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    SubjectRe: [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge
    On Tue, 2012-06-12 at 19:23 +0200, Borislav Petkov wrote:
    > On Tue, Jun 12, 2012 at 07:18:13PM +0200, Peter Zijlstra wrote:
    > > But the ucode loader can be (ab)used to only update one of the many
    > > CPUs.
    > Not if you don't support mixed ucode revisions. In that case, you want
    > the same ucode patch applied to _all_ cores on the system. Otherwise,
    > random freezes, explosions and other cataclysmic events can happen.

    You want, yes, but afaict the stuff in
    arch/x86/kernel/microcode_core.c:reload_store means you can force a
    single cpu to update while leaving the others alone.

    Afaict this is not a sane thing to do, but quite possible.

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      Last update: 2012-06-13 01:41    [W:0.020 / U:5.948 seconds]
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