drawfs

drawfs is a prototype kernel device and message protocol for a minimal graphics path:

• A userspace client writes framed messages to /dev/draw
• The kernel queues replies and events back to the same file descriptor via read(2)
• Shared pixel surfaces are exposed to userspace via an explicit MAP_SURFACE ioctl followed by mmap(2)

This repository is intended as a stepping stone for integrating a fast, predictable drawing path into SemaDraw.

Platform

• FreeBSD 15
• Python 3 (tests)
• Zig 0.15.2 (optional, for SemaDraw integration work)

Quick start

This repo includes build.sh to install the kernel sources into /usr/src, build the module, and load it.

./build.sh install
./build.sh build
./build.sh load
./build.sh test

The test action runs the current end to end tests in tests/.

Repository layout

• sys/dev/drawfs/ kernel device implementation
  • drawfs.c - device operations, session lifecycle, message dispatch
  • drawfs_surface.c - surface management, mmap backing
  • drawfs_frame.c - frame validation and building
• sys/modules/drawfs/ kmod build glue
• tests/ python and C tests (step based)
  • drawfs_test.py - shared test helpers and protocol encoding
  • drawfs_dump.py - debug tool for decoding raw frames
• docs/ design and protocol documentation

License

See LICENSE.