Re: [PATCH] rust: fix regexp in scripts/is_rust_module.sh

[Martin Rodriguez Reboredo <yakoyoku@gmail.com>]

On Mon, Feb 13, 2023 at 1:19 PM Miguel Ojeda <ojeda@kernel.org> wrote:
> On Fri, Feb 10, 2023 at 4:26 PM Andrea Righi <andrea.righi@canonical.com> wrote:
> >
> > nm can use "R" or "r" to show read-only data sections, but
> > scripts/is_rust_module.sh can only recognize "r", so with some versions
> > of binutils it can fail to detect if a module is a Rust module or not.
>
> Do you know which versions? If so, it would be nice to document it here.
>
> > Moreover, with this patch applied I can also relax the constraint of
> > "RUST depends on !DEBUG_INFO_BTF" and build a kernel with Rust and BTF
> > enabled at the same time (of course BTF generation is still skipped for
> > Rust modules).
>
> Even if that build succeeds, can you load the modules? i.e. the
> constraint was there due to
> https://github.com/Rust-for-Linux/linux/issues/735.

Issue was that the kernel couldn't even load C modules, Rust CUs must be
skipped in vmlinux for it to work, and because of that the constraint
!DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE [1] cannot be relaxed until
version 1.24+ of Pahole is the minimum requirement by the kernel. I'm OK
with this change but keep in mind that it won't remedy that condition.

Link: https://lore.kernel.org/bpf/20230111152050.559334-1-yakoyoku@gmail.com/ [1]