Re: [PATCH 5/6] vdpa: add get_vq_num_unchangeable callback in vdpa_config_ops

[Jason Wang]

On Thu, Sep 9, 2021 at 5:18 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
>
> On Thu, Sep 09, 2021 at 10:55:03AM +0800, Jason Wang wrote:
> > On Wed, Sep 8, 2021 at 8:23 PM Wu Zongyong <wuzongyong@xxxxxxxxxxxxxxxxx> wrote:
> > >
> > > This new callback is used to indicate whether the vring size can be
> > > change or not. It is useful when we have a legacy virtio pci device as
> > > the vdpa device for there is no way to negotiate the vring num by the
> > > specification.
> >
> > So I'm not sure it's worth bothering. E.g what if we just fail
> > VHOST_SET_VRING_NUM it the value doesn't match what hardware has?
> >
> > Thanks
>
> More importantly is there and actual plan for supporting
> legacy devices? I don't think they currently work at a number
> of levels.

I think the answer is no, it would introduce a lot of burdens.

Thanks

>
> --
> MST
>