Re: [PATCH net-next] net/mlx5: Add MLX5_VXLAN config option

[Marc Harvey]

On Wed, Apr 29, 2026 at 7:01 PM Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
>
> Are you aware of NETIF_F_RX_UDP_TUNNEL_PORT ?
> I haven't checked it does exactly what we need, but I recall there was
> a ethtool feature for this..

Thanks, I didn't know about that feature and mlx5 uses it. However,
mlx5 unconditionally sets the `UDP_TUNNEL_NIC_INFO_STATIC_IANA_VXLAN`
flag, which excludes port 4789 from the entire UDP tunnel core offload
management (see `__udp_tunnel_nic_add_port()`).

So using ethtool to disable `NETIF_F_RX_UDP_TUNNEL_PORT` will not
disable vxlan offload for port 4789.

I think a better approach would be to just remove this static
automatic offloading for port 4789, mlx5 is the only driver using
`UDP_TUNNEL_NIC_INFO_STATIC_IANA_VXLAN` anyway. However, there might
be a reason for this, such as some supported hardware offloading vxlan
on port 4789 by default even without commands from the driver.

If mlx5 continues to use the `UDP_TUNNEL_NIC_INFO_STATIC_IANA_VXLAN`
flag, then some change is required to fully disable vxlan offloading.