[PATCH] i386: Allow boot-time disable of SMP altinstructions
Add "noreplace-smp" to disable SMP instruction replacement.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 94ce0d2..242b3a0 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1164,6 +1164,9 @@
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 @@
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]
diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c
index f096354..9b8e85a 100644
--- a/arch/i386/kernel/alternative.c
+++ b/arch/i386/kernel/alternative.c
@@ -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 @@
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 @@
{
u8 **ptr;
+ if (noreplace_smp)
+ return;
+
for (ptr = start; ptr < end; ptr++) {
if (*ptr < text)
continue;
@@ -219,6 +231,9 @@
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 @@
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 @@
return;
#endif
- if (smp_alt_once)
+ if (noreplace_smp || smp_alt_once)
return;
BUG_ON(!smp && (num_online_cpus() > 1));