Re: [OE-core] [PATCH v2 03/15] rust: install Rust library sources for 'make rustavailable' support

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

On 1/7/2026 12:29 AM, Randy MacLeod wrote:
> On 2026-01-05 11:24 a.m., Harish Sadineni wrote:
>>
>> On 12/30/2025 9:28 PM, Richard Purdie 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 Tue, 2025-12-30 at 06:15 -0800, Sadineni, Harish via 
>>> lists.openembedded.org wrote:
>>>> From: Harish Sadineni <Harish.Sadineni@windriver.com>
>>>>
>>>> The `make rustavailable` process (1) expects the Rust standard 
>>>> library source files (e.g., `lib.rs`)
>>>> to be present in the `library/` directory under `rustlib/src/rust/`.
>>>>
>>>> This patch ensures the required sources are available by:
>>>> - Copying the `library/` directory from the Rust source tree into 
>>>> `${TMPDIR}/work-shared/rust`
>>>>    during the snapshot setup.
>>>> - Installing the `library/` directory into 
>>>> `${SDKPATHNATIVE}/usr/lib/rustlib/src/rust` for the
>>>>    `nativesdk` class, making them available in them available in sdk
>>>>
>>>> 1) See the kernel tree for Documentation/rust/quick-start.rst in 
>>>> the section: Requirements: Building
>>>>
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/rust/quick-start.rst#n145 
>>>>
>>>>
>>>> Signed-off-by: Harish Sadineni <Harish.Sadineni@windriver.com>
>>>> ---
>>>>   meta/recipes-devtools/rust/rust_1.91.1.bb | 17 +++++++++++++++++
>>>>   1 file changed, 17 insertions(+)
>>>>
>>>> diff --git a/meta/recipes-devtools/rust/rust_1.91.1.bb 
>>>> b/meta/recipes-devtools/rust/rust_1.91.1.bb
>>>> index a25f65f674..7644ecf2d2 100644
>>>> --- a/meta/recipes-devtools/rust/rust_1.91.1.bb
>>>> +++ b/meta/recipes-devtools/rust/rust_1.91.1.bb
>>>> @@ -63,6 +63,16 @@ do_rust_setup_snapshot () {
>>>>           done
>>>>       fi
>>>>   }
>>>> +
>>>> +do_rust_setup_snapshot:append:class-native () {
>>>> +   if ${@bb.utils.contains('DISTRO_FEATURES', 'rust-kernel', 
>>>> 'true', 'false', d)}; then
>>>> +         if [ ! -d "${TMPDIR}/work-shared/rust" ]; then
>>>> +                mkdir -p ${TMPDIR}/work-shared/rust
>>>> +                cp -r ${RUSTSRC}/library ${TMPDIR}/work-shared/rust/.
>>>> +         fi
>>>> +   fi
>>>> +}
>>>> +
>>>>   addtask rust_setup_snapshot after do_unpack before do_configure
>>>>   addtask do_test_compile after do_configure do_rust_gen_targets
>>>>   do_rust_setup_snapshot[dirs] += "${WORKDIR}/rust-snapshot"
>>>> @@ -314,6 +324,13 @@ rust_do_install:class-nativesdk() {
>>>>        export 
>>>> CARGO_TARGET_${RUST_HOST_TRIPLE}_RUNNER="\$OECORE_NATIVE_SYSROOT/lib/${SDKLOADER}"
>>>>        export CC_$RUST_HOST_CC="${CCACHE}${HOST_PREFIX}gcc"
>>>>        EOF
>>>> +
>>>> +    if ${@bb.utils.contains('DISTRO_FEATURES', 'rust-kernel', 
>>>> 'true', 'false', d)}; then
>>>> +           if [ ! -d ${D}${SDKPATHNATIVE}/usr/lib/rustlib/src/rust 
>>>> ]; then
>>>> +                mkdir -p 
>>>> ${D}${SDKPATHNATIVE}/usr/lib/rustlib/src/rust
>>>> +                cp -r --no-preserve=ownership  ${S}/library 
>>>> ${D}${SDKPATHNATIVE}/usr/lib/rustlib/src/rust/
>>>> +           fi
>>>> +    fi
>>>>   }
>>>>
>>>>   FILES:${PN} += "${base_prefix}/environment-setup.d"
>>> The commit message should mention the size of these files.
>> Ok sure, I will add file size in v3.
>>> Does this make sense as a distro feature or should we just do this 
>>> all the time?
>> This is suggestion from Bruce that we take it as distro feature.
>> https://lists.openembedded.org/g/openembedded-core/message/225256
>
>
> Richard mentioned this thread in today's tech call when I asked for 
> commentson the rust-kernel PR.
>
> Yes, the high level requirement is to have a DISTRO_FEATURE but 
> common, infrastructure parts
> such as this code that just copies a hopefully small number of files 
> around,
> and is part of the rust recipe, could and likely be done regardless of 
> the rust-kernel DISTRO_FEATURE.
>

