From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.fraser@eu.citrix.com>
Subject: Re: Illegal PV kernel pfm/pfn translations on PROT_NONE
	ioremaps
Date: Thu, 20 Mar 2008 11:39:26 +0000
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To: "Stephen C. Tweedie" <sct@redhat.com>
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On 19/3/08 18:52, "Keir Fraser" <keir.fraser@eu.citrix.com> wrote:

>> Yep.  There are a number of bits that could be used: for example, I
>> don't think PROT_WRITE is ever going to be set on a PROT_NONE page,
>> either.
> 
> My point is the flag would be set even when the protection is not PROT_NONE.
> It has other uses beyond fixing this bug.
> 
> I might look into doing this myself as I think it is probably the best fix for
> this issue.

...and the issue is now fixed (changeset 488) in
http://xenbits.xensource.com/staging/linux-2.6.18-xen.hg

The patch is a minimal one given the approach of using a new _PAGE_IO flag.
For example, pte_pfn() probably no longer needs to use mfn_to_local_pfn()
and could use the simpler and faster mfn_to_pfn() instead. But that belongs
in a separate patch.

 -- Keir