[dpdk-users] Attatching global memory pointer to mbuf and sending it to ethernet port.

[JeongHwan Kim <kjh.kernel.kr@gmail.com>]

Hi, everyone

I'd like to send the contents of global memory through ethernet port
without memory copying to mbuf.
So, I attached the pointer of global memory to mbuf's buffer address, but
segfault occurs when I send it to ethernet port.
I 'm using dpdk version 2019.11  and eal config with   "--iova-mode=pa"
option.
My hw platform is NXP ls2088a.

My routine is like this:

int buf_len = 100;
struct rte_mbuf *m = rte_pktmbuf_alloc(mbuf_pool);
struct rte_mbuf_ext_shared_info *shinfo =
rte_pktmbuf_ext_shinfo_init_helper(buf_addr, &buf_len,  free_cb, fcb_arg);
rte_pktmbuf_attach_extbuf(m, buf_addr, buf_iova, buf_len, shinfo);
rte_pktmbuf_reset_headroom(m);
...
and sent  "m"  to ethernet, the result was

Thread 4 "lcore-slave-1" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0xffffbdb0c910 (LWP 10614)]
0x0000aaaaaab73f58 in eth_mbuf_to_sg_fd ()

The buffer was created as follows :
user_mz = rte_memzone_reserve_aligned("user_mz", size, rte_socket_id(),
                    RTE_MEMZONE_1GB|RTE_MEMZONE_IOVA_CONTIG,
                    RTE_CACHE_LINE_SIZE);
buf_addr = user_mz->addr;
buf_iova = user_mz->iova;

Please give me a hint for this problem.
Thanks in advance.

Jeong-Hwa Kim.