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specs/vhost-user: fix spec to match reality 

We wanted to start/stop rings on VRING_ENABLE, but that is not what QEMU
does. Rather than tweaking code some more, with risk to stability, let's
just document it as it is.

We'll be  able to fix this in the future with a new protocol feature bit.

Reported-by: Victor Kaplansky <victork@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2015-11-17 13:55:48 +02:00
parent 5c93c47338
commit 7ebcfe5692
1 changed files with 17 additions and 11 deletions
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28
docs/specs/vhost-user.txt
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@ -148,20 +148,26 @@ 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.
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
VHOST_USER_SET_VRING_ENABLE with parameter 1, or after it has been disabled by
VHOST_USER_SET_VRING_ENABLE with parameter 0.
Each ring is initialized in a stopped state, client must not process it until
ring is enabled.
ring is started, or after it has been stopped.
If VHOST_USER_F_PROTOCOL_FEATURES has been negotiated, client must start and
stop ring processing upon receiving VHOST_USER_SET_VRING_ENABLE with parameters
1 and 0 respoectively.
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, and stop ring upon receiving
VHOST_USER_GET_VRING_BASE.
If VHOST_USER_F_PROTOCOL_FEATURES has not been negotiated, client must start
ring processing upon receiving a kick (that is, detecting that file descriptor
is readable) on the descriptor specified by VHOST_USER_SET_VRING_KICK, and stop
ring processing upon receiving VHOST_USER_GET_VRING_BASE.
While rings are running, client must support changing some configuration
aspects on the fly.
While processing the rings (when they are started and enabled), client must
support changing some configuration aspects on the fly.
Multiple queue support
----------------------