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

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Date:   Tue, 10 Jan 2023 13:34:56 +0100
From:   Jiri Olsa <olsajiri@...il.com>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andres Freund <andres@...razel.de>,
        Quentin Monnet <quentin@...valent.com>,
        Roberto Sassu <roberto.sassu@...wei.com>,
        Christy Lee <christylee@...com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        bpf@...r.kernel.org, Michael Petlan <mpetlan@...hat.com>
Subject: Re: [PATCH v1 0/3] Assume libbpf 1.0 in build

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

other than that looks ok to me

Acked/Tested-by: Jiri Olsa <jolsa@...nel.org>

also for the 2 dependency patches

thanks,
jirka

>  delete mode 100644 tools/build/feature/test-libbpf-bpf_map_create.c
>  delete mode 100644 tools/build/feature/test-libbpf-bpf_object__next_map.c
>  delete mode 100644 tools/build/feature/test-libbpf-bpf_object__next_program.c
>  delete mode 100644 tools/build/feature/test-libbpf-bpf_prog_load.c
>  delete mode 100644 tools/build/feature/test-libbpf-bpf_program__set_insns.c
>  delete mode 100644 tools/build/feature/test-libbpf-btf__load_from_kernel_by_id.c
>  delete mode 100644 tools/build/feature/test-libbpf-btf__raw_data.c
> 
> -- 
> 2.39.0.314.g84b9a713c41-goog
>