Messages in this thread | | | Date | Tue, 1 Jul 2014 10:14:13 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2] perf/x86/intel: ignore CondChgd bit to avoid false NMI handling |
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On Mon, Jun 30, 2014 at 03:22:24PM -0700, Andi Kleen wrote: > > > > I'm also interested in the behaviour of CondChgd bit on Ivy Bridge processors. > > The intended meaning of CondChgd is that a hardware debugger has taken over the > PMU. It shouldn't really be set in other circumstances.
The SDM utterly and totally fails to mention this, please fix that.
> I think right now for perf it would be best to just ignore it. > > In theory could stop using the PMU, but if some BIOS set it it would > completely disable perf there. So better to just ignore it.
The even better option would be to kill off SMM mode, all that ever does is create problems.
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