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References: <20230106142537.607399-1-irogers@google.com> <20230106142537.607399-2-irogers@google.com>
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From:   Mike Leach <mike.leach@linaro.org>
Date:   Fri, 6 Jan 2023 15:12:21 +0000
Message-ID: <CAJ9a7VjE4PzEe+Gu_KPi3JEw3TKQpC70yZrLRT+EmaEGDRLnEQ@mail.gmail.com>
Subject: Re: [PATCH v2 2/2] perf build: Fix build error when NO_LIBBPF=1
To:     Ian Rogers <irogers@google.com>
Cc:     linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
        bpf@vger.kernel.org, acme@kernel.org, peterz@infradead.org,
        mingo@redhat.com, mark.rutland@arm.com,
        alexander.shishkin@linux.intel.com, jolsa@kernel.org,
        namhyung@kernel.org
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Precedence: bulk

On Fri, 6 Jan 2023 at 14:25, Ian Rogers <irogers@google.com> wrote:
>
> The $(LIBBPF) target should only be a dependency of prepare if the
> static version of libbpf is needed. Add a new LIBBPF_STATIC variable
> that is set by Makefile.config. Use LIBBPF_STATIC to determine whether
> the CFLAGS, etc. need updating and for adding $(LIBBPF) as a prepare
> dependency.
>
> As Makefile.config isn't loaded for "clean" as a target, always set
> LIBBPF_OUTPUT regardless of whether it is needed for $(LIBBPF). This
> is done to minimize conditional logic for $(LIBBPF)-clean.
>
> This issue and an original fix was reported by Mike Leach in:
> https://lore.kernel.org/lkml/20230105172243.7238-1-mike.leach@linaro.org/
>
> Fixes: 746bd29e348f ("perf build: Use tools/lib headers from install path")
> Reported-by: Mike Leach <mike.leach@linaro.org>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/Makefile.config |  2 ++
>  tools/perf/Makefile.perf   | 21 ++++++++++++---------
>  2 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index c2504c39bdcb..7c00ce0a7464 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -602,6 +602,8 @@ ifndef NO_LIBELF
>            dummy := $(error Error: No libbpf devel library found, please install libbpf-devel);
>          endif
>        else
> +        # Libbpf will be built as a static library from tools/lib/bpf.
> +       LIBBPF_STATIC := 1
>         CFLAGS += -DHAVE_LIBBPF_BTF__LOAD_FROM_KERNEL_BY_ID
>          CFLAGS += -DHAVE_LIBBPF_BPF_PROG_LOAD
>          CFLAGS += -DHAVE_LIBBPF_BPF_OBJECT__NEXT_PROGRAM
> diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> index 13e7d26e77f0..4e370462e7e1 100644
> --- a/tools/perf/Makefile.perf
> +++ b/tools/perf/Makefile.perf
> @@ -303,10 +303,12 @@ ifneq ($(OUTPUT),)
>  else
>    LIBBPF_OUTPUT = $(CURDIR)/libbpf
>  endif
> -LIBBPF_DESTDIR = $(LIBBPF_OUTPUT)
> -LIBBPF_INCLUDE = $(LIBBPF_DESTDIR)/include
> -LIBBPF = $(LIBBPF_OUTPUT)/libbpf.a
> -CFLAGS += -I$(LIBBPF_OUTPUT)/include
> +ifdef LIBBPF_STATIC
> +  LIBBPF_DESTDIR = $(LIBBPF_OUTPUT)
> +  LIBBPF_INCLUDE = $(LIBBPF_DESTDIR)/include
> +  LIBBPF = $(LIBBPF_OUTPUT)/libbpf.a
> +  CFLAGS += -I$(LIBBPF_OUTPUT)/include
> +endif
>
>  ifneq ($(OUTPUT),)
>    LIBSUBCMD_OUTPUT = $(abspath $(OUTPUT))/libsubcmd
> @@ -393,10 +395,8 @@ endif
>  export PERL_PATH
>
>  PERFLIBS = $(LIBAPI) $(LIBPERF) $(LIBSUBCMD) $(LIBSYMBOL)
> -ifndef NO_LIBBPF
> -  ifndef LIBBPF_DYNAMIC
> -    PERFLIBS += $(LIBBPF)
> -  endif
> +ifdef LIBBPF_STATIC
> +  PERFLIBS += $(LIBBPF)
>  endif
>
>  # We choose to avoid "if .. else if .. else .. endif endif"
> @@ -756,12 +756,15 @@ prepare: $(OUTPUT)PERF-VERSION-FILE $(OUTPUT)common-cmds.h archheaders $(drm_ioc
>         $(arch_errno_name_array) \
>         $(sync_file_range_arrays) \
>         $(LIBAPI) \
> -       $(LIBBPF) \
>         $(LIBPERF) \
>         $(LIBSUBCMD) \
>         $(LIBSYMBOL) \
>         bpf-skel
>
> +ifdef LIBBPF_STATIC
> +prepare: $(LIBBPF)
> +endif
> +
>  $(OUTPUT)%.o: %.c prepare FORCE
>         $(Q)$(MAKE) -f $(srctree)/tools/build/Makefile.build dir=$(build-dir) $@
>
> --
> 2.39.0.314.g84b9a713c41-goog
>

Tested-by: Mike Leach <mike.leach@linaro.org>

-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK