Re: [PATCH] arch: um: rust: Add i386 support for Rust

[Ard Biesheuvel]

On Wed, 5 Jun 2024 at 08:22, Nathan Chancellor <nathan@xxxxxxxxxx> wrote:
>
> Hi David,
>
> Just a fly by comment on style, I don't have much to say content :)
>
> On Wed, Jun 05, 2024 at 06:40:50AM +0800, David Gow wrote:
> > At present, Rust in the kernel only supports 64-bit x86, so UML has
> > followed suit. However, it's significantly easier to support 32-bit i386
> > on UML than on bare metal, as UML does not use the -mregparm option
> > (which alters the ABI), which is not yet supported by rustc[1].
> >
> > Add support for CONFIG_RUST on um/i386, by adding a new target config to
> > generate_rust_target, and replacing various checks on CONFIG_X86_64 to
> > also probably like  support CONFIG_X86_32.
> >
> > We still use generate_rust_target, rather than a built-in rustc target,
> > in oPrder to match x86_64, provide a future place for -mregparm, and more
> > easily disable floating point instructions.
> >
> > With these changes, the KUnit tests pass with:
> > kunit.py run --make_options LLVM=1 --kconfig_add CONFIG_RUST=y
> > --kconfig_add CONFIG_64BIT=n --kconfig_add CONFIG_FORTIFY_SOURCE=n
> >
> > An earlier version of these changes was proposed on the Rust-for-Linux
> > github[2].
> >
> > [1]: https://github.com/rust-lang/rust/issues/116972
> > [2]: https://github.com/Rust-for-Linux/linux/pull/966
> >
> > Signed-off-by: David Gow <davidgow@xxxxxxxxxx>
> ...
> > -ifdef CONFIG_X86_64
> > +ifneq ($(or $(CONFIG_X86_64),$(CONFIG_X86_32)),)
>
> These configurations are mutually exclusive, so would it look more
> readable to have it be:
>
>
> ifeq ($(CONFIG_X86_32)$(CONFIG_X86_64),y)
>

Or simply

ifdef CONFIG_X86