On Tue, 3 Mar 2020 20:46:55 +0100 Daniel Borkmann wrote:

Thus, when the data/data_end test fails in generic XDP, the user can
call e.g. bpf_xdp_pull_data(xdp, 64) to make sure we pull in as much as
is needed w/o full linearization and once done the data/data_end can be
repeated to proceed. Native XDP will leave xdp->rxq->skb as NULL, but
later we could perhaps reuse the same bpf_xdp_pull_data() helper for
native with skb-less backing. Thoughts?

I'm curious why we consider a xdpgeneric-only addition. Is attaching 
a cls_bpf program noticeably slower than xdpgeneric?