008 - 6:29 pm

I'm happy either way. I think the Xen paravirt subsystem will use TSC

where it has to due to the Xen architecture regardless of this setting.


Ian.

--

Ian Campbell


Good day for overcoming obstacles.  Try a steeplechase.


--
[view original message]
From: Andi Kleen <ak@...>
To: <mingo@...>, <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: [PATCH] [3/7] Don't disable RDTSC in userland for 32bit notsc
Date: Friday, January 18, 2008 - 1:27 pm

Modern 32bit userland doesn't even boot when the TSC is disabled

because ld.so tends to contain RDTSCs.  So make notsc only effective for the

kernel, similar to 64bit.

Signed-off-by: Andi Kleen <ak@suse.de>


---

 arch/x86/kernel/cpu/common.c |    1 -

 1 file changed, 1 deletion(-)


Index: linux/arch/x86/kernel/cpu/common.c

===================================================================

--- linux.orig/arch/x86/kernel/cpu/common.c

+++ linux/arch/x86/kernel/cpu/common.c

@@ -654,7 +654,6 @@ void __cpuinit cpu_init(void)

 		printk(KERN_NOTICE "Disabling TSC...\n");

 		/**** FIX-HPA: DOES THIS REALLY BELONG HERE? ****/

 		clear_bit(X86_FEATURE_TSC, boot_cpu_data.x86_capability);

-		set_in_cr4(X86_CR4_TSD);

 	}


 	load_idt(&idt_descr);

--
[view original message]
From: Andi Kleen <ak@...>
To: <mingo@...>, <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: [PATCH] [2/7] Convert some existing cpuid disable options to new generic bitmap
Date: Friday, January 18, 2008 - 1:27 pm

This convers nofxsr, mem=nopentium and nosep to use the new

generic cpuid disable bitmap instead of using own variables.


Signed-off-by: Andi Kleen <ak@suse.de>


---

 arch/x86/kernel/cpu/common.c |   34 ++++------------------------------

 arch/x86/kernel/setup_32.c   |    5 +----

 2 files changed, 5 insertions(+), 34 deletions(-)


Index: linux/arch/x86/kernel/cpu/common.c

===================================================================

--- linux.orig/arch/x86/kernel/cpu/common.c

+++ linux/arch/x86/kernel/cpu/common.c

@@ -60,14 +60,10 @@ EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);

 __u32 cleared_cpu_caps[NCAPINTS] __cpuinitdata;


 static int cachesize_override __cpuinitdata = -1;

-static int disable_x86_fxsr __cpuinitdata;

 static int disable_x86_serial_nr __cpuinitdata = 1;

-static int disable_x86_sep __cpuinitdata;


 struct cpu_dev * cpu_devs[X86_VENDOR_NUM] = {};


-extern int disable_pse;

-

 static void __cpuinit default_init(struct cpuinfo_x86 * c)

 {

 	/* Not much we can do here... */

@@ -216,16 +212,8 @@ static void __cpuinit get_cpu_vendor(str


 static int __init x86_fxsr_setup(char * s)

 {

-	/* Tell all the other CPUs to not use it... */

-	disable_x86_fxsr = 1;

-

-	/*

-	 * ... and clear the bits early in the boot_cpu_data

-	 * so that the bootup process doesn't try to do this

-	 * either.

-	 */

-	clear_bit(X86_FEATURE_FXSR, boot_cpu_data.x86_capability);

-	clear_bit(X86_FEATURE_XMM, boot_cpu_data.x86_capability);

+	setup_clear_cpu_cap(X86_FEATURE_FXSR);

+	setup_clear_cpu_cap(X86_FEATURE_XMM);

 	return 1;

 }

 __setup("nofxsr", x86_fxsr_setup);

@@ -233,7 +221,7 @@ __setup("nofxsr", x86_fxsr_setup);


 static int __init x86_sep_setup(char * s)

 {

-	disable_x86_sep = 1;

+	setup_clear_cpu_cap(X86_FEATURE_SEP);

 	return 1;

 }

 __setup("nosep", x86_sep_setup);

@@ -462,19 +450,6 @@ void __cpuinit identify_cpu(struct cpuin

 	if ( tsc_disable )

 		clear_bit(X86_FEATURE_TSC, c->x86_capability);


-	/* FXSR disabled? */

-	if (disable_x86_fxsr) {

...
[ message continues ]
[view original message]
From: Andi Kleen <ak@...>
To: <mingo@...>, <hpa@...>, <tglx@...>, <linux-kernel@...>
Subject: [PATCH] [1/7] Add frame work to disable CPUID bits on the command line
Date: Friday, January 18, 2008 - 1:27 pm

There are already various options to disable specific cpuid bits

on the command line. They all use their own variable. Add a generic

mask to make this easier in the future.


Signed-off-by: Andi Kleen <ak@suse.de>


---

 arch/x86/kernel/cpu/common.c |    6 ++++++

 arch/x86/kernel/setup_64.c   |    6 ++++++

 include/asm-x86/cpufeature.h |    4 ++++

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

 4 files changed, 17 insertions(+)


Index: linux/arch/x86/kernel/cpu/common.c

===================================================================

--- linux.orig/arch/x86/kernel/cpu/common.c

+++ linux/arch/x86/kernel/cpu/common.c

@@ -57,6 +57,8 @@ DEFINE_PER_CPU(struct gdt_page, gdt_page

 } };

 EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);


+__u32 cleared_cpu_caps[NCAPINTS] __cpuinitdata;

+

 static int cachesize_override __cpuinitdata = -1;

 static int disable_x86_fxsr __cpuinitdata;

 static int disable_x86_serial_nr __cpuinitdata = 1;

@@ -497,6 +499,10 @@ void __cpuinit identify_cpu(struct cpuin

 			boot_cpu_data.x86_capability[i] &= c->x86_capability[i];

 	}


+	/* Clear all flags overriden by options */

+	for (i = 0; i < NCAPINTS; i++)

+		c->x86_capability[i] ^= cleared_cpu_caps[i];

+

 	/* Init Machine Check Exception if available. */

 	mcheck_init(c);


Index: linux/include/asm-x86/cpufeature.h

===================================================================

--- linux.orig/include/asm-x86/cpufeature.h

+++ linux/include/asm-x86/cpufeature.h

@@ -132,6 +132,10 @@


 #define set_cpu_cap(c, bit)	set_bit(bit, (unsigned long *)((c)->x86_capability))

 #define clear_cpu_cap(c, bit)	clear_bit(bit, (unsigned long *)((c)->x86_capability))

+#define setup_clear_cpu_cap(bit) do { \

+	clear_cpu_cap(&boot_cpu_data, bit);	\

+	set_bit(bit, cleared_cpu_caps); 	\

+} while (0)


 #define cpu_has_fpu		boot_cpu_has(X86_FEATURE_FPU)

 #define cpu_has_vme		boot_cpu_has(X86_FEATURE_VME)

Index: linux/include/asm-x86/processor.h

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