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Date: Tue, 12 Jun 2012 19:23:52 +0200
From: Borislav Petkov <bp@amd64.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@amd64.org>, Stephane Eranian <eranian@google.com>,
        Robert Richter <robert.richter@amd.com>,
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        Andreas Herrmann <andreas.herrmann3@amd.com>,
        Dimitri Sivanich <sivanich@sgi.com>,
        Dmitry Adamushko <dmitry.adamushko@gmail.com>
Subject: Re: [PATCH] perf/x86: check ucode before disabling PEBS on
 SandyBridge
Message-ID: <20120612172352.GA4802@aftab.osrc.amd.com>
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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.

-- 
Regards/Gruss,
Boris.

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