On Mon, Oct 30, 2023 at 3:16 PM Vladimir Oltean [off-list ref] wrote:

Could you please try to revert the effect of commit 339133f6c318 ("net:
dsa: tag_rtl4_a: Drop bit 9 from egress frames") by setting that bit in
the egress tag again? Who knows, maybe it is the bit which tells the
switch to bypass the forwarding process.

I have already tried that, it was one of the first things I tried,
just looking over the git log and looking for usual suspects.

Sadly it has no effect whatsoever, the problem persists :(

Or maybe there is a bit in a
different position which does this. You could try to fill in all bits in
unknown positions, check that there are no regressions with packet sizes
< 1496, and then see if that made any changes to packet sizes >= 1496.
If it did, try to see which bit made the difference.

Hehe now we're talking :D

I did something similar before, I think just switching a different bit
every 10 packets or so and running a persistent ping until it succeeds
or not.

I'll see what I can come up with.

Yours,
Linus Walleij