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Date: Mon, 28 Apr 2008 22:15:06 +0200
From: Ingo Molnar <mingo@elte.hu>
To: yhlu.kernel@gmail.com
Cc: Andrew Morton <akpm@linux-foundation.org>,
       "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       Gabriel C <nix.or.die@googlemail.com>,
       Mika Fischer <mika.fischer@zoopnet.de>
Subject: Re: [PATCH] x86: mtrr cleanup for converting continuous to
	discrete layout v3
Message-ID: <20080428201506.GE15840@elte.hu>
References: <200804272337.40130.yhlu.kernel@gmail.com> <200804280206.52641.yhlu.kernel@gmail.com> <200804281244.56938.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 some 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.
> 
> v2: fix -1 for UC checking

> v3: default to disable, and need use enable_mtrr_cleanup to enable 
>     this feature
>     skip the var state change warning.
>     remove next_basek in range_to_mtrr()

a boot option is often inconvenient though - could you perhaps also make 
this a Kconfig option, with it defaulting to off? Something like 
CONFIG_MTRR_SANITIZE=y or so? That way distros can make a conscious 
decision as well whether they want this feature (for the Xorg they pick) 
or not.

	Ingo