On 2026/7/5 10:11, Masashi Honma wrote: > 2026年7月4日(土) 22:28 Leon Hwang <[email protected]>: >> Probably, you can get the 'extack->_msg' by tracing dev_xdp_attach using >> kprobe+kretprobe or kprobe.session, if the extack is not NULL. > > Thanks, that's a nice pointer -- dev_xdp_attach() has both the net_device > (so the ifindex, which lets us correlate a failure to a specific attach) > and the extack, and it avoids depending on the tracepoint you want to > retire. > > The tradeoff is that dev_xdp_attach() is a static internal function, so a > probe on it can break across kernels (inlining/signature changes). For a > best-effort error message that's tolerable with a graceful fallback, but > it's a maintenance cost on our side. > > Since this is ultimately just an error-message improvement, and your > in-band BPF_LINK_CREATE work would solve it cleanly for all link types, I > think we'd lean toward waiting for that rather than adding an internal > kprobe to Cilium. Do you have a rough timeline for the BPF_LINK_CREATE > series? That would help us decide whether a stopgap is worth it.
I will post the RFC around October. Thanks, Leon
