From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
Yonghong Song <yhs@fb.com>, bpf <bpf@vger.kernel.org>,
dwarves@vger.kernel.org, siudin@fb.com
Subject: Re: latest pahole breaks libbpf CI and let's talk about staging
Date: Thu, 17 Jun 2021 17:39:29 -0300 [thread overview]
Message-ID: <YMuzAfK6vwbeN3XX@kernel.org> (raw)
In-Reply-To: <CAEf4BzbK4jN7c8aa05xGyLm_FJKgywW8Ju8dA11VAJ9Nx8drVQ@mail.gmail.com>
Em Thu, Jun 17, 2021 at 01:00:11PM -0700, Andrii Nakryiko escreveu:
> On Thu, Jun 17, 2021 at 7:48 AM Arnaldo Carvalho de Melo
> <arnaldo.melo@gmail.com> wrote:
> >
> > 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@gmail.com> 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.
> >
> > ?
> >
> > :-)
>
> I'd rather not :)
Not even a "please update clang?"
"-2" and "Error 255" doesn't seem that helpful :-\
- Arnaldo
next prev parent reply other threads:[~2021-06-17 20:39 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 23:30 latest pahole breaks libbpf CI and let's talk about staging Andrii Nakryiko
2021-06-16 14:56 ` Arnaldo Carvalho de Melo
2021-06-16 16:40 ` Arnaldo Carvalho de Melo
2021-06-16 20:41 ` Arnaldo Carvalho de Melo
2021-06-16 22:36 ` Andrii Nakryiko
2021-06-17 14:48 ` Arnaldo Carvalho de Melo
2021-06-17 19:53 ` Arnaldo Carvalho de Melo
2021-06-17 20:03 ` Andrii Nakryiko
2021-06-17 20:41 ` Arnaldo Carvalho de Melo
2021-06-17 21:56 ` Andrii Nakryiko
2021-06-17 20:00 ` Andrii Nakryiko
2021-06-17 20:39 ` Arnaldo Carvalho de Melo [this message]
2021-06-17 21:52 ` Andrii Nakryiko
2021-06-18 17:21 ` Arnaldo Carvalho de Melo
2021-06-16 17:40 ` Andrii Nakryiko
2021-06-16 18:25 ` Arnaldo Carvalho de Melo
2021-06-16 22:38 ` Andrii Nakryiko
2021-06-17 0:16 ` Arnaldo Carvalho de Melo
2021-06-17 4:26 ` Andrii Nakryiko
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