Re: [Xen-devel] Support for SSE/MMX instructions.

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 21 Apr 2006, at 14:26, Petersson, Mats wrote:

> > I don't think so. Best would be to move all HVM I/O emulation
> > to the common Xen emulator (x86_emulate.c) and add the needed
> > emulation there.
> I've looked a little bit at doing that - and it would probably make
> sense to merge x86_emulate and the hvm handle_mmio() code, but there 
> are
> some stuff done in the handle_mmio() code that isn't done in
> x86_emulate. I'll look a little further to see if I can make something
> out of it [it's clearly not very clever to have two pieces of code that
> decodes/emulates instructions!]
The main downsides to moving to x86_emulate are that it looks like movs 
emulation would be slower (but we can optimise that if it matters), and 
that you'll also need a copy of the emulator in qemu-dm (since there's 
no split decode/emulation -- but I consider that a good thing).
Certainly in terms of range of instructions emulated, x86_emulate wins 
by far. It pains me to see new instructions trickling into the HVM 
emulator(s)...
 -- Keir


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