Alexei Starovoitov [off-list ref] writes:

On Wed, Nov 27, 2019 at 1:48 AM Jiri Olsa [off-list ref] wrote:

quoted

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

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.

I don't like it.
Especially Toke's patch to expose netlink as public and stable libbpf
api.

Figured you might say that :)

bpftools needs to stay tightly coupled with libbpf (and statically
linked for that reason).
Otherwise libbpf will grow a ton of public api that would have to be stable
and will quickly become a burden.

I can see why you don't want to expose the "internal" functions as
LIBBPF_API. Doesn't *have* to mean we can't link bpftool dynamically
against the .so version of libbpf, though; will see if I can figure out
a clean way to do that...

-Toke