From: Daniel Borkmann <daniel@iogearbox.net>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>,
"Alexei Starovoitov" <alexei.starovoitov@gmail.com>
Cc: 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>,
kubakici@wp.pl
Subject: Re: [PATCH bpf v3] bpftool: Allow to link libbpf dynamically
Date: Sat, 30 Nov 2019 00:56:49 +0100 [thread overview]
Message-ID: <9853054b-dc1f-35ba-ba3c-4d0ab01c8f14@iogearbox.net> (raw)
In-Reply-To: <87a78evl2v.fsf@toke.dk>
On 11/29/19 3:00 PM, Toke Høiland-Jørgensen wrote:
> Daniel Borkmann <daniel@iogearbox.net> writes:
>> On 11/28/19 5:07 PM, Toke Høiland-Jørgensen wrote:
>>> From: Jiri Olsa <jolsa@kernel.org>
[...]
>>> ifeq ($(srctree),)
>>> srctree := $(patsubst %/,%,$(dir $(CURDIR)))
>>> @@ -63,6 +72,19 @@ RM ?= rm -f
>>> FEATURE_USER = .bpftool
>>> FEATURE_TESTS = libbfd disassembler-four-args reallocarray zlib
>>> FEATURE_DISPLAY = libbfd disassembler-four-args zlib
>>> +ifdef LIBBPF_DYNAMIC
>>> + FEATURE_TESTS += libbpf
>>> + FEATURE_DISPLAY += libbpf
>>> +
>>> + # for linking with debug library run:
>>> + # make LIBBPF_DYNAMIC=1 LIBBPF_DIR=/opt/libbpf
>>
>> The Makefile already has BPF_DIR which points right now to
>> '$(srctree)/tools/lib/bpf/' and LIBBPF_PATH for the final one and
>> where $(LIBBPF_PATH)libbpf.a is expected to reside. Can't we improve
>> the Makefile to reuse and work with these instead of adding yet
>> another LIBBPF_DIR var which makes future changes in this area more
>> confusing? The libbpf build spills out libbpf.{a,so*} by default
>> anyway.
>
> I see what you mean; however, LIBBPF_DIR is meant to be specifically an
> override for the dynamic library, not just the path to libbpf.
>
> Would it be less confusing to overload the LIBBPF_DYNAMIC variable
> instead? I.e.,
>
> make LIBBPF_DYNAMIC=1
>
> would dynamically link against the libbpf installed in the system, but
>
> make LIBBPF_DYNAMIC=/opt/libbpf
>
> would override that and link against whatever is in /opt/libbpf instead?
> WDYT?
Hm, given perf tool has similar LIB*_DIR vars in place for its libs, it probably
makes sense to stick with this convention as well then. Perhaps better in this
case to just rename s/BPF_DIR/BPF_SRC_DIR/, s/LIBBPF_OUTPUT/LIBBPF_BUILD_OUTPUT/,
and s/LIBBPF_PATH/LIBBPF_BUILD_PATH/ to make their purpose more clear.
One thing that would be good to do as well for this patch is to:
i) Document both LIBBPF_DYNAMIC and LIBBPF_DIR in the Makefile comment you
added at the top along with a simple usage example.
ii) Extend tools/testing/selftests/bpf/test_bpftool_build.sh with a dynamic
linking test case, e.g. building libbpf into a temp dir and pointing
LIBBPF_DIR to it for bpftool LIBBPF_DYNAMIC=1 build.
Thanks,
Daniel
next prev parent reply other threads:[~2019-11-30 0:13 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
2019-11-29 10:24 ` Daniel Borkmann
2019-11-29 14:00 ` Toke Høiland-Jørgensen
2019-11-29 23:56 ` Daniel Borkmann [this message]
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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