On Fri, Sep 5, 2025 at 6:24 AM Paul Chaignon <paul.chaignon@xxxxxxxxx> wrote: > > On Thu, Sep 04, 2025 at 09:27:58AM -0700, Amery Hung wrote: > > > > > > On 9/4/25 9:02 AM, Daniel Borkmann wrote: > > > On 9/4/25 5:56 PM, Alexei Starovoitov wrote: > > > > On Thu, Sep 4, 2025 at 5:11 AM Paul Chaignon > > > > <paul.chaignon@xxxxxxxxx> wrote: > > > > > > > > > > This patch adds support for crafting non-linear skbs in BPF test runs > > > > > for tc programs, via a new flag BPF_F_TEST_SKB_NON_LINEAR. When this > > > > > flag is set, only the L2 header is pulled in the linear area. > > > > > > > > ... > > > > > > > > > + /* eth_type_trans expects the Ethernet header in > > > > > the linear area. */ > > > > > + __pskb_pull_tail(skb, ETH_HLEN); > > > > > > > > Looks useful, but only L2 ? Is it realistic ? > > > > I don't recall any driver that would do L2 only. > > > > Is L2 only enough to cover all corner cases in your progs ? > > > > Should the linear size be a configurable parameter for prog_run() ? > > I think it's enough for Cilium. It's a bit of a worst case for us AFAIU. > In any case, I'm definitely not against making it configurable. > > > > > > > Yeah perhaps we could make this configurable. The ETH_HLEN is a common > > > case > > > we've seen and also what virtual drivers pull in at min, but with NICs > > > doing > > > header/data split its probably better to let the user define this as part > > > of the testing. Then we're more flexible. > > > > > > > How about letting users specify the linear size through ctx->data_end? I am > > working on a set that introduces a kfunc, bpf_xdp_pull_data(). A part of is > > to support non-linear xdp_buff in test_run_xdp, and I am doing it through > > ctx->data_end. Is it something reasonable for test_run_skb? > > Oh, nice! That was next on my list :) > > Why use data_end though? I guess it'd work for skb, but can't we just > add a new field to the anonymous struct for BPF_PROG_TEST_RUN? > I choose to use ctx_in because it doesn't change the interface and feels natural. kattr->test.ctx_in is already copied from users and shows users' expectation about the input ctx. I think we should honor that (as long as the value makes sense). WDYT? Thanks for working on this. It would be great if there is some consistency between test_run_skb and test_run_xdp. > > > > > Cheers, > > > Daniel > >
