[dpdk-dev,v3,04/13] mbuf: add help about TX checksum flags
Commit Message
Describe how to use hardware checksum API.
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
---
lib/librte_mbuf/rte_mbuf.h | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
@@ -98,14 +98,17 @@ extern "C" {
/* add new TX flags here */
#define PKT_TX_VXLAN_CKSUM (1ULL << 50) /**< TX checksum of VXLAN computed by NIC */
#define PKT_TX_IEEE1588_TMST (1ULL << 51) /**< TX IEEE1588 packet to timestamp. */
-/*
- * Bits 52+53 used for L4 packet type with checksum enabled.
- * 00: Reserved
- * 01: TCP checksum
- * 10: SCTP checksum
- * 11: UDP checksum
+
+/**
+ * Bits 52+53 used for L4 packet type with checksum enabled: 00: Reserved,
+ * 01: TCP checksum, 10: SCTP checksum, 11: UDP checksum. To use hardware
+ * L4 checksum offload, the user needs to:
+ * - fill l2_len and l3_len in mbuf
+ * - set the flags PKT_TX_TCP_CKSUM, PKT_TX_SCTP_CKSUM or PKT_TX_UDP_CKSUM
+ * - calculate the pseudo header checksum and set it in the L4 header (only
+ * for TCP or UDP). For SCTP, set the crc field to 0.
*/
-#define PKT_TX_L4_NO_CKSUM (0ULL << 52) /**< Disable L4 cksum of TX pkt. */
+#define PKT_TX_L4_NO_CKSUM (0ULL << 52) /* Disable L4 cksum of TX pkt. */
#define PKT_TX_TCP_CKSUM (1ULL << 52) /**< TCP cksum of TX pkt. computed by NIC. */
#define PKT_TX_SCTP_CKSUM (2ULL << 52) /**< SCTP cksum of TX pkt. computed by NIC. */
#define PKT_TX_UDP_CKSUM (3ULL << 52) /**< UDP cksum of TX pkt. computed by NIC. */