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    SubjectRe: [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge
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    On Wed, 2012-06-13 at 07:00 -0700, H. Peter Anvin wrote:
    > On 06/13/2012 01:38 AM, Peter Zijlstra wrote:
    > > On Tue, 2012-06-12 at 13:58 -0700, H. Peter Anvin wrote:
    > >> even things like Nehalem + Westmere in the same system
    > >
    > > Uhm,.. how well do you expect Linux to run on a franken-system like
    > > that? I'm pretty sure perf will malfunction in such a setup.
    > >
    >
    > perf might, but I have seen such frankensystems in the field and they
    > work (although I haven't seen that particular combo, I have to admit.)

    Thing is, if we boot on the wsm, perf could fault the system with
    nonexistent MSR accesses, if we boot on the nhm worst is wrong numbers I
    think.

    I'm not really inclined to 'fix' this.. the best I'm willing to accept
    is a patch that would detect this situation and simply disable all
    hardware perf support for the platform.


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