Did you test this?

@PeterKietzmann I've tested with tests/lwip. I can send UDP frames from one instance to another on native.

Ah ok. Yes, native works here as well. On samr21-xpro I get the following assertion which might be unrelated.

main(): This is RIOT! (Version: 2018.07-devel-867-ge7deb-515b9e49740c-HEAD)
RIOT lwip test application
Assertion "increment_magnitude <= p->len" failed at /data/riotbuild/riotproject/tests/lwip/bin/pkg/samr21-xpro/lwip/src/core/pbuf.c:583
#! exit 1: powering off

Let's investigate that for a bit then...

@PeterKietzmann I'm unable to reproduce that on IoT-lab so far. Do you have more information on how to reproduce this?

I'm on your branch an flashed tests/lwip to one samr21-xpro board. Some seconds after startup the above mentioned assertion triggers

BTW: same on master...

Still nothing on my IoT-lab nodes. I would find it very strange if practically changing nothing causes assertion failures in the lwip packet buffer.

BTW: same on master...

It doesn't relate to your change. The same error persists on current master, without this PR. So we could theoretically merge this one. On the iotlab (with M3 node) I don't get the assertion either. Did you try the samr21-xpro in saclay?

Did you try the samr21-xpro in saclay?

Yes, node number 1 and 2 :)

Can you try to build in Docker and submit an other exp on samr nodes?

@PeterKietzmann Done, still nothing, works perfectly fine on this side 😢

Well, obviously this is not an issue with your PR. Seems more toolchain related. Will open an issue :/

#9573