Re: [PATCH v3 0/3] virtio DMA API core stuff
From: David Woodhouse
Date: Wed Oct 28 2015 - 10:13:56 EST
On Wed, 2015-10-28 at 16:05 +0200, Michael S. Tsirkin wrote:
> Short answer - platforms need a way to discover, and express different
> security requirements of different devices.
Sure. PLATFORMS need that. Do not let it go anywhere near your device
drivers. Including the virtio drivers.
> If they continue to lack that, we'll need a custom API in virtio,
> and while this seems a bit less elegant, I would not see that as
> the end of the world at all, there are not that many virtio drivers.
No. If they continue to lack that, we fix them. This is a *platform*
issue. The DMA API shall do the right thing. Do not second-guess it.
(From the other mail)
> > > OK so I guess that means we should prefer a transport-specific
> > > interface in virtio-pci then.
> > Why?
> Because you said you are doing something device tree specific for
> ARM, aren't you?
Nonono. The ARM platform code might do that, and the DMA API on ARM
*might* give you I/O virtual addresses that look a lot like the
physical addresses you asked it to map. That's none of your business.
Drivers use DMA API. No more talky.
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