linux-kernel - Re: [PATCH 2/2] x86: Enable monitor/mwait on Intel if BIOS hasn't already

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Message-ID: <CAObL_7HZ_8tSfKCpoKN68O1OJczCW+dOEhRiVu-zVwWOFHj1ew@mail.gmail.com>
Date:	Wed, 3 Aug 2011 23:18:32 -0400
From:	Andrew Lutomirski <luto@....edu>
To:	Len Brown <lenb@...nel.org>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	Fenghua Yu <fenghua.yu@...el.com>, linux-acpi@...r.kernel.org
Subject: Re: [PATCH 2/2] x86: Enable monitor/mwait on Intel if BIOS hasn't already

On Wed, Aug 3, 2011 at 3:17 PM, Len Brown <lenb@...nel.org> wrote:
>> >> What machine has this BIOS bug, and are you running
>> >> the latest version of the BIOS?
>> >
>> > Intel DQ67SW, version SWQ6710H.86A.0051.2011.0413.1154.  This is not
>> > quite up-to-date -- I'll test a newer BIOS.
>>
>> SWQ6710H.86A.0053.2011.0615.1535 has the same problem.  It fixed ASPM, though :)
>>
>> Should I redo the patch with a printk to warn about the firmware bug?
>
> I would hope that a patch that _only_ prints [Firmware bug]
> should be enough.  This isn't the kind of workaround
> that we should really have to carry in the kernel.
>
> This is still a very new platform, and my guess is that
> they are actively updating the BIOS as we speak.
> I'll see if I can figure out who to talk to
> in order to make sure of that:-)

I can add a strange data point:  with TXT enabled in BIOS, fast
strings are disabled (on all CPUs, I think) and monitor/mwait is
disabled on the boot CPU.  With TXT disabled, both features are
enabled.

I'll see if my laptop does the same thing.

--Andy
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