1MCELOG(8) Linux's Administrator's Manual MCELOG(8)
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6 mcelog - Print machine check log from x86-64 kernel.
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9 mcelog [--syslog] [--k8|--p4|--generic] [--ignorenodev] [--dmi] [--fil‐
10 ter] [device]
11 mcelog [--k8|--p4|--generic] --ascii
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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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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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68 /dev/mcelog (char 10, minor 227)
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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)