Re: [RFC 0/4] BTF archive with unmodified pahole+toolchain

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Thu, Aug 07, 2025 at 03:25:34PM -0300, Arnaldo Carvalho de Melo wrote:
> If we use completely unmodified libbpf, bpftool, etc, the "BTF archive"
> in the resulting vmlinux .BTF ELF section is still consumable, but just
> the first "CU" (the first .o .BTF ELF section) is visible, the one for
> init/main.o:
 
> acme@number:~/git/linux$ bpftool version
> bpftool v7.5.0
> using libbpf v1.5
> features: llvm, skeletons
> acme@number:~/git/linux$
 
> acme@number:~/git/bpf-next$ bpftool btf dump file ~/vmlinux-v6.16.0+.btf_archive format c | wc -l
> 11361
> acme@number:~/git/linux$ bpftool btf dump file ../build/v6.16.0+/init/main.o format c | wc -l
> 11361
> acme@number:~/git/linux$
 
> Furthermore:

> acme@number:~/git/linux$ bpftool btf dump file ../build/v6.16.0+/init/main.o format c > a
> acme@number:~/git/linux$ bpftool btf dump file ~/vmlinux-v6.16.0+.btf_archive format c > b

Oops, the expected:

acme@number:~/git/linux$ diff a b
acme@number:~/git/linux$

> acme@number:~/git/linux$

- Arnaldo