Commit e583538f authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
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[PATCH] x86_64: Log machine checks from boot on Intel systems

The logging for boot errors was turned off because it was broken
on some AMD systems. But give Intel EM64T systems a chance because they are
supposed to be correct there.

The advantage is that there is a chance to actually log uncorrected
machine checks after the reset.

Signed-off-by: default avatarAndi Kleen <>
Signed-off-by: default avatarLinus Torvalds <>
parent b0bd35e6
......@@ -7,10 +7,12 @@ 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.
Disabled by default on AMD 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.
in a reboot. On Intel systems it is enabled by default.
Disable boot machine check logging.
mce=tolerancelevel (number)
0: always panic, 1: panic if deadlock possible,
2: try to avoid panic, 3: never panic or exit (for testing)
......@@ -37,7 +37,7 @@ 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;
static int mce_bootlog = 1;
* Lockless MCE logging infrastructure.
......@@ -347,7 +347,11 @@ static void __cpuinit mce_cpu_quirks(struct cpuinfo_x86 *c)
/* disable GART TBL walk error reporting, which trips off
incorrectly with the IOMMU & 3ware & Cerberus. */
clear_bit(10, &bank[4]);
/* Lots of broken BIOS around that don't clear them
by default and leave crap in there. Don't log. */
mce_bootlog = 0;
static void __cpuinit mce_cpu_features(struct cpuinfo_x86 *c)
......@@ -498,16 +502,16 @@ static int __init mcheck_disable(char *str)
/* mce=off disables machine check. Note you can reenable it later
using sysfs.
mce=TOLERANCELEVEL (number, see above)
mce=bootlog Log MCEs from before booting. Disabled by default to work
around buggy BIOS that leave bogus MCEs. */
mce=bootlog Log MCEs from before booting. Disabled by default on AMD.
mce=nobootlog Don't log MCEs from before booting. */
static int __init mcheck_enable(char *str)
if (*str == '=')
if (!strcmp(str, "off"))
mce_dont_init = 1;
else if (!strcmp(str, "bootlog"))
mce_bootlog = 1;
else if (!strcmp(str, "bootlog") || !strcmp(str,"nobootlog"))
mce_bootlog = str[0] == 'b';
else if (isdigit(str[0]))
get_option(&str, &tolerant);
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