> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of James Harr
> Sent: 16 January 2007 00:32
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-users] Passing a PCI-E video card to a DomU
>
> As far as I've seen (which isn't very far), opengl
> performance under most virtualization products has been
> non-existent to poor. I've been cooking up an idea to stick
> two PCIe video cards in a computer, and hand one off to a
> DomU instance (windows?), and use that for 3D rendering in
> that DomU. I'm curious to see if it's even technically
> possible (I wasn't sure if VMX guests can handle raw PCI
> devices), and if anyone has attempted it before and what
> they've run into. The idea is that if this works (and well),
> it'd be a good excuse for me to consolidate my computers into
> one big fast machine instead of spreading my money out across
> 2 or 3 machines. I went through a few pages of google
> results, saw a lot of talk, but no one who's done it yet.
>
> Any information on this topic would be helpful.
Passing any PCI device (PCI, PCI-x, PCI-e, AGP) to a HVM (VMX/SVM)
domain doesn't work. There's no way to pass it, but that's not the hard
part to solve. The hard part is to translate the guest physical
addresses to machine physical. In the future chipsets/processors, there
will be IOMMU support, which means that the address translation can be
done in hardware. But so far, this isn't available in hardware, and the
software isn't actually aware that what it thinks is the memory address
isn't REALLY the physical address of the memory, so it can't fix it.
There is a theoretical possibility of writing a virtual-aware driver,
but considering the complexity of graphics drivers for reasonably modern
graphics hardware, I'd say it will take longer to get that sorted than
it does to wait for hardware to arrive (should be available this year or
so, I think - but that's not a promise, I don't have access to plans for
either AMD or Intels future products). [The source code for a modern
graphics driver is in the same size-order as a Linux kernel with all
it's drivers, give or take a bit].
--
Mats
>
> Thanks,
> James Harr
>
>
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