[PATCH 0/3] virtio: Clean up scatterlists and use the DMA API

Konrad Rzeszutek Wilk
Wed, 27 Aug 2014 17:27:16 -0000

On Wed, Aug 27, 2014 at 07:46:46AM +0100, Stefan Hajnoczi
wrote:
> On Tue, Aug 26, 2014 at 10:16 PM, Andy Lutomirski <luto at
amacapital.net> wrote:
> > There are two outstanding issues.  virtio_net warns if DMA debugging
> > is on because it does DMA from the stack.  (The warning is correct.)
> > This also is likely to do something unpleasant to s390.
> > (Maintainers are cc'd -- I don't know what to do about it.)
>
> This changes the semantics of vring and breaks existing guests when
> bus address != physical address.

Isn't that what this is suppose to fix? Right now the semantics of the
vring is that bus address == physical address.

>
> Can you use a transport feature bit to indicate that bus addresses are
> used?  That way both approaches can be supported.
>
> Please also update the virtio specification:
> https://tools.oasis-open.org/version-control/browse/wsvn/virtio/
>
> Stefan