[PATCH] docs/vhost-user: clarify the semantics of VHOST_USER_SET_VRING_ENABLE

[Daniil Tatianin <d-tatianin@yandex-team.ru>]

Documentation didn't really make it clear that the payload contains any
sort of desired state field, you could only derive that by looking at
the QEMU implementation of this request. Add an extra note to make that
clear.

Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
---
 docs/interop/vhost-user.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
index 137c9f3669d..79690c73b25 100644
--- a/docs/interop/vhost-user.rst
+++ b/docs/interop/vhost-user.rst
@@ -1346,6 +1346,8 @@ Front-end message types
   :reply payload: N/A
 
   Signal the back-end to enable or disable corresponding vring.
+  Note that the ``num`` field contains the target vring state where 0 means
+  disabled, and any other value means enabled.
 
   This request should be sent only when
   ``VHOST_USER_F_PROTOCOL_FEATURES`` has been negotiated.
-- 
2.34.1