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Date: Mon, 20 May 2013 16:36:43 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v5] virtio-net: dynamic network offloads
	configuration
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, Jason Wang <jasowang@redhat.com>, qemu-devel@nongnu.org, Gerd Hoffmann <kraxel@redhat.com>, Amos Kong <akong@redhat.com>, Andreas =?iso-8859-1?Q?F=E4rber?= <afaerber@suse.de>, KONRAD Frederic <fred.konrad@greensocs.com>

On Mon, May 20, 2013 at 12:52:57PM +0200, Paolo Bonzini wrote:
> Il 20/05/2013 10:18, Michael S. Tsirkin ha scritto:
> > diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
> > index beeead7..b315ac9 100644
> > --- a/include/hw/virtio/virtio-net.h
> > +++ b/include/hw/virtio/virtio-net.h
> > @@ -31,6 +31,8 @@
> >  /* The feature bitmap for virtio net */
> >  #define VIRTIO_NET_F_CSUM       0       /* Host handles pkts w/ partial csum */
> >  #define VIRTIO_NET_F_GUEST_CSUM 1       /* Guest handles pkts w/ partial csum */
> > +#define VIRTIO_NET_F_CTRL_GUEST_OFFLOADS 2 /* Control channel offload
> > +                                         * configuration support */
> 
> Any reason not to use 22?

There are several
- 22 is already used by VIRTIO_NET_F_MQ
- guest drivers (in development) and spec upstream both use 2

> 
> Is there any hidden reason why bits 2..4 are not used in the spec?
> 
> Paolo

I don't know for sure, sorry.
BTW please send questions on virtio spec on virtio
mailing list, not here.

Thanks!

-- 
MST