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Re: [Xen-devel] X86_emulate to be moved into qemu...

To: "Petersson, Mats" <Mats.Petersson@xxxxxxx>
Subject: Re: [Xen-devel] X86_emulate to be moved into qemu...
From: "Jon Smirl" <jonsmirl@xxxxxxxxx>
Date: Wed, 17 May 2006 17:45:28 -0400
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>, Xen devel list <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On 5/17/06, Petersson, Mats <Mats.Petersson@xxxxxxx> wrote:
> -----Original Message-----
> From: Jon Smirl [mailto:jonsmirl@xxxxxxxxx]
> Sent: 17 May 2006 21:46
> To: Petersson, Mats
> Cc: Keir Fraser; Xen devel list; Benjamin Herrenschmidt
> Subject: Re: [Xen-devel] X86_emulate to be moved into qemu...
> On 5/17/06, Petersson, Mats <Mats.Petersson@xxxxxxx> wrote:
> > > Hmmm... wouldn't it be nice if we didn't have a bespoke, buggy &
> > > incomplete emulator for hvm mmio. ;-)
> >
> > In the process of solving this one, I've got to (another) of the
> > blocking points...
> If Xen is going to need an x86 emulator, there is also need of a small
> x86 emulator based on klibc as part of the general Linux kernel.
> People often put video cards with x86 ROMs into PPC/Itanium
> machines since the x86 versions are half the price. The
> general idea is that during the boot process the emulator
> would run the x86 ROM and initialize these cards. The same
> code would be used to initialize secondary cards on all
> architectures. After klibc gets added to the kernel tree I'd
> also like to see the emulator and video reset program added.

Ehm, yes, but this is a much smaller emulator, as it's only emulating
instructions that are caught by page faults - so only instructions that
are doing memory accesses.

I think you could use the full x86-emulator that is part of the QEMU
project to achive what you're after, but the x86_emualte_memop() that
we're talking about here would not be even close to sufficient for
running the BIOS on a non-x86 processor.

It wasn't clear from the earlier mail that this was only a partial
emulator. We are already using the emulator from the Linux Bios
project so we'll stick with that. It would nice to reduce the number
of emulator code bases being used.

> --
> Jon Smirl
> jonsmirl@xxxxxxxxx

Jon Smirl

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