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[PATCH] i386: Allow boot-time disable of SMP altinstructions

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

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
This commit is contained in:
Jeremy Fitzhardinge 2007-05-02 19:27:13 +02:00 committed by Andi Kleen
parent d0175ab644
commit b7fb4af06c
2 changed files with 25 additions and 4 deletions
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6
Documentation/kernel-parameters.txt
View file

@ -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]

23
arch/i386/kernel/alternative.c
View file

@ -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));