Em Wed, Jun 16, 2021 at 03:36:54PM -0700, Andrii Nakryiko escreveu: > On Wed, Jun 16, 2021 at 1:41 PM Arnaldo Carvalho de Melo <arnaldo.melo@xxxxxxxxx> wrote: > > And if I use pahole's BTF loader I find the info about that function: > > > > [acme@seventh linux]$ strace -e openat -o /tmp/bla pfunct -F btf tcp_cong_avoid_ai ; grep vmlinux /tmp/bla > > void tcp_cong_avoid_ai(struct tcp_sock * tp, u32 w, u32 acked); > > openat(AT_FDCWD, "/sys/kernel/btf/vmlinux", O_RDONLY) = 3 > > > > So this should be unrelated to the breakage you noticed in the CI. > > > > I'm trying to to reproduce the CI breakage by building the kernel and > > running selftests after a reboot. > > > > I suspect I'm missing something, can you see what it is? > > Oh, I didn't realize initially what it is. This is not kernel-related, > you are right. You just need newer Clang. Can you please use nightly > version or build from sources? Basically, your Clang is too old and it > doesn't generate BTF information for extern functions in BPF code. Oh well, I thought that that clang was new enough, the system being Fedora rawhide: [acme@seventh ~]$ clang -v |& head -1 clang version 12.0.0 (https://github.com/llvm/llvm-project 87369c626114ae17f4c637635c119e6de0856a9a) I'm now building the single-repo main... Would you consider a patch for libbpf that would turn this: > > > libbpf: failed to find BTF for extern 'tcp_cong_avoid_ai' [27] section: -2 > > > Error: failed to open BPF object file: No such file or directory > > > make: *** [Makefile:460: /mnt/linux/tools/testing/selftests/bpf/bpf_cubic.skel.h] Error 255 > > > make: *** Deleting file '/mnt/linux/tools/testing/selftests/bpf/bpf_cubic.skel.h' > > > make: Leaving directory '/mnt/linux/tools/testing/selftests/bpf' Into: libbpf: failed to find BTF for extern 'tcp_cong_avoid_ai' [27] section: -2 HINT: Please update your clang/llvm toolchain to at least cset abcdef123456 HINT: That is where clang started generating BTF information for extern functions in BPF code. ? :-) - Arnaldo
