doc: Fix description of max_len for controller action.

From: Antonin Bas <[email protected]>

Since Open vSwitch 2.7, the max_len option has no effect, and the full
packet is always sent to controllers. This was confirmed with both the
kernel and netdev datapaths.

Reported-by: Antonin Bas <[email protected]>
Reported-at: openvswitch/ovs-issues#295
Acked-by: Simon Horman <[email protected]>
Signed-off-by: Antonin Bas <[email protected]>
Signed-off-by: Ilya Maximets <[email protected]>

Documentation/ref/ovs-actions.7.rst

@@ -694,7 +694,8 @@ encapsulated in an OpenFlow ``packet-in`` message.  The supported options are:
     Limit to *max_len* the number of bytes of the packet to send in the
     ``packet-in.``  A *max_len* of 0 prevents any of the packet from being
     sent (thus, only metadata is included).  By default, the entire packet is
-    sent, equivalent to a *max_len* of 65535.
+    sent, equivalent to a *max_len* of 65535.  This option has no effect in
+    Open vSwith 2.7 and later: the entire packet will always be sent.
 
   ``reason=``\ *reason*
     Specify *reason* as the reason for sending the message in the
@@ -733,6 +734,12 @@ encapsulated in an OpenFlow ``packet-in`` message.  The supported options are:
   options require the Open vSwitch ``NXAST_CONTROLLER`` extension action added
   in Open vSwitch 1.6.
 
+  Open vSwitch 2.7 and later is configured to not buffer packets for the
+  packet-in event.  As a result, the full packet is always sent to
+  controllers.  This means that the ``max_len`` option has no effect on the
+  ``controller`` action, and all values (even 0) are equivalent to the default
+  value of 65535.
+
 
 The ``enqueue`` action
 ----------------------