On 12/30/2025 9:28 PM, Richard Purdie wrote:

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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.

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?

What are other build systems (gentoo for example) doing with their Rust builds to satisfy the kernel's rust requirements?

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.

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.

../Randy

Thanks,
Harish

Cheers,

Richard

-- 
# Randy MacLeod
# Wind River Linux