Re: [OE-core] [PATCH v7 01/14] linux-yocto: conditionally add clang/rust/bindgen-cli-native to DEPENDS

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

On Wed, 2026-03-04 at 09:43 -0800, Sadineni, Harish via lists.openembedded.org wrote:
> From: Harish Sadineni <Harish.Sadineni@windriver.com>
> 
> Conditionally add 'clang-native', 'rust-native' and 'bindgen-cli-native' to 'DEPENDS'
> when Kernel Rust Support is enabled.
> 
> These tools are required for building Rust-enabled kernels and for
> generating Rust FFI bindings via bindgen during the kernel build.
> 
> This ensures the additional dependencies are only pulled in when
> Rust support is explicitly enabled, avoiding unnecessary native
> dependencies for non-Rust kernel builds.
> 
> Signed-off-by: Harish Sadineni <Harish.Sadineni@windriver.com>
> ---
>  meta/recipes-kernel/linux/linux-yocto.inc | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/meta/recipes-kernel/linux/linux-yocto.inc b/meta/recipes-kernel/linux/linux-yocto.inc
> index 4d0a726bb6..b7961bbcdf 100644
> --- a/meta/recipes-kernel/linux/linux-yocto.inc
> +++ b/meta/recipes-kernel/linux/linux-yocto.inc
> @@ -76,11 +76,14 @@ do_install:append(){
>  KERNEL_FEATURES:append:qemuall = " features/kernel-sample/kernel-sample.scc"
>  
>  KERNEL_DEBUG ?= ""
> +KERNEL_RUST_SUPPORT ?= ""
>  # These used to be version specific, but are now common dependencies.  New
>  # tools / dependencies will continue to be added in version specific recipes.
>  DEPENDS += '${@bb.utils.contains_any("ARCH", [ "x86", "arm64", "powerpc" ], "elfutils-native", "", d)}'
>  DEPENDS += "openssl-native util-linux-native"
>  DEPENDS += "gmp-native libmpc-native"
> +RUST_KERNEL_DEPENDS ?= "${@bb.utils.contains('KERNEL_RUST_SUPPORT', 'True', 'clang-native rust-native bindgen-cli-native', '', d)}"
> +DEPENDS += "${RUST_KERNEL_DEPENDS}"
>  
>  # Some options depend on CONFIG_PAHOLE_VERSION, so need to make pahole-native available before do_kernel_configme
>  do_kernel_configme[depends] += '${@bb.utils.contains("KERNEL_DEBUG", "True", "pahole-native:do_populate_sysroot", "", d)}'

I get the feeling we're still not quite agreeing on how to make the
enabling of the feature work. I'm suggesting we do something like this:

diff --git a/meta/classes-recipe/kernel-yocto.bbclass b/meta/classes-recipe/kernel-yocto.bbclass
index e53bf151941..9cc7568ab09 100644
--- a/meta/classes-recipe/kernel-yocto.bbclass
+++ b/meta/classes-recipe/kernel-yocto.bbclass
@@ -269,6 +269,9 @@ do_kernel_metadata() {
        KERNEL_FEATURES_FINAL=""
        if [ -n "${KERNEL_FEATURES}" ]; then
                for feature in ${KERNEL_FEATURES}; do
+                        if [ "$feature" = "rust" ]; then
+                                feature="features/kernel-rust/kernel-rust.scc"
+                        fi
                        feature_as_specified="$feature"
                        feature="$(echo $feature_as_specified | cut -d: -f1)"
                        feature_specifier="$(echo $feature_as_specified | cut -d: -f2)"

which means you can then simply add to your config:

KERNEL_FEATURES += "rust"

and things should be enabled. This patch would then become:

RUST_KERNEL_DEPENDS ?= "${@bb.utils.contains('KERNEL_FEATURES', 'rust', 'clang-native rust-native bindgen-cli-native', '', d)}"

Is there some reason we can't do something like this?

Cheers,

Richard