Re: [Xen-devel] swap dom0 and domU Gfx's

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> I am really interested in the possibility of having domU take direct
> control of the graphic card and leave dom0 with the virtual GFx. I'm sure
> some of you know about Folding at Home (FAH). Its a DC project run by
> Stanford University, to simulate protein folding. More info can be found at
> http://folding.stanford.edu . They have a GPU client that runs on ATI based
> GFx under windows only. I am interested in getting the client working in
> windows via xen.
>
> In order for this, windows needs to see and access the Gfx itself. I posted
> on the folding forums and it was stated that the GPU client need to use the
> ATI drivers which in turn need to be able to see and access the physical
> GFx.

The problem here is that Windows only runs under Xen using Full 
Virtualisation, and it's not possible to assign physical devices directly to 
fully virtualised guests.

This sort of thing requires more hardware support in the form of an IOMMU.

> I'm just learning xen but I understand the basics. It seems like a near
> impossible task but to me it seem that we should be able to alter the xen
> kernel to always give your host OS the virtual GFx while saving the GFx for
> the to be guest operating system.

I think for the moment, you won't be able to achieve this.  Giving a secondary 
graphics card to a paravirtualised guest does (I *think*) work, but in this 
case the guest is probably Linux...

> I'm just wondering if anyone has thought of this before or attempted it?
> I'm not 100% sure where I need to start, except probably learn some c/c++?
> ;). I was dumb and though Java was a good language to learn.

Java is a good language to learn, just it's not so useful for most operating 
systems project.  It's great for application servers, cross platform clients 
etc (in fact, I think the XenSource commercial GUI is written in Java).

We use C for Xen and for the Linux portions.  Userspace code is a combination 
of C and Python.  Most of the higher levels of the management toolchain are 
written in Python - it's a nice language for scripting applications.

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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