perf tools: Allow to link with libbpf dynamicaly

Currently we support only static linking with kernel's libbpf
(tools/lib/bpf). This patch adds libbpf package detection and support to
link perf with it dynamically.

The libbpf package status is displayed with:

  $ make VF=1
  Auto-detecting system features:
  ...
  ...                        libbpf: [ on  ]

It's not checked by default, because it's quite new.  Once it's on most
distros we can switch it on.

For the same reason it's not added to the test-all check.

Perf does not need advanced version of libbpf, so we can check just for
the base bpf_object__open function.

Adding new compile variable to detect libbpf package and link bpf
dynamically:

  $ make LIBBPF_DYNAMIC=1
    ...
    LINK     perf
  $ ldd perf | grep bpf
    libbpf.so.0 => /lib64/libbpf.so.0 (0x00007f46818bc000)

If libbpf is not installed, build stops with:

  Makefile.config:486: *** Error: No libbpf devel library found,\
  please install libbpf-devel.  Stop.

Committer testing:

  $ make LIBBPF_DYNAMIC=1 -C tools/perf O=/tmp/build/perf
  make: Entering directory '/home/acme/git/perf/tools/perf'
    BUILD:   Doing 'make -j8' parallel build
  Makefile.config:493: *** Error: No libbpf devel library found, please install libbpf-devel.  Stop.
  make[1]: *** [Makefile.perf:225: sub-make] Error 2
  make: *** [Makefile:70: all] Error 2
  make: Leaving directory '/home/acme/git/perf/tools/perf'
  $

Signed-off-by: Jiri Olsa <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Toke Høiland-Jørgensen <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Andrii Nakryiko <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: Jesper Dangaard Brouer <[email protected]>
Cc: Martin KaFai Lau <[email protected]>
Cc: Michael Petlan <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Yonghong Song <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

0 files changed, 0 insertions, 0 deletions