Implementing a simple TAP PMD to dpdk-vhost structure

[David Marchand]

Hello Ken,

On Wed, Sep 6, 2023 at 3:56 AM Nicolson Ken (ニコルソン ケン)
<ken.nicolson at jp.panasonic.com> wrote:
>
> Hi all,
>
> Using dpdk 22.11.2 on Ubuntu 22.04
>
> I have a really simple use case, but I cannot find how to implement it. I've set up QEMU with all the required virtio support, so I just need to configure my Host OS-side. I want to send data from a PCAP file via tcpreplay from the Host to the Guest, so I use this command line:
>
> $ sudo /home/integ/dpdk-stable-22.11.2/build/examples/dpdk-vhost -l 0-3 -n 4 --socket-mem 1024 --vdev 'net_tap0' -- --socket-file /tmp/sock0 --client -p 1
>
> However, this fails with:
>
> EAL: Detected CPU lcores: 20
> EAL: Detected NUMA nodes: 1
> EAL: Detected static linkage of DPDK
> EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
> EAL: Selected IOVA mode 'PA'
> VHOST_PORT: Failed to get VMDq info.
> EAL: Error - exiting with code: 1
>   Cause: Cannot initialize network ports
>
> The offending code is from examples/vhost/main.c:
>
>         if (dev_info.max_vmdq_pools == 0) {
>                 RTE_LOG(ERR, VHOST_PORT, "Failed to get VMDq info.\n");
>                 return -1;
>         }
>
> This is because the TAP PMD doesn't support VMDq pools.
>
> Is there an easy way to get this to work?

This sounds strange to require VMDq support...
Copying Maxime and Chenbo who probably know better about this example code.

Alternatively, did you consider using testpmd with the vhost pmd instead ?


-- 
David Marchand