On Tue, Jan 03, 2023 at 05:21:53PM -0800, Jakub Kicinski wrote: > On Tue, 03 Jan 2023 16:19:49 +0100 Toke Høiland-Jørgensen wrote: > > Hmm, good question! I don't think we've ever explicitly documented any > > assumptions one way or the other. My own mental model has certainly > > always assumed the first frag would continue to be the same size as in > > non-multi-buf packets. > > Interesting! :) My mental model was closer to GRO by frags > so the linear part would have no data, just headers. As I mentioned in my mail just a few mins ago, I think this would be a good model to consider. All headers (including potentially tunnel headers) could be in the linear area with the actual packet data in frags. > A random datapoint is that bpf_xdp_adjust_head() seems > to enforce that there is at least ETH_HLEN.
