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Date: Tue, 19 Apr 2016 19:04:43 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
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Subject: Re: [PATCH RFC] fixup! virtio: convert to use DMA api
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On Tue, Apr 19, 2016 at 09:00:27AM -0700, Andy Lutomirski wrote:
> On Apr 19, 2016 2:13 AM, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> >
> >
> > I guess you are right in that we should split this part out.
> > What I wanted is really the combination
> > PASSTHROUGH && !PLATFORM so that we can say "ok we don't
> > need to guess, this device actually bypasses the IOMMU".
> 
> What happens when you use a device like this on Xen or with a similar
> software translation layer?

I think you don't use it on Xen since virtio doesn't bypass an IOMMU there.
If you do you have misconfigured your device.

-- 
MST