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Commit b7fb4af0 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Andi Kleen
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[PATCH] i386: Allow boot-time disable of SMP altinstructions 



Add "noreplace-smp" to disable SMP instruction replacement.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent d0175ab6

Documentation/kernel-parameters.txt

+6 −0
Original line number Diff line number Diff line
@@ -1164,6 +1164,9 @@ and is between 256 and 4096 characters. It is defined in the file 


	nomce		[IA-32] Machine Check Exception



	noreplace-smp	[IA-32,SMP] Don't replace SMP instructions

			with UP alternatives



	noresidual	[PPC] Don't use residual data on PReP machines.



	noresume	[SWSUSP] Disables resume and restores original swap
@@ -1569,6 +1572,9 @@ and is between 256 and 4096 characters. It is defined in the file 
	smart2=		[HW]

			Format: <io1>[,<io2>[,...,<io8>]]



	smp-alt-once	[IA-32,SMP] On a hotplug CPU system, only

			attempt to substitute SMP alternatives once at boot.



	snd-ad1816a=	[HW,ALSA]



	snd-ad1848=	[HW,ALSA]

arch/i386/kernel/alternative.c

+19 −4
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
#include <asm/alternative.h>

#include <asm/sections.h>



static int noreplace_smp     = 0;

static int smp_alt_once      = 0;

static int debug_alternative = 0;
@@ -13,15 +14,23 @@ static int __init bootonly(char *str) 
	smp_alt_once = 1;

	return 1;

}

__setup("smp-alt-boot", bootonly);



static int __init debug_alt(char *str)

{

	debug_alternative = 1;

	return 1;

}



__setup("smp-alt-boot", bootonly);

__setup("debug-alternative", debug_alt);



static int __init setup_noreplace_smp(char *str)

{

	noreplace_smp = 1;

	return 1;

}

__setup("noreplace-smp", setup_noreplace_smp);





#define DPRINTK(fmt, args...) if (debug_alternative) \

	printk(KERN_DEBUG fmt, args)
@@ -185,6 +194,9 @@ static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end 
{

	u8 **ptr;



	if (noreplace_smp)

		return;



	for (ptr = start; ptr < end; ptr++) {

		if (*ptr < text)

			continue;
@@ -219,6 +231,9 @@ void alternatives_smp_module_add(struct module *mod, char *name, 
	struct smp_alt_module *smp;

	unsigned long flags;



	if (noreplace_smp)

		return;



	if (smp_alt_once) {

		if (boot_cpu_has(X86_FEATURE_UP))

			alternatives_smp_unlock(locks, locks_end,
@@ -253,7 +268,7 @@ void alternatives_smp_module_del(struct module *mod) 
	struct smp_alt_module *item;

	unsigned long flags;



	if (smp_alt_once)

	if (smp_alt_once || noreplace_smp)

		return;



	spin_lock_irqsave(&smp_alt, flags);
@@ -284,7 +299,7 @@ void alternatives_smp_switch(int smp) 
	return;

#endif



	if (smp_alt_once)

	if (noreplace_smp || smp_alt_once)

		return;

	BUG_ON(!smp && (num_online_cpus() > 1));