1MCELOG(8)               Linux's Administrator's Manual               MCELOG(8)
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NAME

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

9       mcelog [--syslog] [--k8|--p4|--generic] [--ignorenodev] [--dmi] [--fil‐
10       ter] [device]
11       mcelog [--k8|--p4|--generic] --ascii
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DESCRIPTION

14       Linux x86-64 kernels since 2.6.4 don't print recoverable machine  check
15       errors to the kernel log anymore. Instead they are saved into a special
16       kernel buffer accessible using /dev/mcelog.  mcelog  reads  /dev/mcelog
17       and  prints the stored machine check records to stdout. Then the stored
18       machine check records in the kernel buffer are deleted.
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20       When the --syslog option is specified redirect output to system log.
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22       When --k8 is specified assume the events  are  for  a  AMD  Opteron  or
23       Athlon  64  or Athlon FX CPU.  With --p4 is specified assume the events
24       are for a Intel Pentium 4 or Intel Xeon.  When --generic all the fields
25       are dumped without CPU specific decoding.  Default is to decode for the
26       CPU mcelog is running on.
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28       With the --dmi option mcelog will look up  the  addresses  reported  in
29       machine  checks  in  the SMBIOS/DMI tables of the BIOS.  This can some‐
30       times tell you which DIMM or memory controller has developed a problem.
31       More  often  the  information  reported by the BIOS is either subtly or
32       obviously wrong or useless.  This option requires that mcelog has  read
33       access  to  /dev/mem  (normally  requires  root)  and  runs on the same
34       machine in the same hardware configuration as when  the  machine  check
35       event happened.
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37       When --ignorenodev is specified then mcelog will exit silently when the
38       device cannot be opened. This is useful in virtualized environment with
39       limited devices.
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41       When  --filter is specified mcelog will filter out known broken machine
42       check events.
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44       When a device is specified the machine check logs are read from  device
45       instead of the default /dev/mcelog.
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47       With the --ascii option mcelog decodes a fatal machine check panic gen‐
48       erated by the kernel ("CPU n: Machine Check Exception  ...")  in  ASCII
49       from  stdout.   This is useful to make sense of the hexadecimal numbers
50       in there.  Note that when the panic comes from a different machine than
51       where mcelog is running on you might need to specify the correct archi‐
52       tecture ( --k8 or --p4 ).
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NOTES

56       The kernel prefers old messages over new. If the log  buffer  overflows
57       only old ones will be kept.
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59       The exact output depends on the CPU.
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61       This program should be run regularly from cron to collect machine check
62       events.
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64       SMBIOS/DMI output is very unreliable and often wrong. Not Linux's fault
65       - complain to your motherboard vendor.
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FILES

68       /dev/mcelog (char 10, minor 227)
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SEE ALSO

71       AMD  x86-64 architecture programmer's manual, Volume 2, System program‐
72       ming
73       IA32 Intel Architecture Software developer's manual, Volume  3,  System
74       programming guide
75       Datasheet of your CPU.
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79SuSE Labs                          Mar 2004                          MCELOG(8)
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