Re: [OE-core] [PATCH v2] kernel-arch: limit KERNEL_TOOLCHAIN to the kbuild recipes

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Fri, 2026-07-24 at 13:59 +0900, mark.yang via lists.openembedded.org wrote:
> From: "mark.yang" <mark.yang@lge.com>
> 
> u-boot and barebox inherit kernel-arch for the ARCH mapping, so since
> 0e3756efe0 ("kernel-arch: add KERNEL_TOOLCHAIN to switch the whole
> kernel toolchain") KERNEL_TOOLCHAIN = "clang" switches them too. That
> swaps u-boot's gcc-cross dependency for clang-cross, but its kbuild
> hardcodes ${CROSS_COMPILE}gcc:
> 
>   /bin/sh: 1: x86_64-oe-linux-gcc: not found
> 
> Full log: https://errors.yoctoproject.org/Errors/Build/242654/
> 
> Pin TOOLCHAIN back to gcc in kernel-arch and set it from
> KERNEL_TOOLCHAIN in kernel.bbclass, module-base and make-mod-scripts.
> 
> Signed-off-by: mark.yang <mark.yang@lge.com>
> ---
> v2: add a comment explaining why kernel-arch keeps TOOLCHAIN pinned
>     to gcc
> 
> The v2 series was merged, so this carries the remaining v3 3/3 delta
> (<20260720231714.1631366-1-mark.yang@lge.com>) as a follow-up fix.
> 
>  meta/classes-recipe/kernel-arch.bbclass                      | 5 ++++-
>  meta/classes-recipe/kernel.bbclass                           | 1 +
>  meta/classes-recipe/module-base.bbclass                      | 1 +
>  meta/recipes-kernel/make-mod-scripts/make-mod-scripts_1.0.bb | 1 +
>  4 files changed, 7 insertions(+), 1 deletion(-)

I really don't like having to set the same thing in multiple places, it
will cause a maintenance nightmare in the future. The kernel classes
are getting too convoluted and too much of a twisted maze already.

There is very little u-boot and barebox actually need from the class
anyway. Instead, I suggest we move the arch function to the python
library and then have u-boot and barebox call what they need from
there.

I've some patches on master-next which start to do this.

Cheers

Richard