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Date: Thu, 24 Jan 2008 16:11:52 -0800
From: Jeremy Fitzhardinge <jeremy@goop.org>
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To: "H. Peter Anvin" <hpa@zytor.com>
CC: Ian Campbell <ijc@hellion.org.uk>, Ingo Molnar <mingo@elte.hu>,
       =?UTF-8?B?TWlrYSBQZW50dGlsw6Q=?= <mika.penttila@kolumbus.fi>,
       linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
       Ingo Molnar <mingo@redhat.com>,
       "Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH] x86: Construct 32 bit boot time page tables in native
 format.
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H. Peter Anvin wrote:
> Yeah, I'm aware of this particular piece of Xen braindamage, and 
> although I had some very unkind words to say about it, it mirrors what 
> we have to do for the !PAE case anyway, so it can be sort of glossed 
> over.

Sort of.  If Xen weren't an issue, then both cases are a matter of 
copying a set of entries from one place in the pgd to another.

It would be easy enough to add some code on xen side to look for pmd 
aliases when using/pinning a pagetable, and allocate'n'copy a new pmd 
page as needed.  That way the core code can ignore the issue.

    J