[PATCH v10 25/41] virtio_pci: struct virtio_pci_common_cfg add queue_notify_data

[Xuan Zhuo]

On Fri, 24 Jun 2022 02:59:39 -0400, "Michael S. Tsirkin" <mst at redhat.com> wrote:
> On Fri, Jun 24, 2022 at 10:56:05AM +0800, Xuan Zhuo wrote:
> > Add queue_notify_data in struct virtio_pci_common_cfg, which comes from
> > here https://github.com/oasis-tcs/virtio-spec/issues/89
> >
> > For not breaks uABI, add a new struct virtio_pci_common_cfg_notify.
>
> What exactly is meant by not breaking uABI?
> Users are supposed to be prepared for struct size to change ... no?

This was a previous discussion with Jason Wang, who was concerned about
affecting some existing programs.

https://lore.kernel.org/all/CACGkMEshTp8vSP9=pKj82y8+DDQFu9tFAk1EGhMZLvXUE-OSEA@mail.gmail.com/

Thanks.

>
>
> > Since I want to add queue_reset after queue_notify_data, I submitted
> > this patch first.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> > Acked-by: Jason Wang <jasowang at redhat.com>
> > ---
> >  include/uapi/linux/virtio_pci.h | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h
> > index 3a86f36d7e3d..22bec9bd0dfc 100644
> > --- a/include/uapi/linux/virtio_pci.h
> > +++ b/include/uapi/linux/virtio_pci.h
> > @@ -166,6 +166,13 @@ struct virtio_pci_common_cfg {
> >  	__le32 queue_used_hi;		/* read-write */
> >  };
> >
> > +struct virtio_pci_common_cfg_notify {
> > +	struct virtio_pci_common_cfg cfg;
> > +
> > +	__le16 queue_notify_data;	/* read-write */
> > +	__le16 padding;
> > +};
> > +
> >  /* Fields in VIRTIO_PCI_CAP_PCI_CFG: */
> >  struct virtio_pci_cfg_cap {
> >  	struct virtio_pci_cap cap;
> > --
> > 2.31.0
>