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Re: [Xen-devel] [RFC][PATCH] Emulate instructions in vm86 mode

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] [RFC][PATCH] Emulate instructions in vm86 mode
From: Bastian Blank <bastian@xxxxxxxxxxxx>
Date: Thu, 7 Sep 2006 15:59:51 +0200
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On Thu, Sep 07, 2006 at 02:24:33PM +0100, Keir Fraser wrote:
> On 7/9/06 14:09, "Bastian Blank" <bastian@xxxxxxxxxxxx> wrote:
> >> (INS/OUTS). What happens if you just bail to the guest's GPF handler if in
> >> vm86 mode?
> > I don't know how to do that.
> Just add 'if (vm86_mode(regs)) goto fail' to the top of
> emulate_privileged_op(). This will cause Xen to fall back to propagating the
> fault to the guest's GPF handler.

Seems to work partialy. The i810 driver can init the hardware but I get
weird artefacts. It seems that some of the memory which is used for the
cursor is overwriten by the real video output or so. Therefor I think
that one of the segment registers which the bios uses is overwriten
somewhere in this gpf handling.

Hmm, the trap bounce code clears ds and es.


                -- The Gorn, "Arena", stardate 3046.2

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