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Date: Mon, 28 Apr 2008 15:08:26 +0200
From: Ingo Molnar <mingo@elte.hu>
To: yhlu.kernel@gmail.com
Cc: Andrew Morton <akpm@linux-foundation.org>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>,
       Arjan van de Ven <arjan@infradead.org>
Subject: Re: [PATCH] x86: mtrr cleanup for converting continuous to
	discrete layout v2
Message-ID: <20080428130826.GH27997@elte.hu>
References: <200804272337.40130.yhlu.kernel@gmail.com> <200804280206.52641.yhlu.kernel@gmail.com>
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* Yinghai Lu <yhlu.kernel.send@gmail.com> wrote:

> some BIOS like to use continus MTRR layout, and X driver can not add 
> WB entries for graphical cards when 4g or more RAM installed.
> 
> the patch will change MTRR to discrete.
> 
> mtrr_chunk_size= could be used to have smaller continuous block to 
> hold holes. default is 256m, could be set according to size of 
> graphics card memory.

hm.

> +static int disable_mtrr_cleanup;

i think this should be default-disabled. Touching MTRRs on a live system 
could interact with SMM and MCE handlers.

how relevant is this feature with modern Xorg? I thought modern Xorg 
would get its mappings via /sys, hence it would not have to touch MTRRs 
at all.

	Ingo