picolibc-bsd

A redistribution of picolibc with all copyleft-licensed files removed.

See the upstream README for picolibc documentation.

Why this fork exists

Picolibc is a lightweight C library for embedded systems. The core library sources are permissively licensed (BSD-3-Clause and similar), but the upstream repository includes a small number of copyleft-licensed files:

• test/ directory - GPLv2+ test suite files
• scripts/GeneratePicolibcCrossFile.sh - AGPLv3+ build helper
• COPYING.GPL2 - GPL license text

These files are not needed to build or use picolibc, but their presence in git history can complicate license compliance for projects that vendor picolibc as a submodule or dependency.

This fork provides a clean tree containing only permissively-licensed files, suitable for embedding without copyleft concerns.

History structure

The first commit is the upstream picolibc source at the base version tag with copyleft files excluded. The second commit adds fork tooling. Future upstream updates are cherry-picked one commit at a time with copyleft files filtered, preserving individual commit granularity.

Updating from upstream

Updates can be triggered manually via the Update from Upstream GitHub Actions workflow, which takes an upstream version tag (e.g., 1.9.0) as input. The workflow:

1. Detects the current base version from the latest *-bsd tag
2. Runs scripts/import-upstream.sh to cherry-pick upstream commits with copyleft files filtered out
3. Opens a PR for review
4. On merge, a <version>-bsd tag and GitHub release are created automatically

Manual import

To import locally instead of using the workflow:

scripts/import-upstream.sh <from-tag> <to-tag>
# e.g., scripts/import-upstream.sh 1.8.11 1.9.0

After importing, tag the result and push:

git tag <to-tag>-bsd
git push origin main --tags

License scanning

This repository uses scancode-toolkit in CI to verify that no copyleft-licensed files are present. See .github/workflows/license-check.yml.

License

All source code files in this repository are under permissive licenses (BSD-3-Clause, BSD-2-Clause, MIT, ISC, and similar). The COPYING.picolibc file contains a license inventory that references copyleft licenses for documentation purposes - those files have been removed from the tree. See COPYING.picolibc for per-file license details.

Attribution

picolibc is created and maintained by Keith Packard and contributors. See the upstream repository for full contributor history.