Re: [PATCH 10/16] kernel-devsrc: copying rust-kernel source to $kerneldir/build

[Harish Sadineni <Harish.Sadineni@windriver.com>]

On 12/27/2025 8:39 PM, Bruce Ashfield wrote:
> CAUTION: This email comes from a non Wind River email account!
> Do not click links or open attachments unless you recognize the sender and know the content is safe.
>
> On Sat, Dec 27, 2025 at 7:33 AM <Harish.Sadineni@windriver.com> wrote:
>> From: Harish Sadineni <Harish.Sadineni@windriver.com>
>>
>> In sdk while running: 'make prepare' in kernel-source directory after enabling rust config,
>> it will throw errors since only makefile is present in rust kernel sources.
> Can you show exactly how much of the infrastructure is needed for
> make prepare to succeed ? We've gone through a lot of effort over
> the years to not copy whole directories, many which have plenty
> of source code just like the rust directories do.
>
> If we can just copy the Makefiles and Kbuild files + a few elements
> that are needed for regeneration, that is ideal.
Without this patch:

After populating the SDK and sourcing the environment, in the kernel 
source directory I run 'make rustavailable', then 'make scripts',
and enable Rust support (RUST) in the kernel configuration. When running 
'make prepare', the build fails.

The failure is due to missing Rust infrastructure. To understand the 
minimum required set, I attempted to add files incrementally based on 
the reported errors.
This resulted in the following dependency chain:

Initial failure during make prepare:

RUSTC   L rust/core.o
EXPORTS rust/exports_core_generated.h
make[2]: *** No rule to make target 'rust/bindings/bindings_helper.h',
            needed by 'rust/bindings/bindings_generated.rs'.  Stop.

After adding rust/bindings/bindings_helper.h:

make[2]: *** No rule to make target 'rust/bindgen_parameters',
            needed by 'rust/bindings/bindings_generated.rs'.  Stop.

After adding rust/bindgen_parameters:

BINDGEN rust/bindings/bindings_generated.rs
make[2]: *** No rule to make target 'rust/helpers/helpers.c',
            needed by 'rust/bindings/bindings_helpers_generated.rs'. Stop.

After adding rust/helpers/helpers.c, bindgen fails due to additional C 
source dependencies:

rust/helpers/helpers.c:10:10: fatal error: 'auxiliary.c' file not found
rust/helpers/helpers.c:11:10: fatal error: 'blk.c' file not found


At this point, it becomes apparent that make prepare continues to pull 
in further Rust and C source dependencies(chain of dependency is very 
large),
and in practice ends up requiring most of the Rust infrastructure rather 
than just a small set of Makefiles or files.

After applying this patch total size of rust directory  is 1.8MB.
> Bruce
>
>> Signed-off-by: Harish Sadineni <Harish.Sadineni@windriver.com>
>> ---
>>   meta/recipes-kernel/linux/kernel-devsrc.bb | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/meta/recipes-kernel/linux/kernel-devsrc.bb b/meta/recipes-kernel/linux/kernel-devsrc.bb
>> index 23a9093ede..1505a1d70c 100644
>> --- a/meta/recipes-kernel/linux/kernel-devsrc.bb
>> +++ b/meta/recipes-kernel/linux/kernel-devsrc.bb
>> @@ -139,6 +139,10 @@ do_install() {
>>           cd ${S}
>>
>>           cp -a scripts $kerneldir/build
>> +
>> +        if ${@bb.utils.contains('DISTRO_FEATURES', 'rust-kernel', 'true', 'false', d)}; then
>> +            cp -a rust ${kerneldir}/build
>> +        fi
>>
>>           # for v6.1+ (otherwise we are missing multiple default targets)
>>           cp -a --parents Kbuild $kerneldir/build 2>/dev/null || :
>> --
>> 2.49.0
>>
>
> --
> - Thou shalt not follow the NULL pointer, for chaos and madness await
> thee at its end
> - "Use the force Harry" - Gandalf, Star Trek II