Re: Status of pci passthrough work?

[Amit Shah <amit.shah@redhat.com>]

Please keep me in the CC to get faster replies.

* On Monday 29 Sep 2008 06:39:26 Thomas Fjellstrom wrote:

> > > > Yes, currently you need VT-d support in hardware to assign device.
> > >
> > > So I take it the PV-DMA (or pv-dma doesn't do what I think it does...)
> > > or the other 1:1 device pass through work isn't working right now?
> >
> > pvdma does work, but the most recent patches aren't yet published (I
> > should do that). It will work for simple devices.
> >
> > 1:1 will also work.
>
> Once the trees are updated?

pvdma, yes.

I don't have the 1:1 patches in my tree as of now. Andrea maintains those 
patches.

> > > It's something I'd really like to use, but I don't have access to a
> > > platform with a hardware iommu. Though I might be able to pick up a
> > > replacement board for my new server with the SB750 southbridge which
> > > supposedly has AMD's new iommu hardware in it, but I haven't seen any
> > > evidence that kvm or linux supports it.
> >
> > Linux 2.6.27 onwards supports AMD IOMMU. kvm (and device assignment)
> > support for AMD IOMMU doesn't exist yet, but work is planned to start
> > soon.
>
> What does the kernel supporting it help a person wanting to use it to pass
> through devices to guests if kvm doesn't support it? Also, what would the
> kernel use it for in that case?

That's right; that was just to give you an idea of how things are progressing.

> Its rather hard to find the patches from before I joined the list, most
> archives don't keep attachments.

Sure; look for an update next week.

> Thanks for the heads up, and all the work on this stuff :)

You're welcome and it's always good to hear from users.