Re: [PATCH v1 0/2] RISC-V: enable rust

From: Conor Dooley
Date: Mon Feb 12 2024 - 15:38:08 EST


On Mon, Feb 12, 2024 at 08:17:31PM +0000, Conor Dooley wrote:
> On Mon, Feb 12, 2024 at 08:11:21PM +0100, Miguel Ojeda wrote:
> > On Mon, Feb 12, 2024 at 8:02 PM Ramon de C Valle <rcvalle@xxxxxxxxxx> wrote:
> > >
> > > Sorry for the late reply. Sami might be the best person to answer this, but KCFI (not CFI) tests are lowered by passes that are architecture specific (see https://reviews.llvm.org/D119296), so we'd need to add support for RISC-V. There is no additional work required in the Rust compiler besides enabling it for the new target.
> >
> > Thanks a lot Ramon!
> >
> > Then for RISC-V let's go for the `depends on` for the moment, and we
> > can remove when the support lands for RISC-V (ideally when someone has
> > managed to boot it at least under some configuration).
>
> If all you want is a boot under some configuration, that's not
> difficult. After all, I found the original issue by booting a kernel
> with CFI_CLANG enabled on the C side...

Also, regardless of depends on on RISC-V, things will still be broken
on arm64 and x86_64, since KCFI is not enabled in rustc there either?

> > There is no additional work required in the Rust compiler besides enabling it for the new target.
>
> This is not super clear though, it says "in the Rust compiler", not "in
> the kernel's buildsystem".

I realise I was not clear either. What I meant was that this talks about
rustc and not kbuild, so what is meant by "the new target" is not clear.
Do arm64 and x86_64 have functional support, so adding RISC-V in rustc
is needed, or did you mean for the new target in the kernel?


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