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Message-ID: <16952.53719.150647.638710@cargo.ozlabs.ibm.com>
Date: Thu, 17 Mar 2005 11:39:51 +1100
From: Paul Mackerras <paulus@samba.org>
To: Rik van Riel <riel@redhat.com>
Cc: Jesse Barnes <jbarnes@engr.sgi.com>,
       Keir Fraser <Keir.Fraser@cl.cam.ac.uk>, linux-kernel@vger.kernel.org,
       akpm@osdl.org, kurt@garloff.de, Ian.Pratt@cl.cam.ac.uk,
       Christian.Limpach@cl.cam.ac.uk
Subject: Re: [PATCH] Xen/i386 cleanups - AGP bus/phys cleanups
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Rik van Riel writes:

> Thing is, the rest of the kernel uses virt_to_phys for
> two different things.  Only one of them has to do with
> the real physical address, the other is about getting
> the page frame number.

So fix the places that are using virt_to_phys to get the page frame
number to use virt_to_pfn instead. :)

> On native x86, x86-64 and others, the page frame number
> and physical address are directly related to each other.
> Under Xen, however, the two are different - and the
> AGPGART really needs to have the physical address ;)

If Xen is letting the kernel program the GART, you just lost any
memory isolation between partitions you might have been trying to
enforce. :)

Paul.
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