Re: [PATCH v3] arm: rust: Enable Rust support for ARMv7

[Linus Walleij <linus.walleij@linaro.org>]

Hi Christian,

thanks for your patch!

Sorry for being late to the show. I missed this very nice patch
that was actually on my personal TODO but I have to much
to do and also I'm not smart with Rust, but I'm a big supporter.

On Thu, Jan 23, 2025 at 11:40 PM Christian Schrefl
<chrisi.schrefl@gmail.com> wrote:

> +       select HAVE_RUST if CPU_LITTLE_ENDIAN && CPU_32v7

Nothing in the patch series really explains this restriction, so it
should be in the commit message. Arnd mentions some atomics
etc, but we really need to know exactly why this is in the patch.

I'm a bit surprised by this since the rustc LLVM backend nowadays
support all old ARM ISAs. I would have expected:

select HAVE_RUST if AEABI

Ideally this should work on any ARM core, but it's fair to require
EABI.

The big reason: I think we want to be able to use Rust in kernel
core components sooner than ARMv5 goes away from the kernel.

If testing is the only issue, I can provide testing on ARMv4, v5,
ARMv5 BE etc, just tell me how to test. (But I guess it's more than
that...)

Yours,
Linus Walleij