MCE 機能を無効にする方法
Environment
- Red Hat Enterprise Linux
Issue
- MCE 機能を無効にするにはどうすればいいですか?
- mcelogd サービスをオフにしても、/var/log/mcelog ファイルにコンテンツが残っているのはなぜですか?
Resolution
/boot/grub/grub.cfgに次の項目を追加します。
mce=off
- kernel-doc パッケージから:
Documentation/x86/x86_64/boot-options.txt
Machine check
Please see Documentation/x86/x86_64/machinecheck for sysfs runtime tunables.
mce=off
Disable machine check
mce=no_cmci
Disable CMCI(Corrected Machine Check Interrupt) that
Intel processor supports. Usually this disablement is
not recommended, but it might be handy if your hardware
is misbehaving.
Note that you'll get more problems without CMCI than with
due to the shared banks, i.e. you might get duplicated
error logs.
mce=dont_log_ce
Don't make logs for corrected errors. All events reported
as corrected are silently cleared by OS.
This option will be useful if you have no interest in any
of corrected errors.
mce=ignore_ce
Disable features for corrected errors, e.g. polling timer
and CMCI. All events reported as corrected are not cleared
by OS and remained in its error banks.
Usually this disablement is not recommended, however if
there is an agent checking/clearing corrected errors
(e.g. BIOS or hardware monitoring applications), conflicting
with OS's error handling, and you cannot deactivate the agent,
then this option will be a help.
mce=bootlog
Enable logging of machine checks left over from booting.
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. On Intel systems it is enabled by default.
mce=nobootlog
Disable boot machine check logging.
mce=tolerancelevel[,monarchtimeout] (number,number)
tolerance levels:
0: always panic on uncorrected errors, log corrected errors
1: panic or SIGBUS on uncorrected errors, log corrected errors
2: SIGBUS or log uncorrected errors, log corrected errors
3: never panic or SIGBUS, log all errors (for testing only)
Default is 1
Can be also set using sysfs which is preferable.
monarchtimeout:
Sets the time in us to wait for other CPUs on machine checks. 0
to disable.
nomce (for compatibility with i386): same as mce=off
Everything else is in sysfs now.
Root Cause
- RHEL6 では、cron ジョブによって/var/log/mcelog に mcelog が再生成されるため、mcelogd サービスを停止するだけでは不十分です。
カーネルパラメーター行に mce=off を追加すると、/usr/sbin/mcelog コマンドは実行できなくなります。
$ cat /etc/cron.hourly/mcelog.cron
#!/bin/bash
/usr/sbin/mcelog --ignorenodev --filter >> /var/log/mcelog
- systemd サービスは RHEL7/8 で mcelog を保存します。
$ cat /etc/cron.hourly/mcelog.cron
#!/bin/bash
# Disabled by default on Fedora since this is run as daemon
# using the mcelog.service systemd configuration entries.
#/usr/sbin/mcelog --ignorenodev --filter >> /var/log/mcelog
# systemctl status mcelog
● mcelog.service - Machine Check Exception Logging Daemon
Loaded: loaded (/usr/lib/systemd/system/mcelog.service; enabled; vendor preset: enabled)
Active: active (running) since Tue 2019-11-05 18:52:38 EST; 2 weeks 6 days ago
Main PID: 1174 (mcelog)
Tasks: 1
CGroup: /system.slice/mcelog.service
└─1174 /usr/sbin/mcelog --ignorenodev --daemon --syslog
Nov 05 18:52:38 testjay systemd[1]: Starting Machine Check Exception Logging Daemon...
Nov 05 18:52:38 testjay systemd[1]: Started Machine Check Exception Logging Daemon.
Diagnostic Steps
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