linux-kernel - Re: [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge

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Message-ID: <20120612210436.GG11137@aftab.osrc.amd.com>
Date:	Tue, 12 Jun 2012 23:04:36 +0200
From:	Borislav Petkov <bp@...64.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Stephane Eranian <eranian@...gle.com>,
	linux-kernel@...r.kernel.org, andi@...stfloor.org, mingo@...e.hu,
	ming.m.lin@...el.com, "Yu, Fenghua" <fenghua.yu@...el.com>
Subject: Re: [PATCH] perf/x86: check ucode before disabling PEBS on
 SandyBridge

On Tue, Jun 12, 2012 at 01:58:23PM -0700, H. Peter Anvin wrote:
> There is a difference here. Mixed steppings or even mixed CPUs are,
> indeed, supported (even things like Nehalem + Westmere in the same
> system). However, the notion is that we should upload the *entire set*
> of microcodes to the kernel, and let it flash the appropriate one into
> each CPU.

Sure, the ucode driver both on Intel and AMD does that already by
looking at each patch in the blob. I'd expect no change to that
functionality.

> This may result in different version number on different CPUs.

Ok, understood.

Thanks.

-- 
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Boris.

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