Re: [PATCH bpf-next] bpf: Document the pahole release info related to libbpf in bpf_devel_QA.rst

From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Yonghong Song <yhs@fb.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>,
	Jonathan Corbet <corbet@lwn.net>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
	linux-doc@vger.kernel.org, netdev@vger.kernel.org,
	bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
	Xuefeng Li <lixuefeng@loongson.cn>
Subject: Re: [PATCH bpf-next] bpf: Document the pahole release info related to libbpf in bpf_devel_QA.rst
Date: Fri, 23 Apr 2021 15:20:13 -0300	[thread overview]
Message-ID: <YIMP3flCE6uwYp69@kernel.org> (raw)
In-Reply-To: <221ef66a-a7e4-14b7-e085-6062e8547b11@fb.com>

Em Thu, Apr 22, 2021 at 09:12:19PM -0700, Yonghong Song escreveu:
> 
> 
> On 4/22/21 6:23 PM, Tiezhu Yang wrote:
> > pahole starts to use libbpf definitions and APIs since v1.13 after the
> > commit 21507cd3e97b ("pahole: add libbpf as submodule under lib/bpf").
> > It works well with the git repository because the libbpf submodule will
> > use "git submodule update --init --recursive" to update.
> > 
> > Unfortunately, the default github release source code does not contain
> > libbpf submodule source code and this will cause build issues, the tarball
> > from https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ is same with
> > github, you can get the source tarball with corresponding libbpf submodule
> > codes from
> > 
> > https://fedorapeople.org/~acme/dwarves
> > 
> > This change documents the above issues to give more information so that
> > we can get the tarball from the right place, early discussion is here:
> > 
> > https://lore.kernel.org/bpf/2de4aad5-fa9e-1c39-3c92-9bb9229d0966@loongson.cn/
> > 
> > Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> > ---
> >   Documentation/bpf/bpf_devel_QA.rst | 13 +++++++++++++
> >   1 file changed, 13 insertions(+)
> > 
> > diff --git a/Documentation/bpf/bpf_devel_QA.rst b/Documentation/bpf/bpf_devel_QA.rst
> > index d05e67e..253496a 100644
> > --- a/Documentation/bpf/bpf_devel_QA.rst
> > +++ b/Documentation/bpf/bpf_devel_QA.rst
> > @@ -449,6 +449,19 @@ from source at
> >   https://github.com/acmel/dwarves
> > +pahole starts to use libbpf definitions and APIs since v1.13 after the
> > +commit 21507cd3e97b ("pahole: add libbpf as submodule under lib/bpf").
> > +It works well with the git repository because the libbpf submodule will
> > +use "git submodule update --init --recursive" to update.
> > +
> > +Unfortunately, the default github release source code does not contain
> > +libbpf submodule source code and this will cause build issues, the tarball
> > +from https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ is same with
> > +github, you can get the source tarball with corresponding libbpf submodule
> > +codes from
> > +
> > +https://fedorapeople.org/~acme/dwarves
> > +
> 
> Arnaldo, could you take a look at this patch? Thanks!

Sure, he documented it as I expected from a previous interaction about
this. Would be good to add a paragraph stating how to grab libbpf and
graft it even on a tarball not containing it tho.

Bonus points if the cmake files gets changed in a way that this gets
notified to the user in the error message.

But these suggestions can come in another patch, for this I can give my:

Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com>

- Arnaldo

> >   Some distros have pahole version 1.16 packaged already, e.g.
> >   Fedora, Gentoo.