On Wed, Nov 27, 2019 at 1:49 AM Jiri Olsa [off-list ref] wrote:

hi,
adding support to link bpftool with libbpf dynamically,
and config change for perf.

It's now possible to use:
  $ make -C tools/bpf/bpftool/ LIBBPF_DYNAMIC=1

I wonder what's the motivation behind these changes, though? Why is
linking bpftool dynamically with libbpf is necessary and important?
They are both developed tightly within kernel repo, so I fail to see
what are the huge advantages one can get from linking them
dynamically.

which will detect libbpf devel package with needed version,
and if found, link it with bpftool.

It's possible to use arbitrary installed libbpf:
  $ make -C tools/bpf/bpftool/ LIBBPF_DYNAMIC=1 LIBBPF_DIR=/tmp/libbpf/

I based this change on top of Arnaldo's perf/core, because
it contains libbpf feature detection code as dependency.
It's now also synced with latest bpf-next, so Toke's change
applies correctly.

Also available in:
  git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
  libbpf/dyn

thanks,
jirka


---
Jiri Olsa (2):
      perf tools: Allow to specify libbpf install directory
      bpftool: Allow to link libbpf dynamically

Toke Høiland-Jørgensen (1):
      libbpf: Export netlink functions used by bpftool

 tools/bpf/bpftool/Makefile        | 40 +++++++++++++++++++++++++++++++++++++++-
 tools/build/feature/test-libbpf.c |  9 +++++++++
 tools/lib/bpf/libbpf.h            | 22 +++++++++++++---------
 tools/lib/bpf/libbpf.map          |  7 +++++++
 tools/lib/bpf/nlattr.h            | 15 ++++++++++-----
 tools/perf/Makefile.config        | 27 ++++++++++++++++++++-------
 6 files changed, 98 insertions(+), 22 deletions(-)