linux-kernel - Re: Windows side agrees that lowmem corruption is a problem too

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Message-ID: <4C0EA8A1.4020801@zytor.com>
Date:	Tue, 08 Jun 2010 13:31:29 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ondrej Zary <linux@...nbow-software.org>
CC:	Ingo Molnar <mingo@...e.hu>,
	Yuhong Bao <yuhongbao_386@...mail.com>,
	linux-kernel@...r.kernel.org, gregkh@...e.de
Subject: Re: Windows side agrees that lowmem corruption is a problem too

On 06/08/2010 12:22 PM, Ondrej Zary wrote:
>>
>> Yep, patterns of some silly OSD bitmap showed up in one of the corruption -
>> firmware displaying a 'you inserted a cable' kind of icon somewhere and
>> messing up the SMM code or so ...
>>
>> I agree that dis-using <1M by default is probably the sanest option.
> 
> But please limit it to newer systems only (DMI present && year > 200?). There 
> are many old machines running fine. Losing 1MB from 16MB is a bad thing.
> 

Disusing 64K is something we can do unconditionally (especially since
we're only talking about 60K -- 15 pages -- of actually usable memory
anyway.)

Dropping all the low 0.6 MB (which is what it really is) is probably
unacceptable by default, but perhaps it makes sense to use it only for
ZONE_DMA or something.

	-hpa
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