NIC is unavailable in DPDK application

Question

I'm studying DPDK and trying to create a simple application, however it can't see a NIC bound to DPDK.

1. Here is a list of network devices I have on my machine

$ dpdk-devbind.py --status-dev net

Network devices using kernel driver
===================================
0000:01:00.0 'RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller 8168' if=enp1s0 drv=r8169 unused=vfio-pci *Active*
0000:02:00.0 'RTL8822BE 802.11a/b/g/n/ac WiFi adapter b822' if=wlp2s0 drv=rtw_8822be unused=rtw88_8822be,vfio-pci *Active*

2. I disable my ethernet NIC (it can't be bound to DPDK while it is active) and bind it to vfio-pci driver successfully

$ ip link set enp1s0 down
$ dpdk-devbind.py -b vfio-pci enp1s0

3. Now dpdk-devbind.py shows that the NIC is using DPDK-compatible driver

$ dpdk-devbind.py --status-dev net

Network devices using DPDK-compatible driver
============================================
0000:01:00.0 'RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller 8168' drv=vfio-pci unused=r8169

Network devices using kernel driver
===================================
0000:02:00.0 'RTL8822BE 802.11a/b/g/n/ac WiFi adapter b822' if=wlp2s0 drv=rtw_8822be unused=rtw88_8822be,vfio-pci *Active*

4. However when I run any example DPDK application it says that there are no available NIC ports. For instance I wrote a simple application

int main(int argc, char *argv[])
{
    int ret;
    int total_ports, avail_ports;

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

    total_ports = rte_eth_dev_count_total();
    avail_ports = rte_eth_dev_count_avail();
    printf("ETH PORTS %d %d\n", total_ports, avail_ports);

    rte_eal_cleanup();

    return 0;
}

and both rte_eth_dev_count_total() and rte_eth_dev_count_avail() return 0.

What am I doing wrong?

Answer 1

The main reason why DPDK ports are not identified in your environment is because the NIC in use is not having a supported vendor Poll Mode Driver. Please refer to list of supported NIC from various vendor Realtek is not among them.

Work around: you can use PCAP PMD to solve the problem. Please follow the steps for your environment as

1. ensure your ethernet port is linked to kernel driver r8169
2. isntall libpacp-dev for your enviorment (linux/bsd)
3. rebuild dpdk with PCAP support.
4. start your application with following args --no-pci --vdev=net_pcap0,iface=enp1s0

This will use libpcap PMD as wrapper for RX and TX over non supported NIC