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

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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