static struct rte_eth_conf default_port_conf = {    .rxmode = {        .mq_mode = ETH_MQ_RX_RSS,        .max_rx_pkt_len = ETHER_MAX_LEN,        .split_hdr_size = 0, /**< hdr buf size */        .header_split   = 0, /**< Header Split disabled */        .hw_ip_checksum = 1, /**< IP checksum offload enabled */        .hw_vlan_filter = 0, /**< VLAN filtering disabled */        .hw_vlan_strip  = 0, /**< VLAN strip disabled. */        .hw_vlan_extend = 0, /**< Extended VLAN disabled. */        .jumbo_frame    = 0, /**< Jumbo Frame Support disabled */        .hw_strip_crc   = 0, /**< CRC stripped by hardware */        .enable_lro     = 0, /**< LRO disabled */    },    .rx_adv_conf = {        .rss_conf = {            .rss_key = default_rsskey_40bytes,            .rss_key_len = 40,            .rss_hf = ETH_RSS_PROTO_MASK,        },    },    .txmode = {        .mq_mode = ETH_MQ_TX_NONE,    },};

文档出处：

#define PKT_TX_L4_NO_CKSUM   (0ULL << 52)

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
• set the flag PKT_TX_IPV4 or PKT_TX_IPV6
• calculate the pseudo header checksum and set it in the L4 header (only for TCP or UDP). See  and . For SCTP, set the crc field to 0.Disable L4 cksum of TX pkt.

static uint16_tget_psd_sum(void *l3_hdr, uint64_t ol_flags){	if (ol_flags & PKT_TX_IPV4)		return rte_ipv4_phdr_cksum(l3_hdr, ol_flags);	else /* assume ethertype == ETHER_TYPE_IPv6 */		return rte_ipv6_phdr_cksum(l3_hdr, ol_flags);}

static uint64_tprocess_inner_cksums(struct ether_hdr *eth_hdr, union tunnel_offload_info *info){        void *l3_hdr = NULL;        uint8_t l4_proto;        uint16_t ethertype;        struct ipv4_hdr *ipv4_hdr;        struct ipv6_hdr *ipv6_hdr;        struct udp_hdr *udp_hdr;        struct tcp_hdr *tcp_hdr;        struct sctp_hdr *sctp_hdr;        uint64_t ol_flags = 0;        info->l2_len = sizeof(struct ether_hdr);        ethertype = rte_be_to_cpu_16(eth_hdr->ether_type);        if (ethertype == ETHER_TYPE_VLAN) {                struct vlan_hdr *vlan_hdr = (struct vlan_hdr *)(eth_hdr + 1);                info->l2_len  += sizeof(struct vlan_hdr);                ethertype = rte_be_to_cpu_16(vlan_hdr->eth_proto);        }        l3_hdr = (char *)eth_hdr + info->l2_len;        if (ethertype == ETHER_TYPE_IPv4) {                ipv4_hdr = (struct ipv4_hdr *)l3_hdr;                ipv4_hdr->hdr_checksum = 0;                ol_flags |= PKT_TX_IPV4;                ol_flags |= PKT_TX_IP_CKSUM;                info->l3_len = sizeof(struct ipv4_hdr);                l4_proto = ipv4_hdr->next_proto_id;        } else if (ethertype == ETHER_TYPE_IPv6) {                ipv6_hdr = (struct ipv6_hdr *)l3_hdr;                info->l3_len = sizeof(struct ipv6_hdr);                l4_proto = ipv6_hdr->proto;                ol_flags |= PKT_TX_IPV6;        } else                return 0; /* packet type not supported, nothing to do */        if (l4_proto == IPPROTO_UDP) {                udp_hdr = (struct udp_hdr *)((char *)l3_hdr + info->l3_len);                ol_flags |= PKT_TX_UDP_CKSUM;                udp_hdr->dgram_cksum = get_psd_sum(l3_hdr, ol_flags);        } else if (l4_proto == IPPROTO_TCP) {                tcp_hdr = (struct tcp_hdr *)((char *)l3_hdr + info->l3_len);                ol_flags |= PKT_TX_TCP_CKSUM;                tcp_hdr->cksum = get_psd_sum(l3_hdr, ol_flags);                if (tso_segsz != 0) {                        ol_flags |= PKT_TX_TCP_SEG;                        info->tso_segsz = tso_segsz;                        info->l4_len = sizeof(struct tcp_hdr);                }        } else if (l4_proto == IPPROTO_SCTP) {                sctp_hdr = (struct sctp_hdr *)((char *)l3_hdr + info->l3_len);                sctp_hdr->cksum = 0;                ol_flags |= PKT_TX_SCTP_CKSUM;        }        return ol_flags;}

/* Disable features that are not supported by port's HW */        if (!(dev_info.tx_offload_capa & DEV_TX_OFFLOAD_UDP_CKSUM)) {            dev_info.default_txconf.txq_flags |= ETH_TXQ_FLAGS_NOXSUMUDP;        }        if (!(dev_info.tx_offload_capa & DEV_TX_OFFLOAD_TCP_CKSUM)) {            dev_info.default_txconf.txq_flags |= ETH_TXQ_FLAGS_NOXSUMTCP;        }        if (!(dev_info.tx_offload_capa & DEV_TX_OFFLOAD_SCTP_CKSUM)) {            dev_info.default_txconf.txq_flags |= ETH_TXQ_FLAGS_NOXSUMSCTP;        }        rte_eth_tx_queue_setup(port_id, q, TX_QUEUE_SIZE,                socketid, &dev_info.default_txconf);