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. Regards, Masashi Honma.
