linux-kernel - Re: 4GB Physical. Less than 3GB in Linux.

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Message-ID: <46238572.5050203@s5r6.in-berlin.de>
Date:	Mon, 16 Apr 2007 16:17:22 +0200
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	Jeff Chua <jeff.chua.linux@...il.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: 4GB Physical. Less than 3GB in Linux.

Jeff Chua wrote:
> I've noticed that with 4GB physical ram, I'm only see 3098000 MB on
> the Dell 745, and 3107056MB on the IBM X60s.
> 
> I've tested with CONFIG_HIGHMEM4G=y, CONFIG_HIGHMEM64G=y,
> CONFIG_X86_PAE=y, but nothing makes any difference.
> 
> Tested on Linux 2.6.20, Linux 2.6.21-rc7.

The X60 most certainly contains a chipset which severely limits the
amount of accessible RAM due to issues with remapping of PCIe addresses.
 Intel explains it somewhere on their web presence.  A quick & lazy web
search turned this Intel paper up:
http://www.polywell.com/us/support/faq/4GB_Rev1.pdf
-- 
Stefan Richter
-=====-=-=== -=-- -==-=
http://arcgraph.de/sr/
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