Re: [PATCH bpf-next 2/6] libbpf: Collect static vs global info about functions

Alexei Starovoitov
2020-01-08T20:10:24Z

On Wed, Jan 08, 2020 at 05:57:55PM +0000, Song Liu wrote:
>
>
> > On Jan 8, 2020, at 2:25 AM, Toke Høiland-Jørgensen <toke@redhat.com> wrote:
> >
> > Alexei Starovoitov <ast@kernel.org> writes:
> >
> >> Collect static vs global information about BPF functions from ELF file and
> >> improve BTF with this additional info if llvm is too old and doesn't emit it on
> >> its own.
> >
> > Has the support for this actually landed in LLVM yet? I tried grep'ing
> > in the commit log and couldn't find anything...
> >
> > [...]
> >> @@ -313,6 +321,7 @@ struct bpf_object {
> >> bool loaded;
> >> bool has_pseudo_calls;
> >> bool relaxed_core_relocs;
> >> + bool llvm_emits_func_linkage;
> >
> > Nit: s/llvm/compiler/? Presumably GCC will also support this at some
> > point?
>
> Echoing this nit (and other references to llvm). Otherwise,

sure. will rename to compiler, but I think you folks are overly optimistic
about gcc. Even basic stuff doesn't work yet. I doubt we will see BTF
emitted by gcc this year.