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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Tue, 16 Nov 2021 10:21:19 -0800
Message-ID: <CAEf4BzbOnpL-=2Xi1DOheUtzc-JG5FmHqdvs4B_+0OeaCTgY=w@mail.gmail.com>
Subject: Re: [PATCH 1/1] Documentation: Add minimum pahole version
To:     Arnaldo Carvalho de Melo <acme@kernel.org>
Cc:     Jonathan Corbet <corbet@lwn.net>,
        Alexei Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Jiri Olsa <jolsa@redhat.com>, bpf <bpf@vger.kernel.org>,
        Networking <netdev@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Tue, Nov 16, 2021 at 7:40 AM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> A report was made in https://github.com/acmel/dwarves/issues/26 about
> pahole not being listed in the process/changes.rst file as being needed
> for building the kernel, address that.
>
> Link: https://github.com/acmel/dwarves/issues/26
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Andrii Nakryiko <andrii@kernel.org>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> Cc: Jiri Olsa <jolsa@redhat.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: bpf@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
>  Documentation/process/changes.rst | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
> index e35ab74a0f804b04..c45f167a1b6c02a4 100644
> --- a/Documentation/process/changes.rst
> +++ b/Documentation/process/changes.rst
> @@ -35,6 +35,7 @@ GNU make               3.81             make --version
>  binutils               2.23             ld -v
>  flex                   2.5.35           flex --version
>  bison                  2.0              bison --version
> +pahole                 1.16             pahole --version
>  util-linux             2.10o            fdformat --version
>  kmod                   13               depmod -V
>  e2fsprogs              1.41.4           e2fsck -V
> @@ -108,6 +109,14 @@ Bison
>  Since Linux 4.16, the build system generates parsers
>  during build.  This requires bison 2.0 or later.
>
> +pahole:
> +-------
> +
> +Since Linux 5.2 the build system generates BTF (BPF Type Format) from DWARF in
> +vmlinux, a bit later from kernel modules as well, if CONFIG_DEBUG_INFO_BTF is

I'd probably emphasize a bit more that pahole is required only if
CONFIG_DEBUG_INFO_BTF is selected by moving "If CONFIG_DEBUG_INFO_BTF
is selected, " to the front. But either way looks good.

Acked-by: Andrii Nakryiko <andrii@kernel.org>

> +selected.  This requires pahole v1.16 or later. It is found in the 'dwarves' or
> +'pahole' distro packages or from https://fedorapeople.org/~acme/dwarves/.
> +
>  Perl
>  ----
>
> --
> 2.31.1
>