From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Jiri Olsa <jolsa@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Jiri Olsa <jolsa@kernel.org>, lkml <linux-kernel@vger.kernel.org>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
Ingo Molnar <mingo@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Michael Petlan <mpetlan@redhat.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>
Subject: Re: [PATCH bpf v3] bpftool: Allow to link libbpf dynamically
Date: Fri, 29 Nov 2019 09:24:53 +0100 [thread overview]
Message-ID: <87v9r3um22.fsf@toke.dk> (raw)
In-Reply-To: <20191129081251.GA14169@krava>
Jiri Olsa <jolsa@redhat.com> writes:
> On Thu, Nov 28, 2019 at 05:07:12PM +0100, Toke Høiland-Jørgensen wrote:
>
> SNIP
>
>> ifeq ($(srctree),)
>> srctree := $(patsubst %/,%,$(dir $(CURDIR)))
>> @@ -63,6 +72,19 @@ RM ?= rm -f
>> FEATURE_USER = .bpftool
>> FEATURE_TESTS = libbfd disassembler-four-args reallocarray zlib
>> FEATURE_DISPLAY = libbfd disassembler-four-args zlib
>> +ifdef LIBBPF_DYNAMIC
>> + FEATURE_TESTS += libbpf
>> + FEATURE_DISPLAY += libbpf
>> +
>> + # for linking with debug library run:
>> + # make LIBBPF_DYNAMIC=1 LIBBPF_DIR=/opt/libbpf
>> + ifdef LIBBPF_DIR
>> + LIBBPF_CFLAGS := -I$(LIBBPF_DIR)/include
>> + LIBBPF_LDFLAGS := -L$(LIBBPF_DIR)/$(libdir_relative)
>> + FEATURE_CHECK_CFLAGS-libbpf := $(LIBBPF_CFLAGS)
>> + FEATURE_CHECK_LDFLAGS-libbpf := $(LIBBPF_LDFLAGS)
>> + endif
>> +endif
>>
>> check_feat := 1
>> NON_CHECK_FEAT_TARGETS := clean uninstall doc doc-clean doc-install doc-uninstall
>> @@ -88,6 +110,18 @@ ifeq ($(feature-reallocarray), 0)
>> CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
>> endif
>>
>> +ifdef LIBBPF_DYNAMIC
>> + ifeq ($(feature-libbpf), 1)
>> + # bpftool uses non-exported functions from libbpf, so just add the dynamic
>> + # version of libbpf and let the linker figure it out
>> + LIBS := -lbpf $(LIBS)
>
> nice, so linker will pick up the missing symbols and we
> don't need to check on particular libbpf version then
Yup, exactly. I verified with objdump that the end result is a
dynamically linked bpftool with LIBBPF_DYNAMIC is set, and a statically
linked one if it isn't; so the linker seems to be smart enough to just
figure out how to do the right thing :)
-Toke
next prev parent reply other threads:[~2019-11-29 8:25 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-27 9:48 [PATCH 0/3] perf/bpftool: Allow to link libbpf dynamically Jiri Olsa
2019-11-27 9:48 ` [PATCH 1/3] perf tools: Allow to specify libbpf install directory Jiri Olsa
2019-11-27 9:48 ` [PATCH 2/3] libbpf: Export netlink functions used by bpftool Jiri Olsa
2019-11-27 9:48 ` [PATCH 3/3] bpftool: Allow to link libbpf dynamically Jiri Olsa
2019-11-27 13:38 ` Quentin Monnet
2019-11-27 14:15 ` Jiri Olsa
2019-11-27 14:24 ` Arnaldo Carvalho de Melo
2019-11-27 14:31 ` Quentin Monnet
2019-11-27 15:48 ` Arnaldo Carvalho de Melo
2019-11-27 15:52 ` Quentin Monnet
2019-11-27 15:59 ` Arnaldo Carvalho de Melo
2019-11-27 14:29 ` Quentin Monnet
2019-11-27 16:41 ` Alexei Starovoitov
2019-11-27 16:37 ` [PATCH 0/3] perf/bpftool: " Alexei Starovoitov
2019-11-27 18:44 ` Arnaldo Carvalho de Melo
2019-11-27 20:24 ` Andrii Nakryiko
2019-11-27 21:22 ` Daniel Borkmann
2019-11-27 22:47 ` Jiri Olsa
2019-11-28 9:06 ` Toke Høiland-Jørgensen
2019-11-28 14:53 ` [PATCH bpf v2] bpftool: " Toke Høiland-Jørgensen
2019-11-28 15:32 ` Quentin Monnet
2019-11-28 15:52 ` Toke Høiland-Jørgensen
2019-11-28 16:07 ` [PATCH bpf v3] " Toke Høiland-Jørgensen
2019-11-28 17:30 ` Quentin Monnet
2019-11-29 8:12 ` Jiri Olsa
2019-11-29 8:24 ` Toke Høiland-Jørgensen [this message]
2019-11-29 10:24 ` Daniel Borkmann
2019-11-29 14:00 ` Toke Høiland-Jørgensen
2019-11-29 23:56 ` Daniel Borkmann
2019-12-02 8:59 ` Jiri Olsa
2019-12-02 17:09 ` [PATCH 0/3] perf/bpftool: " Andrii Nakryiko
2019-12-02 18:08 ` Toke Høiland-Jørgensen
2019-12-02 18:42 ` Andrii Nakryiko
2019-12-02 18:54 ` Arnaldo Carvalho de Melo
2019-12-02 19:21 ` Jiri Olsa
2019-12-02 19:54 ` Andrii Nakryiko
2019-12-02 20:02 ` Jiri Olsa
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