From: Andi Kleen <ak@muc.de>
Don't log machine check events left over from boot.
Too many BIOS leave bogus events in there.
This unfortunately also makes it impossible to log events that caused a
reboot. For people with non broken BIOS there is mce=bootlog
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
Documentation/x86_64/boot-options.txt | 5 +++++
arch/x86_64/kernel/mce.c | 16 ++++++++++++----
2 files changed, 17 insertions(+), 4 deletions(-)
diff -puN arch/x86_64/kernel/mce.c~x86_64-ignore-machine-checks-from-boot-time arch/x86_64/kernel/mce.c
--- devel/arch/x86_64/kernel/mce.c~x86_64-ignore-machine-checks-from-boot-time 2005-08-05 13:21:58.000000000 -0700
+++ devel-akpm/arch/x86_64/kernel/mce.c 2005-08-05 13:21:58.000000000 -0700
@@ -36,6 +36,7 @@ static unsigned long bank[NR_BANKS] = {
static unsigned long console_logged;
static int notify_user;
static int rip_msr;
+static int mce_bootlog;
/*
* Lockless MCE logging infrastructure.
@@ -197,10 +198,11 @@ void do_machine_check(struct pt_regs * r
rdmsrl(MSR_IA32_MC0_ADDR + i*4, m.addr);
mce_get_rip(&m, regs);
- if (error_code != -1)
+ if (error_code >= 0)
rdtscll(m.tsc);
wrmsrl(MSR_IA32_MC0_STATUS + i*4, 0);
- mce_log(&m);
+ if (error_code != -2)
+ mce_log(&m);
/* Did this bank cause the exception? */
/* Assume that the bank with uncorrectable errors did it,
@@ -315,7 +317,7 @@ static void mce_init(void *dummy)
/* Log the machine checks left over from the previous reset.
This also clears all registers */
- do_machine_check(NULL, -1);
+ do_machine_check(NULL, mce_bootlog ? -1 : -2);
set_in_cr4(X86_CR4_MCE);
@@ -476,11 +478,17 @@ static int __init mcheck_disable(char *s
}
/* mce=off disables machine check. Note you can reenable it later
- using sysfs */
+ using sysfs.
+ mce=bootlog Log MCEs from before booting. Disabled by default to work
+ around buggy BIOS that leave bogus MCEs. */
static int __init mcheck_enable(char *str)
{
+ if (*str == '=')
+ str++;
if (!strcmp(str, "off"))
mce_dont_init = 1;
+ else if (!strcmp(str, "bootlog"))
+ mce_bootlog = 1;
else
printk("mce= argument %s ignored. Please use /sys", str);
return 0;
diff -puN Documentation/x86_64/boot-options.txt~x86_64-ignore-machine-checks-from-boot-time Documentation/x86_64/boot-options.txt
--- devel/Documentation/x86_64/boot-options.txt~x86_64-ignore-machine-checks-from-boot-time 2005-08-05 13:21:58.000000000 -0700
+++ devel-akpm/Documentation/x86_64/boot-options.txt 2005-08-05 13:21:58.000000000 -0700
@@ -6,6 +6,11 @@ only the AMD64 specific ones are listed
Machine check
mce=off disable machine check
+ mce=bootlog Enable logging of machine checks left over from booting.
+ Disabled by default because some BIOS leave bogus ones.
+ If your BIOS doesn't do that it's a good idea to enable though
+ to make sure you log even machine check events that result
+ in a reboot.
nomce (for compatibility with i386): same as mce=off
_