- * When doing Tx offload like TSO or checksum, the HW needs to configure the
- * tunnel type into the HW descriptors.
+ * The tunnel type must be specified for TSO or checksum on the inner part
+ * of tunnel packets.
+ * These flags can be used with PKT_TX_TCP_SEG for TSO, or PKT_TX_xxx_CKSUM.
+ * The mbuf fields for inner and outer header lengths are required:
+ * outer_l2_len, outer_l3_len, l2_len, l3_len, l4_len and tso_segsz for TSO.