Am 25.02.25 um 19:23 schrieb Willem de Bruijn:
Marcus Wichelmann wrote:
Am 24.02.25 um 16:29 schrieb Marcus Wichelmann:
[...]
+ /* By default, Linux sends IPv6 multicast listener reports which
+ * interfere with this test. Set the IFF_NOARP flag to ensure
+ * silence on the interface.
+ */
+ SYS(close, "ip link set dev " RX_NAME " arp off");
SYS(close, "ip link set dev " RX_NAME " up");
Hm, setting the NOARP flag seems to have not been sufficient to fix the flaky
test:
https://github.com/kernel-patches/bpf/actions/runs/13507111620/job/37739614229
I was not able to reproduce it locally or with my own CI runs unfortunately, but
I'll try something else in the next patch version which should definitely stop
IPv6 multicast listener report packets from messing with the tests.
You probably want to pass nodad to any ip -6 addr add.
This is a common option you'll find in tools/testing/selftests/net.
RFC 3810 section 5.2.13 says
"
For stateless autoconfiguration, as defined in [RFC2462], a node is
required to join several IPv6 multicast groups, in order to perform
Duplicate Address Detection (DAD).
"
I'm not explicitly adding an IPv6 address, but this rather comes from the IPv6
link-local address being automatically assigned.
This can be avoided by setting addrgenmode=none, either using "ip link" or by
setting the corresponding sysctl.
But I think I'll add a filter for all non test related packets to the XDP program
instead.
I like this solution more, as it should be easier to grasp, very reliable and also
solves this for all tests in just one place.
Thanks!
