On Sat, Feb 14, 2026 at 09:19:49AM -0800, Dimitri Daskalakis wrote:
> Increasing the MTU beyond the HDS threshold causes the hardware to
> fragment packets across multiple buffers. If a single-buffer XDP program
> is attached, the driver will drop all multi-frag frames. While we can't
> prevent a remote sender from sending non-TCP packets larger than the MTU,
> this will prevent users from inadvertently breaking new TCP streams.
>
> Traditionally, drivers supported XDP with MTU less than 4Kb
> (packet per page). Fbnic currently prevents attaching XDP when MTU is too
> high.
> But it does not prevent increasing MTU after XDP is attached.
>
> Fixes: 1b0a3950dbd4 ("eth: fbnic: Add XDP pass, drop, abort support")
> Signed-off-by: Jakub Kicinski <[email protected]>
> Signed-off-by: Dimitri Daskalakis <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
