Re: [Qemu-devel] [RFC v2 1/2] docs: vhost-user: add in-band kick/call messages

[Johannes Berg]

On Mon, 2019-09-16 at 11:30 -0400, Michael S. Tsirkin wrote:
> 
> So first we really need to fix up Starting and stopping section,
> explaining that if the FD is invalid, this means ring
> is immediately started, right?

It actually does say that, and ... I even changed it already to say the
ring is also started when receiving the new VHOST_USER_VRING_KICK
message:

   Client must start ring upon receiving a kick (that is, detecting that
   file descriptor is readable) on the descriptor specified by
   ``VHOST_USER_SET_VRING_KICK`` (or receiving the in-band message
   ``VHOST_USER_VRING_KICK`` if negotiated) and stop ring upon receiving
   ``VHOST_USER_GET_VRING_BASE``.


> If we want to keep it simple, my proposal is this, if
> VHOST_USER_PROTOCOL_F_IN_BAND_NOTIFICATIONS is set then
> VHOST_USER_SET_VRING_CALL and VHOST_USER_SET_VRING_KICK are not valid.
> Starting/stopping ring needs to be updated, teaching it
> that ring is started after it gets a kick.

Makes sense, mostly I just need to actually *implement* that.

johannes