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

From: "Michael S. Tsirkin" <[email-masked]>
Date: Fri, 24 Jun 2022 02:59:39 -0400

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?

> Since I want to add queue_reset after queue_notify_data, I submitted
> this patch first.
> 
> Signed-off-by: Xuan Zhuo <[email-masked]>
> Acked-by: Jason Wang <[email-masked]>
> ---
>  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