DPDK with AF_XDP: Failed to create xsk socket - linux

Question

I am trying to run AF_XDP poll mode driver. Kernel Version is 5.4(CONFIG_XDP_SOCKETS=y).
When i run the samples provided by DPDK website, an error was happened.
root#n211-203-164:~# dpdk-testpmd --vdev=net_af_xdp0,iface=eth3 -- -i --total-num-mbufs=10240
EAL: Detected 96 lcore(s)
EAL: Detected 2 NUMA nodes
EAL: Detected static linkage of DPDK
EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
EAL: Selected IOVA mode 'PA'
EAL: No available 1048576 kB hugepages reported
EAL: VFIO support initialized
EAL: Probe PCI driver: mlx5_pci (15b3:1017) device: 0000:5e:00.0 (socket 0)
mlx5_net: Default miss action is not supported.
EAL: Probe PCI driver: mlx5_pci (15b3:1017) device: 0000:5e:00.1 (socket 0)
mlx5_net: Default miss action is not supported.
EAL: Probe PCI driver: mlx5_pci (15b3:1017) device: 0000:86:00.0 (socket 1)
mlx5_net: Default miss action is not supported.
EAL: Probe PCI driver: mlx5_pci (15b3:1017) device: 0000:86:00.1 (socket 1)
mlx5_net: Default miss action is not supported.
Interactive-mode selected
testpmd: create a new mbuf pool <mb_pool_0>: n=10240, size=2176, socket=0
testpmd: preferred mempool ops selected: ring_mp_mc
testpmd: create a new mbuf pool <mb_pool_1>: n=10240, size=2176, socket=1
testpmd: preferred mempool ops selected: ring_mp_mc
Warning! port-topology=paired and odd forward ports number, the last port will pair with itself.
Configuring Port 0 (socket 0)
Port 0: B8:CE:F6:35:DB:3A
Configuring Port 1 (socket 0)
Port 1: B8:CE:F6:35:DB:3B
Configuring Port 2 (socket 1)
Port 2: B8:CE:F6:3B:31:4A
Configuring Port 3 (socket 1)
Port 3: B8:CE:F6:3B:31:4B
Configuring Port 4 (socket 0)
xsk_configure(): Failed to create xsk socket.
eth_rx_queue_setup(): Failed to configure xdp socket
Fail to configure port 4 rx queues
EAL: Error - exiting with code: 1
Cause: Start ports failed
it seems that XSK socket call bind() failed and eth_rx_queue_setup() failed as a result.
How to correctly configure EAL parameters to run dpdk-testpmd with vdev=af_net_xdp0? Any help is greatly appreciated.

Answer 1

It is an issue about rlimit. I wrote a simple test programer.
#include <bpf.h>
#include <xsk.h>
#include <stdio.h>
//#include <sys/resource.h>
//static struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
int main() {
//setrlimit(RLIMIT_MEMLOCK, & r);
int fd = bpf_create_map_name(BPF_MAP_TYPE_XSKMAP, "xsks_map", sizeof(int), sizeof(int), 1, 0);
printf("fd:%d\n", fd);
return 0;
}
Execute cmd strace -e bpf ./test-prog and the result could be like this:
root#n211-203-164:~# strace -e bpf ./test
bpf(BPF_MAP_CREATE, {map_type=0x11 /* BPF_MAP_TYPE_??? */, key_size=4, value_size=4, max_entries=1}, 112) = -1 EPERM (Operation not permitted)
fd:-1 1
+++ exited with 0 +++
This means max locked memory caused the insufficient resource allocation.
Execute cmd ulimit -a could find max locked memory is 64 kbytes.
There are 2 solutions, one is to enlarge max locked memory globally by executing cmd ulimit -S -l <a big value>, and the other is to call setrlimit() into libbpf.so when creating a BPF map.