Ok sure, We will remove the dependency on DISTRO_FEATURE  for copying 
the library directory from rust recipe.
>
>
> We don't want the rust recipe to change based on a kernel config 
> unless we *really* have to
> since that essentially doubles the testing that should be done or 
> leaves a gap in testing of the
> rust builds. If you do that for the kernel first, then another recipe 
> later, soon you have a maintenance mess.
>
> Also if the kernel needs these files, then it's likely that other 
> software will need it as well.
> You should analyze why the kernel needs these files and why other 
> recipes do not. Perhaps any
> kernel-like image will have the same requirement. Is there a baremetal 
> image  using rust anywhere
> that you can use to check on that? I looked but all I found was:
> https://github.com/ahcbb6/baremetal-helloqemu-rust
> Anyway, let's focus on the linux kernel's requirements for now.
>
>
> So, how many files are needed and how much FS space do they use?
>

The file size of the library directory is around 50MB.
>
>
> What are other build systems (gentoo for example) doing with their 
> Rust builds to satisfy the kernel's rust requirements?
>

I will check and update on this.
>
>
>>
>> In future when rust is default in kernel we can change this, But till 
>> then it is good to have it as a distro feature.
>>> Do the nativesdk components get packaged separately? If they were, we
>>> could then make that an SDK feature instead.
>> No, We are not packaging it separately.
>
>
> The questions seems to be whether we should create a separate 
> packaging rule.
>

Now by default it is getting packaged with nativesdk-rust, Do we need a 
separate packaging for libraries/files that being installed for rust in 
kernel support?
>
>
>>> What happens for on target kernel module development? Shouldn't 
>>> there be a target package too?
>> Yes, I have made the necessary changes to include Rust library for 
>> target as well and have tested Rust-based kernel module development 
>> on the target.
>> I will send updated patches with v3.
>
>
> Before you spend time on polishing v3 please explain what your 
> workflow is, step by step,
> so we can be sure that things makes sense from a high level.
>
We will update the rust recipe to copy the required libs to target image 
and then the below steps to be followed :
- Build the image by adding the required tools via IMAGE_INSTALL:append 
( e.g kernel-devsrc, gcc, rust, cargo, bindgen-cli etc..).
- In /usr/src/kernel, run "make rustavailable" to verify Rust support 
(This step will check all supporting tools are available for rust 
support in kernel).
- Run "make menuconfig" and enable "CONFIG_RUST".
- Run "make scripts" and "make prepare".
- Write a kernel module in Rust & build the module using "make", which 
generates the "module_name.ko" file.
- Load the module using "insmod module_name.ko".

Thanks,
Harish

> ../Randy
>
>
>>
>> Thanks,
>> Harish
>>> Cheers,
>>>
>>> Richard
>
>
> -- 
> # Randy MacLeod
> # Wind River Linux