Re: [dpdk-dev] [PATCH] vhost: return ready when at least 1 vring is configured

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Hi Changpeng,

On 9/1/20 9:07 AM, Changpeng Liu wrote:
> Commit d0fcc38f "vhost: improve device readiness notifications"
> needs at least 2 vrings before changing the device state to
> ready, this is fine for NET device but not correct for BLK
> device.
> 
> The number of vring required should be based on the device
> type, e.g. virtio_scsi device needs at least 3 vrings, and
> virtio_net needs at least 2 vrings, virtio_blk needs at least
> 1 vring. So instead of doing it in vhost library it's better
> that the application who uses this library do this check.
> 
> Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
> ---
>  lib/librte_vhost/vhost_user.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index c3c924f..4d1883c 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -1343,7 +1343,7 @@
>  	       vq->enabled;
>  }
>  
> -#define VIRTIO_DEV_NUM_VQS_TO_BE_READY 2u
> +#define VIRTIO_DEV_NUM_VQS_TO_BE_READY 1u

I think it would be better to rely on VIRTIO_DEV_BUILTIN_VIRTIO_NET to
know whether it should wait for 1 or 2 queues to determine if ready.


>  static int
>  virtio_is_ready(struct virtio_net *dev)
>