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    SubjectRe: [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge
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    On Fri, Jun 8, 2012 at 12:00 PM, Peter Zijlstra <peterz@infradead.org> wrote:
    > On Fri, 2012-06-08 at 11:35 +0200, Ingo Molnar wrote:
    >> * Peter Zijlstra <peterz@infradead.org> wrote:
    >>
    >> > On Thu, 2012-06-07 at 12:48 +0200, Stephane Eranian wrote:
    >> > > >> The warning could also be done on boot. But the check has to be done
    >> > > >>  when the event is created.
    >> > > >
    >> > > > Is this because of the ucode loader not having done its thing yet etc..?
    >> >
    >> > Ah, its because you can update ucode at runtime of course.
    >> >
    >> > A quick look at the ucode loader doesn't show it having a
    >> > notifier either, so then yeah we need to check on every event
    >> > creation :/
    >> >
    >> > Or we could put a hook in the ucode loader.
    >>
    >> I'd really suggest the latter - I doubt this will be our only
    >> ucode dependent quirk, going forward ...
    >
    > Yeah, am in the middle of writing that..

    I am fine with that. As I found out yesterday, the reality is that the
    ucode version for SNB vs. SNB-EP differ, so with this mechanism
    we could customize the callback per CPU model number more easily.
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