linux-kernel - Re: [PATCH] x86: trim ram need to check if mtrr is there v2

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Message-ID: <479A04AA.9040202@zytor.com>
Date:	Fri, 25 Jan 2008 07:47:54 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Yinghai Lu <yhlu.kernel@...il.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: trim ram need to check if mtrr is there v2

Ingo Molnar wrote:
> * Yinghai Lu <yhlu.kernel@...il.com> wrote:
> 
>> is_cpu(INTEL) already make sure we have mtrr_if got assigned and 
>> cpu_has_mtrr.
>>
>> may need to fix qemu instead...
> 
> no ...
> 
> lets not do non-sensical trimming of RAM, ok? Emit a warning but never 
> trim all of RAM and make the system unbootable. Trimmed RAM is something 
> that users can pester board/BIOS vendors with. Non-booting kernels is 
> something _we_ get pestered with ;-)
> 

*And* let's push a fix to Qemu/KVM as appropriate.

Last I checked Qemu never even turns caching on in %cr0, never mind gets 
the MTRRs right.  If it's advertising MTRRs, this is a problem.

	-hpa
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