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-rw-r--r--Documentation/x86_64/boot-options.txt5
-rw-r--r--arch/x86_64/kernel/mce.c16
2 files changed, 17 insertions, 4 deletions
diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt
index 476c0c22fbb7..678e8f192db2 100644
--- a/Documentation/x86_64/boot-options.txt
+++ b/Documentation/x86_64/boot-options.txt
@@ -6,6 +6,11 @@ only the AMD64 specific ones are listed here.
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
diff --git a/arch/x86_64/kernel/mce.c b/arch/x86_64/kernel/mce.c
index 3b267c91bb0c..8aa56736cde3 100644
--- a/arch/x86_64/kernel/mce.c
+++ b/arch/x86_64/kernel/mce.c
@@ -36,6 +36,7 @@ static unsigned long bank[NR_BANKS] = { [0 ... NR_BANKS-1] = ~0UL };
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 * regs, long error_code)
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 *str)
}
/* 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;