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From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: 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 13:00:11 -0700	[thread overview]
Message-ID: <CAEf4BzbK4jN7c8aa05xGyLm_FJKgywW8Ju8dA11VAJ9Nx8drVQ@mail.gmail.com> (raw)
In-Reply-To: <YMtgz+hcE/7iO7Ux@kernel.org>

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 :)

>
> - Arnaldo

  parent reply	other threads:[~2021-06-17 20:00 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-15 23:30 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 [this message]
2021-06-17 20:39             ` Arnaldo Carvalho de Melo
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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