Summary

pip install pillow on riscv64 Linux currently requires building from source (~5 min on a 1.6 GHz RISC-V SoC). Adding linux_riscv64 to the wheel build matrix would give riscv64 users a prebuilt wheel.

Evidence

The wheel imports and passes basic smoke tests on riscv64 Linux.

Suggested CI change

Workflow: .github/workflows/wheels.yml

Add riscv64 entries to the build-native-wheels matrix:

# In matrix.include, add:
- name: "manylinux_2_28 riscv64"
  platform: linux
  os: ubuntu-latest
  cibw_arch: riscv64
  build: "*manylinux*"

Add QEMU step (after checkout, before cibuildwheel):

- name: Set up QEMU
  if: matrix.cibw_arch == 'riscv64'
  uses: docker/setup-qemu-action@v3
  with:
    platforms: riscv64

Ecosystem context

• manylinux_2_28_riscv64 images are available on quay.io/pypa/ (landed in pypa/manylinux, 2025)
• cibuildwheel 3.x supports riscv64 via QEMU emulation
• auditwheel supports riscv64 platform tags
• maturin-action supports riscv64gc-unknown-linux-gnu cross-compilation
• Packages already shipping riscv64 wheels on PyPI: aiohttp, yarl, regex, markupsafe, charset-normalizer, rpds-py, multidict, propcache, watchfiles, rignore, setproctitle
• RISC-V hardware is shipping: SiFive HiFive, SpacemiT K1/K3, Sophgo SG2044 (64-core)

Our temporary index

While upstream support is pending, we maintain a PEP 503 index with 50+ riscv64 wheels for the Python ML/AI stack, built natively on RISC-V hardware.

Tracking repo: https://github.com/gounthar/riscv64-python-wheels