--- openflow-2011-10-12-5.h	2015-07-23 09:54:16.736479345 -0700
+++ openflow-2011-10-12-6.h	2015-07-23 09:54:16.744479346 -0700
@@ -176,8 +176,10 @@
 struct ofp_switch_config {
     struct ofp_header header;
     uint16_t flags;             /* OFPC_* flags. */
-    uint16_t miss_send_len;     /* Max bytes of new flow that datapath should
-                                   send to the controller. */
+    uint16_t miss_send_len;     /* Max bytes of new flow that datapath
+                                   should send to the controller. See
+                                   ofp_controller_max_len for valid values.
+                                   */
 };
 OFP_ASSERT(sizeof(struct ofp_switch_config) == 12);