As far as I’m right interpreting the output it doesn’t support it regardless what ethtool says. I can’t offload this simple rule to hardware. On the other hand same rule with skip_sw removed works fine (but with resulting not_in_hw flag). I tried other examples from https://lwn.net/Articles/879034/ with same RTNETLINK answers: Not supported success.
root@router:~# tc qdisc del dev eth0 ingress
root@router:~# tc filter show dev eth0 ingress
root@router:~# tc qdisc add dev eth0 ingress
root@router:~# tc filter add dev eth0 protocol ip parent ffff: flower skip_sw ip
_proto sctp dst_port 80 action drop
RTNETLINK answers: Not supported
We have an error talking to the kernel
root@router:~# tc filter show dev eth0 ingress
root@router:~# tc filter add dev eth0 protocol ip parent ffff: flower ip_proto s
ctp dst_port 80 action drop
root@router:~# tc filter show dev eth0 ingress
filter parent ffff: protocol ip pref 49152 flower chain 0
filter parent ffff: protocol ip pref 49152 flower chain 0 handle 0x1
eth_type ipv4
ip_proto sctp
dst_port 80
not_in_hw
action order 1: gact action drop
random type none pass val 0
index 1 ref 1 bind 1
P.S. I’m far from being proficient with TC policies and would be thankful if someone proves me wrong.
Yet another P.S. opkg install kmod-sched-flower is required if someone wants to repeat the experiment.