test-pmd strange output on AF_XDP

[Alessio Igor Bogani <alessio.bogani@elettra.eu>]

Dear DPDK users,

Sorry for my very bad English.

I'm trying to test DPDK on two systems which are connected to each
other with a cross cable. The first one is a generic Intel x86_64
which uses net_e1000_igb. The second one is an ARMv7 which uses af_xdp
and shows a strange test-pmd output.

Launching test-pmd on the Intel system using:
dpdk-testpmd --no-telemetry --no-huge -l0-1 -n1  --
--port-topology=chained  --forward-mode=txonly  --total-num-mbufs=2048
--stats-period=1 --eth-peer=0,50:51:a9:98:d4:26
produces a reasonable output:
EAL: Detected CPU lcores: 2
EAL: Detected NUMA nodes: 1
EAL: Static memory layout is selected, amount of reserved memory can
be adjusted with -m or --socket-mem
EAL: Detected static linkage of DPDK
EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'VA'
EAL: VFIO support initialized
EAL: Using IOMMU type 1 (Type 1)
EAL: Ignore mapping IO port bar(2)
EAL: Probe PCI driver: net_e1000_igb (8086:157b) device: 0000:01:00.0 (socket 0)
Set txonly packet forwarding mode
testpmd: create a new mbuf pool <mb_pool_0>: n=2048, size=2176, socket=0
testpmd: preferred mempool ops selected: ring_mp_mc
Configuring Port 0 (socket 0)
Port 0: 00:07:32:6F:EF:0D
Checking link statuses...
Done
No commandline core given, start packet forwarding
txonly packet forwarding - ports=1 - cores=1 - streams=1 - NUMA
support enabled, MP allocation mode: native
Logical Core 1 (socket 0) forwards packets on 1 streams:
  RX P=0/Q=0 (socket 0) -> TX P=0/Q=0 (socket 0) peer=50:51:A9:98:D4:26

  txonly packet forwarding packets/burst=32
  packet len=64 - nb packet segments=1
  nb forwarding cores=1 - nb forwarding ports=1
  port 0: RX queue number: 1 Tx queue number: 1
    Rx offloads=0x0 Tx offloads=0x0
    RX queue: 0
      RX desc=512 - RX free threshold=32
      RX threshold registers: pthresh=0 hthresh=0  wthresh=0
      RX Offloads=0x0
    TX queue: 0
      TX desc=512 - TX free threshold=0
      TX threshold registers: pthresh=8 hthresh=1  wthresh=16
      TX offloads=0x0 - TX RS bit threshold=0
  ######################## NIC statistics for port 0  ########################
  RX-packets: 11         RX-missed: 0          RX-bytes:  932
  RX-errors: 0
  RX-nombuf:  0
  TX-packets: 67473342   TX-errors: 0          TX-bytes:  4318294500

  Throughput (since last show)
  Rx-pps:            0          Rx-bps:            0
  Tx-pps:      1420391          Tx-bps:    727240920
  ############################################################################

On the ARMv7 I have launched test-pmd using:
dpdk-testpmd --no-telemetry --no-huge -l0-1 -n1 --vdev
net_af_xdp0,iface=eth0  -- --port-topology=chained
--forward-mode=rxonly --total-num-mbufs=2048 --stats-period=1
--eth-peer=0,00:07:32:6F:EF:0D
producing a strange (for me) output:
EAL: Detected CPU lcores: 2
EAL: Detected NUMA nodes: 1
EAL: Static memory layout is selected, amount of reserved memory can
be adjusted with -m or --socket-mem
EAL: Detected static linkage of DPDK
EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'VA'
Set rxonly packet forwarding mode
testpmd: create a new mbuf pool <mb_pool_0>: n=2048, size=2176, socket=0
testpmd: preferred mempool ops selected: ring_mp_mc
Configuring Port 0 (socket 0)
libbpf: elf: skipping unrecognized data section(7) .xdp_run_config
libbpf: elf: skipping unrecognized data section(8) xdp_metadata
libxdp: XDP flag not supported by libxdp.
libbpf: elf: skipping unrecognized data section(7) xdp_metadata
libbpf: prog 'xdp_dispatcher': BPF program load failed: Invalid argument
libbpf: prog 'xdp_dispatcher': -- BEGIN PROG LOAD LOG --
Validating prog0() func#1...
btf_vmlinux is malformed
Arg#0 type PTR in prog0() is not supported yet.
processed 0 insns (limit 1000000) max_states_per_insn 0 total_states 0
peak_states 0 mark_read 0
-- END PROG LOAD LOG --
libbpf: failed to load program 'xdp_dispatcher'
libbpf: failed to load object '/usr/local/lib/bpf//xdp-dispatcher.o'
libxdp: Failed to load dispatcher: Invalid argument
libxdp: Falling back to loading single prog without dispatcher
Port 0: 50:51:A9:98:D4:26
Checking link statuses...
Done
No commandline core given, start packet forwarding
rxonly packet forwarding - ports=1 - cores=1 - streams=1 - NUMA
support enabled, MP allocation mode: native
Logical Core 1 (socket 0) forwards packets on 1 streams:
  RX P=0/Q=0 (socket 0) -> TX P=0/Q=0 (socket 0) peer=00:07:32:6F:EF:0D

  rxonly packet forwarding packets/burst=32
  nb forwarding cores=1 - nb forwarding ports=1
  port 0: RX queue number: 1 Tx queue number: 1
    Rx offloads=0x0 Tx offloads=0x0
    RX queue: 0
      RX desc=0 - RX free threshold=0
      RX threshold registers: pthresh=0 hthresh=0  wthresh=0
      RX Offloads=0x0
    TX queue: 0
      TX desc=0 - TX free threshold=0
      TX threshold registers: pthresh=0 hthresh=0  wthresh=0
      TX offloads=0x0 - TX RS bit threshold=0
 ######################## NIC statistics for port 0  ########################
  RX-packets: 0          RX-missed: 7363489    RX-bytes:  0
  RX-errors: 0
  RX-nombuf:  0
  TX-packets: 0          TX-errors: 0          TX-bytes:  0

  Throughput (since last show)
  Rx-pps:            0          Rx-bps:            0
  Tx-pps:            0          Tx-bps:            0
  ############################################################################

Is it the output expected? What did I do wrong?

Thanks!

Ciao,
Alessio