Re: [dpdk-dev] [PATCH 2/3] net/virtio_user: fix wrong sequence of messages

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

On Fri, Sep 09, 2016 at 02:24:20PM +0800, Tan, Jianfeng wrote:
> 
> 
> On 9/9/2016 2:03 PM, Yuanhan Liu wrote:
> >>GET_PROTOCOL_FEATURES
> >>is not supported yet. I see those features in PROTOCOL_FEATURES is for live
> >>migration (right?).
> >Not exactly. PROTOCOL_FEATURES was firstly introduced while MQ was
> >enabled. Thus it's no wonder MQ is the first protocol feature vhost
> >user supports:
> >
> >     [yliu@yliu-dev ~/dpdk]$ gg PROTOCOL_F_ lib/librte_vhost/
> >     lib/librte_vhost/vhost_user.h:46:#define VHOST_USER_PROTOCOL_F_MQ 0
> >     lib/librte_vhost/vhost_user.h:47:#define VHOST_USER_PROTOCOL_F_LOG_SHMFD 1
> >     lib/librte_vhost/vhost_user.h:48:#define VHOST_USER_PROTOCOL_F_RARP 2
> >
> >	--yliu
> 
> OK, I got it. The maximum of queue pair number is now a parameter of
> virtio_user, but we need to depend on PROTOCOL_FEATURES (further,
> VHOST_USER_GET_QUEUE_NUM) to maximum queue pair number that vhost can
> support.
> 
> Just wonder why not QEMU depends on (1ULL << VIRTIO_NET_F_MQ) inside
> features to do that?

VIRTIO_NET_F_MQ belongs to virtio spec, while VHOST_USER_PROTOCOL_F_MQ
belongs to vhost-user spec.

	--yliu