Re: [dpdk-dev] [DPDK] net/virtio: packed ring notification data feature support

["Liu, Yong" <yong.liu@intel.com>]

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Cheng Jiang
> Sent: Wednesday, December 04, 2019 11:03 PM
> To: dev@dpdk.org
> Cc: maxime.coquelin@redhat.com; Bie, Tiwei <tiwei.bie@intel.com>; Wang,
> Zhihong <zhihong.wang@intel.com>; Jiang, Cheng1 <cheng1.jiang@intel.com>
> Subject: [dpdk-dev] [DPDK] net/virtio: packed ring notification data
> feature support
> 
> This patch supports the feature that the driver passes extra data
> (besides identifying the virtqueue) in its device notifications.
> 
> Signed-off-by: Cheng Jiang <Cheng1.jiang@intel.com>
> ---
>  drivers/net/virtio/virtio_ethdev.h |  3 ++-
>  drivers/net/virtio/virtio_pci.c    | 15 ++++++++++++++-
>  drivers/net/virtio/virtio_pci.h    |  6 ++++++
>  3 files changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_ethdev.h
> b/drivers/net/virtio/virtio_ethdev.h
> index a10111758..cd8947656 100644
> --- a/drivers/net/virtio/virtio_ethdev.h
> +++ b/drivers/net/virtio/virtio_ethdev.h
> +	if (vtpci_with_feature(hw, VIRTIO_F_RING_PACKED))
> +		notify_data = ((((uint32_t)vq->vq_packed.used_wrap_counter <<
> 15) |
> +				vq->vq_avail_idx) << 16) | vq->vq_queue_index;
> +	else
> +		notify_data = ((uint32_t)vq->vq_avail_idx << 16) |
> +				vq->vq_queue_index;

Hi Cheng,
According to virtio1.1 spec, wrap counter should refer to next available descriptor.
So used_wrap_counter should be replaced with avail_wrap_counter. Sorry for late noticing. 

Thanks,
Marvin

> +	rte_write32(notify_data, vq->notify_addr);
>  }
>