Re: [Qemu-devel] Re: [RFC PATCH 4/7] ide: IOMMU support

Eduard - Gabriel Munteanu
2010-07-15T17:28:57Z

On Thu, Jul 15, 2010 at 10:17:10AM -0700, Chris Wright wrote:
> * Avi Kivity (avi@redhat.com) wrote:
> >
> > For emulated device, it seems like we can ignore ATS completely, no?
>
> Not if you want to emulate an ATS capable device ;)
>
> Eariler upthread I said:
>
> IOW, if qemu ever had a device with ATS support...
>
> So, that should've been a much bigger _IF_
>
> thanks,
> -chris

I think we can augment some devices with ATS capability if there are
performance gains in doing so. This doesn't seem to be a detail the
actual guest OS would be interested in, so we can do it even for devices
that existed long before the AMD IOMMU came into existence. But I'm not
really sure about this, it's just a thought.

Linux seems to be issuing IOTLB invalidation commands anyway.

Eduard