Date: Tue, 7 Jul 2015 16:54:52 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Wang Nan <wangnan0@huawei.com>
Cc: ast@plumgrid.com, brendan.d.gregg@gmail.com, daniel@iogearbox.net,
        namhyung@kernel.org, masami.hiramatsu.pt@hitachi.com, paulus@samba.org,
        a.p.zijlstra@chello.nl, mingo@redhat.com, jolsa@kernel.org,
        dsahern@gmail.com, linux-kernel@vger.kernel.org, lizefan@huawei.com,
        hekuang@huawei.com, xiakaixu@huawei.com, pi3orama@163.com
Subject: Re: [RFC PATCH v10 23/50] perf tools: Make perf depend on libbpf
Message-ID: <20150707195452.GD3135@kernel.org>
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Em Wed, Jul 01, 2015 at 02:14:11AM +0000, Wang Nan escreveu:
> By adding libbpf into perf's Makefile, this patch enables perf to
> build libbpf during building if libelf is found and neither NO_LIBELF
> nor NO_LIBBPF is set. The newly introduced code is similar to libapi
> and libtraceevent building in Makefile.perf.
> 
> MANIFEST is also updated for 'make perf-*-src-pkg'.
> 
> Append make_no_libbpf to tools/perf/tests/make.
> 
> 'bpf' feature check is appended into default FEATURE_TESTS and
> FEATURE_DISPLAY, so perf will check API version of bpf in
> /path/to/kernel/include/uapi/linux/bpf.h. Which should not fail
> except when we are trying to port this code to an old kernel.
> 
> Error messages are also updated to notify users about the disable of
> BPF support of 'perf record' if libelf is missed or BPF API check
> failed.

Much better!

[acme@felicio linux]$ am /wb/1.patch 
Applying: perf tools: Make perf depend on libbpf
[perf/ebpf 53ec442e0d44] perf tools: Make perf depend on libbpf
 Author: Wang Nan <wangnan0@huawei.com>
 5 files changed, 45 insertions(+), 6 deletions(-)
[acme@felicio linux]$ m
make: Entering directory `/home/acme/git/linux/tools/perf'
  BUILD:   Doing 'make -j4' parallel build

Auto-detecting system features:
...                         dwarf: [ on  ]
...                         glibc: [ on  ]
...                          gtk2: [ on  ]
...                      libaudit: [ on  ]
...                        libbfd: [ on  ]
...                        libelf: [ on  ]
...                       libnuma: [ on  ]
...                       libperl: [ on  ]
...                     libpython: [ on  ]
...                      libslang: [ on  ]
...                     libunwind: [ on  ]
...            libdw-dwarf-unwind: [ on  ]
...                          zlib: [ on  ]
...                          lzma: [ on  ]
...                           bpf: [ on  ]

  CC       /tmp/build/perf/arch/common.o
  CC       /tmp/build/perf/util/abspath.o
  CC       /tmp/build/perf/builtin-bench.o

Auto-detecting system features:
...                        libelf: [ on  ]
...             libelf-getphdrnum: [ on  ]
...                   libelf-mmap: [ on  ]
...                           bpf: [ on  ]

  CC       /tmp/build/perf/libbpf.o
<SNIP>

Just a few nits, perhaps we should add what is the subsystem that is
asking for feature detection, so those two lines starting with
'Auto-detecting' would become:

Auto-detecting system features for tools/perf/:

<SNIP>

Auto-detecting system features for tools/lib/bpf/:

<SNIP>

------------------------------------

Also we need to reuse the tests, i.e. we're testing 'libelf'
twice, once for tools/perf, then for tools/lib/bpf, Jiri?

------------------------------------

Anyway, continuing...

- Arnaldo

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