- b->mbuf.pkt.data_len = v; /* Current seg length. */
- b->mbuf.pkt.pkt_len = v; /* Total length of all segments linked to
- * this segment. */
+ /* netdev-dpdk does not currently support segmentation; consequently, for
+ * all intents and purposes, 'data_len' (16 bit) and 'pkt_len' (32 bit) may
+ * be used interchangably.
+ *
+ * On the datapath, it is expected that the size of packets
+ * (and thus 'v') will always be <= UINT16_MAX; this means that there is no
+ * loss of accuracy in assigning 'v' to 'data_len'.
+ *
+ * However, control ofpbufs may well be larger than UINT16_MAX (i.e. 'v' >
+ * UINT16_MAX); even though the value is truncated when assigned to
+ * 'data_len', loss of accuracy is avoided in this situation by using
+ * 'pkt_len' to represent the packet size.
+ */
+ b->mbuf.data_len = (uint16_t)v; /* Current seg length. */
+ b->mbuf.pkt_len = v; /* Total length of all segments linked to
+ * this segment. */
+