- * with 'struct odp_msg' as a header. Only messages of the types selected
- * with the set_listen_mask member function should be received.
+ * with 'struct odp_msg' as a header, and must have at least
+ * DPIF_RECV_MSG_PADDING bytes of headroom (allocated using
+ * e.g. ofpbuf_reserve()). Only messages of the types selected with the
+ * set_listen_mask member function should be received.