rte_pktmbuf_chain

    m = rte_pktmbuf_alloc(mpool);
    rte_pktmbuf_append(m, 1000);
    mbuf_dump(m);

    m2 = rte_pktmbuf_alloc(mpool);
    rte_pktmbuf_append(m2, 500);
    mbuf_dump(m2);

    rte_pktmbuf_chain(m, m2);
    printf("after m  rte_pktmbuf_chain \n");
    mbuf_dump(m);

RTE_PKTMBUF_HEADROOM: 128
sizeof(mbuf): 128
m: 0x13f919c00
m->refcnt: 1
m->buf_addr: 0x13f919c90
m->data_off: 128
m->buf_len: 1646
m->pkt_len: 1000
m->data_len: 1000
m->nb_segs: 1
m->next: (nil)
m->buf_addr+m->data_off: 0x13f919d10
rte_pktmbuf_mtod(m): 0x13f919d10
rte_pktmbuf_data_len(m): 1000
rte_pktmbuf_pkt_len(m): 1000
rte_pktmbuf_headroom(m): 128
rte_pktmbuf_tailroom(m): 518
rte_pktmbuf_data_room_size(mpool): 1646
rte_pktmbuf_priv_size(mpool): 16

RTE_PKTMBUF_HEADROOM: 128
sizeof(mbuf): 128
m: 0x13f919480
m->refcnt: 1
m->buf_addr: 0x13f919510
m->data_off: 128
m->buf_len: 1646
m->pkt_len: 500
m->data_len: 500
m->nb_segs: 1
m->next: (nil)
m->buf_addr+m->data_off: 0x13f919590
rte_pktmbuf_mtod(m): 0x13f919590
rte_pktmbuf_data_len(m): 500
rte_pktmbuf_pkt_len(m): 500
rte_pktmbuf_headroom(m): 128
rte_pktmbuf_tailroom(m): 1018
rte_pktmbuf_data_room_size(mpool): 1646
rte_pktmbuf_priv_size(mpool): 16

================== after m  rte_pktmbuf_chain ===================== 
RTE_PKTMBUF_HEADROOM: 128
sizeof(mbuf): 128
m: 0x13f919c00
m->refcnt: 1
m->buf_addr: 0x13f919c90
m->data_off: 128
m->buf_len: 1646
m->pkt_len: 1500
m->data_len: 1000
m->nb_segs: 2
m->next: 0x13f919480
m->buf_addr+m->data_off: 0x13f919d10
rte_pktmbuf_mtod(m): 0x13f919d10
rte_pktmbuf_data_len(m): 1000
rte_pktmbuf_pkt_len(m): 1500
rte_pktmbuf_headroom(m): 128
rte_pktmbuf_tailroom(m): 518
rte_pktmbuf_data_room_size(mpool): 1646
rte_pktmbuf_priv_size(mpool): 16