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From:   Jason Wang <jasowang@redhat.com>
Date:   Thu, 9 Sep 2021 17:32:20 +0800
Message-ID: <CACGkMEuSX6McCf2hcZJNKVj_1errDQGN9uPGhYWo55fsB5NKBw@mail.gmail.com>
Subject: Re: [PATCH 5/6] vdpa: add get_vq_num_unchangeable callback in vdpa_config_ops
To:     "Michael S. Tsirkin" <mst@redhat.com>
Cc:     Wu Zongyong <wuzongyong@linux.alibaba.com>,
        virtualization <virtualization@lists.linux-foundation.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        wei.yang1@linux.alibaba.com
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On Thu, Sep 9, 2021 at 5:18 PM Michael S. Tsirkin <mst@redhat.com> 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@linux.alibaba.com> 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
>