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Date: Mon, 23 Nov 2009 13:14:28 +0200
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [Qemu-devel] Re: POST failure (loop) with isapc and seabios
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To: Sebastian Herbszt <herbszt@gmx.de>
Cc: Kevin O'Connor <kevin@koconnor.net>, qemu-devel@nongnu.org

On Sun, Nov 22, 2009 at 11:04:34PM +0100, Sebastian Herbszt wrote:
> Kevin O'Connor wrote:
> >On Sun, Nov 22, 2009 at 05:38:09PM +0200, Gleb Natapov wrote:
> >>On Sun, Nov 22, 2009 at 04:31:24PM +0100, Sebastian Herbszt wrote:
> >>>    // Write protect bios memory.
> >>>    make_bios_readonly();
> >>Hmmm. How is tpr patching works then? It relies on ability of a guest to
> >>write into BIOS memory region. Need to retest if it actually works I
> >>guess.
> >
> >The last time I looked, the TPR patching backend forced the "vapic"
> >pages to be writable (effectively overriding the bios decision to make
> >it readonly).
> 
> Does the TPR thing have to live in the optionrom/bios space or can it be moved
> somewhere else like just below 4GB (some other kvm stuff is already there) ?
> 
It needs to be in a memory that is mapped by WindowsXP kernel (but not
used by it). WindowsXP maps optionrom/bios memory, but AFAIK not e820 memory.

--
			Gleb.