On Mon, Nov 23, 2015 at 12:54:56PM +0200, Michael S. Tsirkin wrote:
> It seems that we currently have some duplication between
> started and enabled states.
>
> The actual reason is that enable is not documented correctly:
> what it does is connecting ring to the backend.
>
> This is important for MQ, because a Linux guest expects TX
> packets to be completed even if it disables some queues
> temporarily.
Thanks for the clarification. And
Reviewed-by: Yuanhan Liu <yuanhan....@linux.intel.com>
--yliu
>
> Cc: Yuanhan Liu <yuanhan....@linux.intel.com>
> Cc: Victor Kaplansky <vict...@redhat.com>
> Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
> ---
> docs/specs/vhost-user.txt | 20 +++++++++++++++-----
> 1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
> index 7b9cd6d..0312d40 100644
> --- a/docs/specs/vhost-user.txt
> +++ b/docs/specs/vhost-user.txt
> @@ -148,13 +148,23 @@ a feature bit was dedicated for this purpose:
>
> Starting and stopping rings
> ----------------------
> -Client must only process each ring when it is both started and enabled.
> +Client must only process each ring when it is started.
> +
> +Client must only pass data between the ring and the
> +backend, when the ring is enabled.
> +
> +If ring is started but disabled, client must process the
> +ring without talking to the backend.
> +
> +For example, for a networking device, in the disabled state
> +client must not supply any new RX packets, but must process
> +and discard any TX packets.
>
> If VHOST_USER_F_PROTOCOL_FEATURES has not been negotiated, the ring is
> initialized
> in an enabled state.
>
> If VHOST_USER_F_PROTOCOL_FEATURES has been negotiated, the ring is
> initialized
> -in a disabled state. Client must not process it until ring is enabled by
> +in a disabled state. Client must not pass data to/from the backend until
> ring is enabled by
> VHOST_USER_SET_VRING_ENABLE with parameter 1, or after it has been disabled
> by
> VHOST_USER_SET_VRING_ENABLE with parameter 0.
>
> @@ -166,7 +176,7 @@ descriptor is readable) on the descriptor specified by
> VHOST_USER_SET_VRING_KICK, and stop ring upon receiving
> VHOST_USER_GET_VRING_BASE.
>
> -While processing the rings (when they are started and enabled), client must
> +While processing the rings (whether they are enabled or not), client must
> support changing some configuration aspects on the fly.
>
> Multiple queue support
> @@ -309,11 +319,11 @@ Message types
> Id: 4
> Master payload: N/A
>
> - This is no longer used. Used to be sent to request stopping
> + This is no longer used. Used to be sent to request disabling
> all rings, but some clients interpreted it to also discard
> connection state (this interpretation would lead to bugs).
> It is recommended that clients either ignore this message,
> - or use it to stop all rings.
> + or use it to disable all rings.
>
> * VHOST_USER_SET_MEM_TABLE
>
> --
> MST
