mcelog - Print machine check log from x86-64 kernel.

mcelog [--syslog] [--k8|--p4|--generic] [device]

mcelog [--k8|--p4|--generic] --ascii

Linux x86-64 kernels since 2.6.4 don't print recoverable machine check errors to the kernel log anymore. Instead they are saved into a special kernel buffer accessible using /dev/mcelog. mcelog reads /dev/mcelog and prints the stored machine check records to stdout. Then the stored machine check records in the kernel buffer are deleted.

When the --syslog option is specified redirect output to system log.

When --k8 is specified assume the events are for a AMD Opteron or Athlon 64 or Athlon FX CPU. With --p4 is specified assume the events are for a Intel Pentium 4 or Intel Xeon. When --generic all the fields are dumped without CPU specific decoding. Default is to decode for the CPU mcelog is running on.

When a device is specified the machine check logs are read from device instead of the default /dev/mcelog.

With the --ascii option mcelog decodes a fatal machine check message ("CPU n: Machine Check Exception ...") in ASCII from stdout. This is useful to make sense of the hexadecimal numbers there.

The kernel prefers old messages over new. If the log buffer overflows only old ones will be kept.

The exact output depends on the CPU.

This program should be run regularly from cron to collect machine check events.

/dev/mcelog (char 10, minor 227)

AMD x86-64 architecture programmer's manual, Volume 2, System programming

IA32 Intel Architecture Software developer's manual, Volume 3, System programming guide

Datasheet of your CPU.