I have found and fixed the reason for the first packet going missing;
it is due to 'reverse path filtering', and this can be turned off with
for device in /proc/sys/net/ipv4/conf/*
do
echo 0 >${device}/rp_filter
done
in the test case run script. So
https://github.com/tjcw/bpf-examples/tree/tjcw-integration-0.3/AF_XDP-filter
is ready for review and integration.
Chris Ward, IBM
