Messages in this thread | | | Subject | Re: [PATCH 0/3] perf/bpftool: Allow to link libbpf dynamically | From | Daniel Borkmann <> | Date | Wed, 27 Nov 2019 22:22:31 +0100 |
| |
On 11/27/19 9:24 PM, Andrii Nakryiko wrote: > On Wed, Nov 27, 2019 at 8:38 AM Alexei Starovoitov > <alexei.starovoitov@gmail.com> wrote: >> On Wed, Nov 27, 2019 at 1:48 AM Jiri Olsa <jolsa@kernel.org> 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 >>> >>> 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. >> 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.
+1, and would also be out of scope from a BPF library point of view.
> I second that. I'm currently working on adding few more APIs that I'd > like to keep unstable for a while, until we have enough real-world > usage (and feedback) accumulated, before we stabilize them. With > LIBBPF_API and a promise of stable API, we are going to over-stress > and over-design APIs, potentially making them either too generic and > bloated, or too limited (and thus become deprecated almost at > inception time). I'd like to take that pressure off for a super-new > and in flux APIs and not hamper the progress. > > I'm thinking of splitting off those non-stable, sort-of-internal APIs > into separate libbpf-experimental.h (or whatever name makes sense), > and let those be used only by tools like bpftool, which are only ever > statically link against libbpf and are ok with occasional changes to > those APIs (which we'll obviously fix in bpftool as well). Pahole > seems like another candidate that fits this bill and we might expose > some stuff early on to it, if it provides tangible benefits (e.g., BTF > dedup speeds ups, etc). > > Then as APIs mature, we might decide to move them into libbpf.h with > LIBBPF_API slapped onto them. Any objections?
I don't think adding yet another libbpf_experimental.h makes sense, it feels too much of an invitation to add all sort of random stuff in there. We already do have libbpf.h and libbpf_internal.h, so everything that does not relate to the /stable and public/ API should be moved from libbpf.h into libbpf_internal.h such as the netlink helpers, as one example, and bpftool can use these since in-tree changes also cover the latter just fine. So overall, same page, just reuse/improve libbpf_internal.h instead of a new libbpf_experimental.h.
Thanks, Daniel
| |