linux-kernel - Re: [tip:x86/setup] x86, setup: "glove box" BIOS calls -- infrastructure

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Message-ID: <49E367E8.7080202@zytor.com>
Date:	Mon, 13 Apr 2009 09:27:20 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Avi Kivity <avi@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Pavel Machek <pavel@....cz>, mingo@...hat.com,
	linux-kernel@...r.kernel.org, tglx@...utronix.de,
	hpa@...ux.intel.com, rjw@...k.pl, linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/setup] x86, setup: "glove box" BIOS calls --	infrastructure

Ingo Molnar wrote:
>> Yes, we could do memory checks, and ... hey, we already do that:
>>
>>    bb577f9: x86: add periodic corruption check
>>    5394f80: x86: check for and defend against BIOS memory corruption
>>
>> ... and i seem to be the one who implemented it! ;-)
> 
> s/implemented/merged+fixed :-)

Actually, what would probably be more productive than trying to track
corruption would be to drop the low 1 MB of memory before suspend to RAM
- make sure that it is as close to completely unused as possible.

All *known* cases of low memory corruption are either boot time or due
to s2ram.

I don't know how realistic it is to make the low 1 MB completely unused
over the s2ram cycle.  The trivial way of doing it is to simply not use
it -- it's only some 600K after all; a more sophisticated way would be
to explicitly constrain it to transient uses that would be dead at s2ram.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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