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

Chris Wright
2010-07-15T17:25:53Z

* Avi Kivity (avi@redhat.com) wrote:
> On 07/15/2010 08:17 PM, Chris Wright wrote:
> >
> >>For emulated device, it seems like we can ignore ATS completely, no?
> >Not if you want to emulate an ATS capable device ;)
>
> What I meant was that the whole request translation, invalidate, dma
> using a translated address thing is invisible to software. We can
> emulate an ATS capable device by going through the iommu every time.

Well, I don't see any reason to completely ignore it. It'd be really
useful for testing (I'd use it that way). Esp to verify the
invalidation of the device IOTLBs.

But I think it's not a difficult thing to emulate once we have a proper
api encapsulating a device's dma request.

thanks,
-chris