MLX5 VF stops transmitting when the Physical Function is added to a Linux bridge

[Stephen Hemminger]

On Mon, 25 Mar 2024 15:59:36 +0100
Antonio Di Bacco <a.dibacco.ks at gmail.com> wrote:

> I have a Connect X5 card (PF ens1f0np0) directly connected to another server:
> 
> 1) create VF on PF on both servers
> 2) change mac address of VFs to my own addressing
> 3) start testpmd on server 1 in txonly mode to transmit to server 0
> 4) start testpmd on server 0 in rxonly mode to receive
> 5) everything is fine, I keep receiving packets on node-0
> 
> Now, on server 1 I add the PF to a linux bridge, and everything's still fine.
> 
> If I add another interface (a simple 1Gbps with no VF, ens5f0)  to the
> linux bridge, then, I don't receive anymore packets on node-0
> 
> If I remove the ens5f0 from the bridge or I put down the ens5f0 the
> traffic flow restarts.
> 
> I understand that DPDK uses the VF directly with no dependencies on
> the kernel. How can operations on the kernel side (like adding an
> interface to bridge) can affect the VF?
> 
> 
> Best regards,
> Antonio.

Mellanox is bifurcated driver, so kernel and DPDK interact.
Adding device to bridge will change MAC address.