Re: [dpdk-dev] [PATCH] virtio: fix the vq size issue

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2015-07-10 14:05, Xie, Huawei:
> Thomas:
> Could we roll back that commit or apply Changchun's patch?

It is waiting an agreement with Changchun, symbolized by an Acked-by:


> On 7/1/2015 11:53 PM, Xie, Huawei wrote:
> > On 7/1/2015 3:49 PM, Ouyang Changchun wrote:
> >> This commit breaks virtio basic packets rx functionality:
> >>   d78deadae4dca240e85054bf2d604a801676becc
> >>
> >> The QEMU use 256 as default vring size, also use this default value to calculate the virtio
> >> avail ring base address and used ring base address, and vhost in the backend use the ring base
> >> address to do packet IO.
> >>
> >> Virtio spec also says the queue size in PCI configuration is read-only, so virtio front end
> >> can't change it. just need use the read-only value to allocate space for vring and calculate the
> >> avail and used ring base address. Otherwise, the avail and used ring base address will be different
> >> between host and guest, accordingly, packet IO can't work normally.
> > virtio driver could still use the vq_size to initialize avail ring and
> > use ring so that they still have the same base address.
> > The other issue is vhost use  index & (vq->size -1) to index the ring.
> >
> >
> > Thomas:
> > This fix works but introduces slight change with original code. Could we
> > just rollback that commit?
> >
> > d78deadae4dca240e85054bf2d604a801676becc
> >
> >
> >> Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
> >> ---
> >>  drivers/net/virtio/virtio_ethdev.c | 14 +++-----------
> >>  1 file changed, 3 insertions(+), 11 deletions(-)