linux-kernel - Re: [PATCH] x86/AMD: Apply Erratum 688 fix when BIOS doesn't

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Date:   Sun, 22 Oct 2017 14:14:21 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     X86 ML <x86@...nel.org>, Sherry Hurwitz <sherry.hurwitz@....com>,
        Yazen Ghannam <Yazen.Ghannam@....com>, mirh@...tonmail.ch,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/AMD: Apply Erratum 688 fix when BIOS doesn't


* Borislav Petkov <bp@...en8.de> wrote:

> On Sun, Oct 22, 2017 at 01:04:38PM +0200, Ingo Molnar wrote:
> > Any objections to me adding a printk message that we applied a fix?
> > 
> > 	pr_info("x86/cpu/AMD: CPU erratum 688 worked around\n");
> > 
> > or so?
> > 
> > That would also create some pressure for customers to prod manufacturers to prod 
> > BIOS makers to fix the erratum in a BIOS update or so.
> 
> Adding that would be purely useless because F14h is long out of
> production AFAIK. Especially those earlier models.

I've still added it, just out of principle - every time the kernel modifies low 
level state in a rare fashion we should advertise it:

	pr_info("x86/cpu/AMD: CPU erratum 688 worked around\n");

if it doesn't matter (which is likely as you say) then the message won't matter 
really.

Thanks,

	Ingo