Re: [PATCH bpf-next v2 0/4] libbpf: ABI versioning and documentation

[Alexei Starovoitov <alexei.starovoitov@gmail.com>]

On Fri, Nov 23, 2018 at 04:44:31PM -0800, Andrey Ignatov wrote:
> This patch set adds ABI versioning and documentation to libbpf.
> 
> Patch 1 renames btf_get_from_id to btf__get_from_id to follow naming
> convention.
> Patch 2 adds version script and has more details on ABI versioning.
> Patch 3 adds simple check that all global symbols are versioned.
> Patch 4 documents a few aspects of libbpf API and ABI in dev process.
> 
> v1->v2:
> * add patch from Martin KaFai Lau <kafai@fb.com> to rename btf_get_from_id;
> * add documentation for libbpf API and ABI.

All looks great to me.
Thank you for adding the doc.
Applied to bpf-next.

We need to discuss the release model and version bumps.
For example I don't think it's necessary to bump the version
and update libbpf.map every time the new function is added.
I mean we can synchronize release of libbpf with the release of the kernel
or release it every N weeks.
So if we add new api functions during this release we can simply
add them to libbpf.map while keeping the version as 0.0.1

I'd also consider the first 0.0.1 release to be experimental
while we're figuring out the right process.
For the next kernel/libbpf release I propose to bump it to 1.0.0

Another idea is to version it just like kernel and make libbpf version
always equal kernel version.
But I think that would be an overkill. libbpf isn't tightly coupled to
the kernel. Like we just merged the patch (prog_name/map_name probing
that allows new libbpf to work with older kernel.