Add nat20lib kernel module example and br environment. by werwurm · Pull Request #98 · aurora-opensource/libnat20

werwurm · 2026-04-29T16:35:43Z

Add a kernel module that provides libnat20 functionality to linux kernel
modules. Also add a configuration to build a minimal linux image with
buildroot and run in on qemu and a workflow to test build nat20lib.ko

Add a kernel module that provides libnat20 functionality to linux kernel modules. Also add a configuration to build a minimal linux image with buildroot and run in on qemu and a workflow to test build nat20lib.ko

github-actions · 2026-04-29T16:37:54Z

LCOV of commit `3ded408` during lcov-test-coverage-report #188

Summary coverage rate:
  lines......: 95.7% (3013 of 3147 lines)
  functions..: 99.1% (230 of 232 functions)
  branches...: 87.2% (1646 of 1887 branches)

Files changed coverage rate: n/a

Copilot

Pull request overview

Adds a Linux kernel-module packaging of libnat20 (as an example) and a Buildroot external tree + QEMU run tooling to build/test the module in CI.

Changes:

Introduces examples/linux/nat20lib kernel module sources/build files and exports libnat20 symbols.
Adds a Buildroot br_external tree (package definition, configs, bootstrap + dev helper scripts, QEMU runner) to build a minimal image/module.
Adds a GitHub Actions workflow to build and verify nat20lib.ko, plus expands license-check patterns for the new file types.

Reviewed changes

Copilot reviewed 14 out of 16 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
examples/linux/nat20lib/mod.c	New kernel module entry/exit and symbol exports for libnat20.
examples/linux/nat20lib/Makefile	Wrapper Makefile for building/installing the external module.
examples/linux/nat20lib/Kbuild	Kbuild definition compiling nat20 sources into `nat20lib.ko`.
examples/linux/br_external/utils/envsetup.sh	Dev environment helper script for building/rebuilding Buildroot artifacts.
examples/linux/br_external/run-qemu.sh	Script to boot the built kernel/rootfs in QEMU.
examples/linux/br_external/package/nat20lib/nat20lib.mk	Buildroot package definition for the nat20lib kernel module.
examples/linux/br_external/package/nat20lib/Config.in	Buildroot config option for enabling nat20lib.
examples/linux/br_external/external.mk	Buildroot external tree package include.
examples/linux/br_external/external.desc	Buildroot external tree descriptor.
examples/linux/br_external/configs/qemu_linux_defconfig	Kernel defconfig used by the Buildroot environment.
examples/linux/br_external/bootstrap.sh	Bootstrap script to set up out-of-tree Buildroot build directory.
examples/linux/br_external/Config.in	Top-level Buildroot external Config.in sourcing nat20lib package.
.github/workflows/linux-kmod-build.yml	CI workflow to build and verify `nat20lib.ko` via Buildroot.
.github/license-check/license-config.json	Adds license-check patterns for new file extensions/paths.

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…RIDE_DIR

smacdude

I'm not an expert on all of this, but Claude found some issues that I think should at least be questioned.

smacdude · 2026-05-05T18:44:32Z

+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 #v4.3.0
+        with:
+          path: ${{ runner.temp }}/buildroot.build
+          key: buildroot-${{ hashFiles('examples/linux/br_external/configs/qemu_br_defconfig', 'examples/linux/br_external/configs/qemu_linux_defconfig') }}


According to Claude:
cache key is incomplete. hashFiles(...) covers only the two defconfigs. The Buildroot version (2025.08.1) is hardcoded in bootstrap.sh, so bumping it won't invalidate the cache → stale toolchain. Include bootstrap.sh (and probably the br_external/** tree) in the key

Added bootstra.sh. I don't think we need br_external/**. It will just add noise.

smacdude · 2026-05-05T18:57:56Z

+            ensure_popd make linux-rebuild nat20lib-rebuild all
+            ;;
+        *)
+            ensure_popd make $1-rebuild all


Should this line contain quotes?

I don't think it makes much of a difference. Make targets shouldn't have spaces. Apparently, it is technically possible, but do we want to encourage this?

smacdude · 2026-05-05T19:10:53Z

+
+obj-m := nat20lib.o
+ccflags-y := -I $(src)/../../../include
+ccflags-y += -I $(srctree)


Is this line and the next line changing compiler options for the Linux source, and if so, is that safe?

This is not needed for newer kernels which use gnu11. But this code won't compile with gnu90. So we may have a problem with older kernels. I'll remove this for now.

timhirsh

Approving GH Actions 👍

seidelrj · 2026-05-07T14:52:31Z

+# <https://www.gnu.org/licenses/>.
+
+name: NAT20
+desc: Provides NAT20 related packages package.


Suggested change

desc: Provides NAT20 related packages package.

desc: Provides NAT20 related packages.

Looks like this co-pilot finding wasn't resolved.

Add nat20lib kernel module example and br environment.

67ca3fc

Add a kernel module that provides libnat20 functionality to linux kernel modules. Also add a configuration to build a minimal linux image with buildroot and run in on qemu and a workflow to test build nat20lib.ko

werwurm requested a review from a team as a code owner April 29, 2026 16:35

werwurm added 2 commits April 29, 2026 09:57

Fixup lint and add Makefiles to license checker.

4070f76

Make bootstrap executable

de1ea2a

werwurm requested review from Copilot and timhirsh April 29, 2026 17:12

Copilot started reviewing on behalf of werwurm April 29, 2026 17:13 View session

werwurm requested review from seidelrj and smacdude April 29, 2026 17:17

Copilot AI reviewed Apr 29, 2026

View reviewed changes

werwurm added 3 commits April 29, 2026 14:44

Use prebuild toolchain and stop building qemu from scratch.

36bc192

address comments and also resolve circular dependency when using OVER…

44c8f8f

…RIDE_DIR

Do not use relative paths

6627ce3

smacdude reviewed May 5, 2026

View reviewed changes

Address comments.

4b64988

werwurm requested a review from smacdude May 5, 2026 20:52

smacdude approved these changes May 5, 2026

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timhirsh approved these changes May 7, 2026

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seidelrj approved these changes May 7, 2026

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typo

3ded408

seidelrj approved these changes May 7, 2026

View reviewed changes

werwurm merged commit a7286d9 into main May 7, 2026
10 checks passed

	desc: Provides NAT20 related packages package.
	desc: Provides NAT20 related packages.

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werwurm commented Apr 29, 2026

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LCOV of commit 3ded408 during lcov-test-coverage-report #188

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github-actions Bot commented Apr 29, 2026 •

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LCOV of commit `3ded408` during lcov-test-coverage-report #188