Add riscv64 (linux_riscv64) wheel to PyPI releases

Add linux_riscv64 wheel to PyPI releases

Summary

pip install tiktoken on riscv64 Linux currently requires building from source (~10 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/build_wheels.yml

Add a new job using maturin-action directly (cibuildwheel doesn't support riscv64 well for Rust extensions):

build_wheels_riscv64:
  runs-on: ubuntu-latest
  steps:
  - uses: actions/checkout@v4
  - uses: PyO3/maturin-action@v1
    with:
      target: riscv64gc-unknown-linux-gnu
      manylinux: auto
      args: --release --out dist
  - uses: actions/upload-artifact@v4
    with:
      name: wheels-riscv64
      path: dist

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

Start by reading .github/workflows/build_wheels.yml and the existing wheel-building jobs, then compare their artifact and release handling with the proposed PyO3/maturin-action job targeting riscv64gc-unknown-linux-gnu. Done means the workflow produces a linux_riscv64 wheel that is included in the PyPI release and passes the stated riscv64 import and smoke-test checks.