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

[Andrea Righi]

On Mon, Feb 13, 2023 at 02:19:38PM +0100, Miguel Ojeda wrote:
> On Fri, Feb 10, 2023 at 4:26 PM Andrea Righi <andrea.righi@xxxxxxxxxxxxx> 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.

This patch simply fixes scripts/is_rust_module.sh to recognize Rust
modules from "regular" C modules with certain versions of binutils, so
that BTF generation is properly skipped for Rust modules.

In this way both C and Rust modules can be loaded correctly (at least in
my tests I'm able load both with CONFIG_DEBUG_INFO_BTF enabled).

I haven't dropped the "RUST depends on !DEBUG_INFO_BTF" yet, but I think
with this fix is applied we can relax this constraint.

-Andrea

> 
> Also Cc'ing Daniel, Eric and Martin since they are the ones working on this.
> 
> Cheers,
> Miguel