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From: William Lee Irwin III <wli@holomorphy.com>
To: Timothy Miller <miller@techsource.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: PCI mapping on large memory 32-bit machines
Date: Mon, 19 May 2003 15:59:04 -0700	[thread overview]
Message-ID: <20030519225904.GI8978@holomorphy.com> (raw)
In-Reply-To: <3EC91F3B.8010005@techsource.com>

On Mon, May 19, 2003 at 02:15:23PM -0400, Timothy Miller wrote:
> On x86 with PAE and 4 gigs of RAM or more, where do memory-mapped I/O 
> devices get mapped (in the physical address space)?  Most PCI devices 
> can't handle 64-bit addresses.  Can PC chipsets physically remap some of 
> the RAM to above 4 gig?  Or do you just lose that much RAM?  If both RAM 
> and some I/O device are mapped to the same location, isn't there a conflict?

AFAIK most (if not all) of that lands below 4GB in extant chipsets/BIOS's.

Remapping above 4GB is possible but various things would probably barf.


-- wli

      parent reply	other threads:[~2003-05-19 22:46 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-05-19 18:15 PCI mapping on large memory 32-bit machines Timothy Miller
2003-05-19 18:25 ` Richard B. Johnson
2003-05-19 22:59 ` William Lee Irwin III [this message]

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