Re: [virtio-dev] packed ring layout proposal

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Sep 16, 2016 at 10:46:52AM +0100, Stefan Hajnoczi wrote:
> On Fri, Sep 16, 2016 at 01:39:15AM +0300, Michael S. Tsirkin wrote:
> > The idea is to have a r/w descriptor in a ring structure,
> > replacing the used and available ring, index and descriptor
> > buffer.
> 
> This is probably obvious but:
> 
> Why is the desc.index field needed?
> 
> The index field would be needed if the driver had to jump over a DESC_HW
> descriptor when adding descriptors, but that doesn't seem necessary
> since the device is supposed to overwrite descriptors in ascending ring
> order when they complete out-of-order.
> 
> Stefan


This should be desc.id. The point is to be able to
figure out which descriptor was used. I'll rename it.