Re: [PATCH 1/8] virtio: add request_vqs/free_vqs operations

Michael S. Tsirkin
2009-05-04T11:53:54Z

On Mon, May 04, 2009 at 09:02:20PM +0930, Rusty Russell wrote:
> On Mon, 27 Apr 2009 10:01:53 pm Michael S. Tsirkin wrote:
> > This adds 2 new optional virtio operations: request_vqs/free_vqs. They will be
> > used for MSI support, because MSI needs to know the total number of vectors
> > upfront.
> >
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>
> Hi Michael,

Hi Rusty,

> Thanks for this work! But this interface is horrible. Either probe for the
> number of vqs in virtio_pci, or change find_vq to
>
> int (*find_vqs)(struct virtio_device *, unsigned max,
> struct virtqueue *vqs[]);

I'm happier with the later option: it's easy for a host to expose
support for a very large number of vqs, and I don't want them to
waste resources if guest does not use them.

Thanks for the feedback!

> Thanks,
> Rusty.

--
MST