"Fixing" mcelog on AMD cpu's

[Richard Shaw]

All of my computers at home are AMD based and a while ago I noticed that
the mcelog service always fails. It has been reported on BZ [1]

The easy solution was to just disable it but I wasn't sure how important it
was at the time. Turns out it's just flat out incompatible with modern AMD
processors[2,3].

So what do we do? I don't think it should be disabled since you never know
when you'll swap a hard drive or motherboard but it should have a way to
exit cleanly and just do nothing.

Basically, don't go away mad (erroring out), just go away.

I've searched the systemd help files but haven't found anything that does
this directly.

First I wondered if there was a way to use (abuse?) ExecStartPre to check
for compatibility before starting mcelog (via --is-cpu-supported) but if it
fails then the whole service fails so the result is the same.

I thought about using the error code, but grepping through the source, 1 is
used all over the place, not just for this particular problem. So making
the exit code "OK" is not an option.

Then I thought perhaps there was a way to have a separate service file to
check compatibility (mcelog-check.service?) and have it "Wants" the actual
service file. That may still be possible but I haven't figured out the
magic incantation to get that to work.

Ideas?

Thanks,
Richard

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1069652
[2] http://www.mcelog.org/faq.html#13
[3] http://www.mcelog.org/faq.html#18
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