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To: linux-kernel@vger.kernel.org
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: problems with 1gb ddr memory sticks on linux
Date: 8 Aug 2002 11:09:30 -0700
Organization: Transmeta Corporation, Santa Clara CA
Message-ID: <aiuc4q$46j$1@cesium.transmeta.com>
References: <20020808160456.GI16225@weccusa.org> <1028828840.28883.43.camel@irongate.swansea.linux.org.uk> <20020808163952.GJ16225@weccusa.org>
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Copyright: Copyright 2002 H. Peter Anvin - All Rights Reserved
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Followup to:  <20020808163952.GJ16225@weccusa.org>
By author:    "Bryan K. Walton" <thisisnotmyid@tds.net>
In newsgroup: linux.dev.kernel
>
> On Thu, Aug 08, 2002 at 06:47:20PM +0100, Alan Cox wrote:
> > 
> > Almost certainly a BIOS problem. What typically happens when you see
> > this is that the BIOS misconfigured the MTRR registers. Linux starts
> > from top of ram windows seems to start from bottom so the effect shows
> > strongly in Linux.
> > 
> > Can you post your /proc/mtrr file please
> > 
> Here you go . . .
> 
> Dimm slot 1 = 256MB DDR PC2100 and
> Dimm slot 2 = 1024MB DDR PC2100
> 
> and the /proc/mtrr shows:
> 
> casa:~# cat /proc/mtrr
> reg00: base=0x00000000 (   0MB), size= 512MB: write-back, count=1 
> 

Your BIOS didn't mark the second memory chunk as cacheable, so you're
running it uncached.  No wonder it sucks.

	-hpa
-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt	<amsp@zytor.com>
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