Messages in this thread | | | Date | Mon, 30 Mar 2009 11:42:12 +0200 | From | Andi Kleen <> | Subject | Re: [PATCH -tip 1/3] x86, mce: Add mce_threshold option for intel cmci |
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> Makes sense. CMCI is a new CPU feature so having boot controls to > disable it is generally a good idea - while still having old-style > MCE support in place.
That's not what the patch does unfortunately.
> Applied to tip:x86/mce2, thanks Hidetoshi!
If you fear that CMCI is misbehaving you would need a different option to turn it off completely, setting the threshold doesn't help. For example there are banks that only support threshold == 1 and when the enable bit is on then no matter what value you write in there events will cause CMCIs. So this patch cannot turn them off.
To turn it off you would need to disable the CMCI enable bit completely.
I have no problems in principle with a mce=nocmci that does that but that would be a different patch.
However I expect that this will be not a good idea to ever use on Nehalem class systems at least because without CMCI the machine check code cannot handle shared banks correctly and you'll get duplicated events from them. And on non Nehalem systems there is no CMCI anyways, so it'll be always off.
-Andi
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