diff --git a/xen/include/public/io/netif.h b/xen/include/public/io/netif.h
index 2454448baa..9fcf91a2fe 100644
--- a/xen/include/public/io/netif.h
+++ b/xen/include/public/io/netif.h
@@ -171,7 +171,7 @@
  * The ability of the backend to use a control ring is advertised by
  * setting:
  *
- * /local/domain/X/backend/<domid>/<vif>/feature-ctrl-ring = "1"
+ * /local/domain/X/backend/vif/<domid>/<vif>/feature-ctrl-ring = "1"
  *
  * The frontend provides a control ring to the backend by setting:
  *
@@ -190,6 +190,20 @@
  * order as requests.
  */
 
+/*
+ * Link state
+ * ==========
+ *
+ * The backend can advertise its current link (carrier) state to the
+ * frontend using the /local/domain/X/backend/vif/<domid>/<vif>/carrier
+ * node. If this node is not present, then the frontend should assume that
+ * the link is up (for compatibility with backends that do not implement
+ * this feature). If this node is present, then a value of "0" should be
+ * interpreted by the frontend as the link being down (no carrier) and a
+ * value of "1" should be interpreted as the link being up (carrier
+ * present).
+ */
+
 /*
  * Hash types
  * ==========