[PATCH v4 2/2] arm64: rust: Enable Rust support for AArch64

[Miguel Ojeda]

On Tue, Oct 24, 2023 at 4:18 PM Pratham Patel <thefirst1322 at gmail.com> wrote:
>
> This comes from a nobody (quite literally my first email on the kernel
> mailing list), but I would rather that the support for AArch64 BE be
> not added at all. My reasoning for this is because the rustc target
> `aarch64_be-unknown-linux-gnu` is in the tier 3 of support.

We are aware of the tier list support, but please note that e.g. for
x86, we are not even using one of the built-in targets (for the moment
at least), and that we use a range of other unstable features. It is
under discussion between the two projects how these details will be
properly supported.

> but from a developer's and packager's
> perspective, this will lead to a few wasted hours until the
> metaphorical person figures out why said Rust code failed to build for
> AArch64 BE.

Why would the code fail to build? i.e. as far as I understand, Boqun
successfully compiled and QEMU-booted a BE image.

If you mean that it could stop compiling at any point because it is
not officially supported, then note that we pin the compiler, and that
it also applies to the rest of the code due to other unstable features
too, which is why we need to get the Rust project to support the
kernel properly for the use cases we need (not just targets, but also
features).

Also please note that, even if everything else was formally supported,
it would still be a good idea to add this support early (possibly with
a warning or gate or similar if not intended to be used by end users
yet) so that we have the first big-endian target around.

> P.S. This is my first time sending an email to a mailing list, sorry
> if I mucked something up.

The content looks fine :)

However, I think the proper `In-Reply-To` header is not there so Lore
gets confused -- did you use the suggested parameters at the bottom of
e.g. [1]?

[1] https://lore.kernel.org/rust-for-linux/CAM+6MoE1DyOay-fMWQP0hsenz174hSuGJnKM7symh0C-y1mqZw@mail.gmail.com/

Cheers,
Miguel