Re: [OE-core] [PATCH 2/4] kernel-yocto-rust: use clang toolchain for riscv64 when Rust is enabled

["Mathieu Dubois-Briand" <mathieu.dubois-briand@bootlin.com>]

On Mon Jul 6, 2026 at 1:29 PM CEST, Harish via lists.openembedded.org Sadineni wrote:
> From: Harish Sadineni <Harish.Sadineni@windriver.com>
>
> Enable LLVM/Clang toolchain for riscv64 kernel builds when Rust support
> is enabled, as Rust is only supported with LLVM toolchains for this
> architecture.
>
> This aligns with upstream kernel Rust architecture requirements as
> documented in:
> https://docs.kernel.org/rust/arch-support.html
>
> Signed-off-by: Harish Sadineni <Harish.Sadineni@windriver.com>
> ---

Hi Harish,

Thanks for your patch.

>  meta/recipes-kernel/linux/linux-yocto.inc | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/meta/recipes-kernel/linux/linux-yocto.inc b/meta/recipes-kernel/linux/linux-yocto.inc
> index 4e230d405a..ee0d5abaeb 100644
> --- a/meta/recipes-kernel/linux/linux-yocto.inc
> +++ b/meta/recipes-kernel/linux/linux-yocto.inc
> @@ -91,3 +91,7 @@ do_devshell:prepend() {
>      d.setVar("HOSTPKG_CONFIG", "pkg-config-native")
>      d.appendVar("OE_TERMINAL_EXPORTS", " HOSTPKG_CONFIG")
>  }
> +
> +# For riscv64, Rust support in kernel only works with LLVM/Clang only.
> +# https://docs.kernel.org/rust/arch-support.html
> +TOOLCHAIN:riscv64 = "${@bb.utils.contains('KERNEL_FEATURES', 'rust', 'clang', '', d)}"

So I believe this is wrong, as you are setting TOOLCHAIN to nothing if
rust is not in KERNEL_FEATURES.

This is failing on the autobuilder with:
Parsing recipes...ERROR: ParseError at /srv/pokybuild/yocto-worker/qemuriscv64/build/layers/openembedded-core/meta/classes-global/base.bbclass:36: Could not inherit file classes/toolchain/.bbclass
ERROR: Parsing halted due to errors, see error messages above

https://autobuilder.yoctoproject.org/valkyrie/#/builders/45/builds/1836

Can you have a look at the issue?

Thanks,
Mathieu

-- 
Mathieu Dubois-Briand, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com