linux-kernel - Re: [tip:x86/urgent] x86/cpu/AMD: Apply the Erratum 688 fix when the BIOS doesn't

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Date:   Sun, 22 Oct 2017 16:01:38 +0200
From:   Boris Petkov <bp@...e.de>
To:     Peter Zijlstra <peterz@...radead.org>, hpa@...or.com,
        torvalds@...ux-foundation.org, tglx@...utronix.de,
        mingo@...nel.org, Yazen.Ghannam@....com, mirh@...tonmail.ch,
        sherry.hurwitz@....com, stable@...r.kernel.org,
        linux-kernel@...r.kernel.org
CC:     linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/urgent] x86/cpu/AMD: Apply the Erratum 688 fix when the BIOS doesn't

On October 22, 2017 3:04:29 PM GMT+02:00, Peter Zijlstra <peterz@...radead.org> wrote:
>I realize this is an erratum work around, but would it be too much to
>ask for a small comment explaining the magic values?

Revision guide doesn't state what those bits are. By the looks of it, they could be some sort of chicken bits turning off something.

>Except for all CPUs that were not online at this point in time... So
>suppose I boot with a limited number of CPUs and then later bring up
>the
>rest, bad things happen.

Well, those are small laptops and they're 1 or 2 CPUs tops and you really really really have to try to shoot yourself in the foot...


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