Re: [PATCH v1 0/3] Assume libbpf 1.0 in build

From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Jiri Olsa <olsajiri@gmail.com>
Cc: Ian Rogers <irogers@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Andres Freund <andres@anarazel.de>,
	Quentin Monnet <quentin@isovalent.com>,
	Roberto Sassu <roberto.sassu@huawei.com>,
	Christy Lee <christylee@fb.com>,
	Andrii Nakryiko <andrii@kernel.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	bpf@vger.kernel.org, Michael Petlan <mpetlan@redhat.com>
Subject: Re: [PATCH v1 0/3] Assume libbpf 1.0 in build
Date: Tue, 10 Jan 2023 10:36:31 -0300	[thread overview]
Message-ID: <Y71p30zGtzUtrvt2@kernel.org> (raw)
In-Reply-To: <Y71bcMYQ26eroc2W@krava>

Em Tue, Jan 10, 2023 at 01:34:56PM +0100, Jiri Olsa escreveu:
> On Mon, Jan 09, 2023 at 12:34:21PM -0800, Ian Rogers wrote:
> > libbpf 1.0 was a major change in API. Perf has partially supported
> > older libbpf's but an implementation may be:
> > ..
> >        pr_err("%s: not support, update libbpf\n", __func__);
> >        return -ENOTSUP;
> > ..
> > 
> > Rather than build a binary that would fail at runtime it is
> > preferrential just to build libbpf statically and link against
> > that. The static version is in the kernel tools tree and newer than
> > 1.0.
> > 
> > These patches change the libbpf test to only pass when at least
> > version 1.0 is installed, then remove the conditional build and
> > feature logic.
> > 
> > The issue is discussed here:
> > https://lore.kernel.org/lkml/20230106151320.619514-1-irogers@google.com/
> > 
> > Ian Rogers (3):
> >   tools build: Pass libbpf feature only if libbpf 1.0+
> >   perf build: Remove libbpf pre-1.0 feature tests
> >   perf bpf: Remove pre libbpf 1.0 conditional logic
> > 
> >  tools/build/feature/Makefile                  |  7 --
> >  .../feature/test-libbpf-bpf_map_create.c      |  8 ---
> >  .../test-libbpf-bpf_object__next_map.c        |  8 ---
> >  .../test-libbpf-bpf_object__next_program.c    |  8 ---
> >  .../build/feature/test-libbpf-bpf_prog_load.c |  9 ---
> >  .../test-libbpf-bpf_program__set_insns.c      |  8 ---
> >  .../test-libbpf-btf__load_from_kernel_by_id.c |  8 ---
> >  .../build/feature/test-libbpf-btf__raw_data.c |  8 ---
> >  tools/build/feature/test-libbpf.c             |  4 ++
> >  tools/perf/Makefile.config                    | 37 +----------
> >  tools/perf/util/bpf-event.c                   | 66 -------------------
> >  tools/perf/util/bpf-loader.c                  | 18 -----
> >  tools/perf/util/bpf_counter.c                 | 18 -----
> >  13 files changed, 5 insertions(+), 202 deletions(-)
> 
> nice, I like that.. I was able to build perf on fedora
> with (dynamic) and without (static) libbpf 1.0 
> 
> I hope supporting allowing dynamic link just with libbpf 1.0
> won't mess up backport world too much.. cc-ing Michael

Yeah, would be nice to hear from Michael and other distro maintainers.

- Arnaldo

> other than that looks ok to me
> 
> Acked/Tested-by: Jiri Olsa <jolsa@kernel.org>
> 
> also for the 2 dependency patches

ok!