can you show me the codes of the l2 forwarding by DPDK

是的，我可以为您提供 DPDK 实现 L2 转发的代码示例。以下是一份使用 DPDK 实现 L2 转发的代码：

#include <stdio.h>
#include <stdint.h>
#include <rte_eal.h>
#include <rte_ethdev.h>
#include <rte_mbuf.h>

#define NUM_MBUFS 8191
#define MBUF_CACHE_SIZE 250
#define BURST_SIZE 32

static const struct rte_eth_conf port_conf_default = {
    .rxmode = {
        .max_rx_pkt_len = ETHER_MAX_LEN,
    },
};

int main(int argc, char *argv[]) {
    int ret;
    uint16_t nb_ports;
    uint16_t portid;
    struct rte_mbuf *pkts_burst[BURST_SIZE];
    unsigned i, j;

    ret = rte_eal_init(argc, argv);
    if (ret < 0)
        rte_exit(EXIT_FAILURE, "Invalid EAL parameters\n");

    nb_ports = rte_eth_dev_count();
    if (nb_ports == 0)
        rte_exit(EXIT_FAILURE, "No Ethernet ports\n");

    for (i = 0; i < nb_ports; i++) {
        portid = i;
        ret = rte_eth_dev_configure(portid, 1, 1, &port_conf_default);
        if (ret < 0)
            rte_exit(EXIT_FAILURE, "Cannot configure device: err=%d, port=%u\n",
                     ret, portid);

        ret = rte_eth_dev_start(portid);
        if (ret < 0)
            rte_exit(EXIT_FAILURE, "Cannot start device: err=%d, port=%u\n",
                     ret, portid);

        rte_eth_promiscuous_enable(portid);
    }

    while (1) {
        for (i = 0; i < nb_ports; i++) {
            portid = i;
            const uint16_t nb_rx = rte_eth_rx_burst(portid, 0,
                                                    pkts_burst, BURST_SIZE);

            if (unlikely(nb_rx == 0))
                continue;

            for (j = 0; j < nb_rx; j++) {
                struct rte_mbuf *m = pkts_burst[j];
                rte_eth_tx_burst(portid ^ 1, 0, &m, 1);
                rte_pktmbuf_free(m);
            }
        }
    }

    return 0;
}

请注意，这仅仅