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marfrit c7d8050cc9 Initial scaffold: daedalus-v4l2 sibling repo

V4L2 stateless decoder for Pi 5, backed by sibling
daedalus-fourier kernel library (VP9 + AV1 CDEF + H.264 video
decode kernels on VideoCore VII compute + ARM NEON).

Architecture locked 2026-05-18 by mfritsche per
daedalus-fourier/docs/phase8_scoping.md:
- Option B: Linux kernel V4L2 shim + userspace daemon (not
  v4l2loopback). Real /dev/videoNN; proper DRM PRIME for
  browser zero-copy.
- Option γ: dlopen FFmpeg at runtime as parser. No vendoring;
  fastest to v1.
- Sibling repo (this repo): V4L2-side work outside of
  daedalus-fourier so kernel-library API stays clean.

Components:
  kernel/ - Linux out-of-tree kernel module (GPLv2; V4L2
    device + chardev bridge to userspace daemon)
  daemon/ - userspace decoder daemon (BSD-2-Clause; links
    libdaedalus_core.a from sibling; dlopens FFmpeg)
  docs/   - architecture + 7-phase roadmap (8.1..8.7)
  include/ - shared headers between kernel and daemon

Roadmap (7 sub-phases, ~1 week each):
  8.1 kernel skeleton (/dev/videoNN with no-op ioctls)
  8.2 chardev bridge (kernel ↔ daemon ping-pong)
  8.3 daemon FFmpeg dlopen + parse path
  8.4 VP9 end-to-end via daedalus_dispatch_*
  8.5 dmabuf / DRM PRIME for zero-copy
  8.6 AV1 + H.264 codec support
  8.7 performance: hit 30fps@1080p (project floor)

No code yet — only README + design docs + directory structure.
First implementation work starts in Phase 8.1 next session.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2026-05-18 14:54:56 +00:00

README.md

Initial scaffold: daedalus-v4l2 sibling repo

2026-05-18 14:54:56 +00:00

README.md

kernel/ — daedalus-v4l2 Linux kernel module

Out-of-tree kernel module providing a V4L2 stateless decoder device that forwards work to a userspace daemon.

Status

Scaffold only. Phase 8.1 not yet started.

Build (when implemented)

make -C /lib/modules/$(uname -r)/build M=$(pwd)
sudo insmod daedalus_v4l2.ko
v4l2-ctl --list-devices  # confirm /dev/videoNN appears

Layout (planned)

Makefile — kbuild stub
daedalus_v4l2_main.c — module init + V4L2 device registration
daedalus_v4l2_chardev.c — /dev/daedalus-v4l2 chardev for daemon communication
daedalus_v4l2_v4l2.c — V4L2 ioctl dispatch (stateless controls)

License

GPLv2. Required for kernel module symbol compatibility.

Phase 8.1 starting point

Minimal example: register a /dev/videoNN that returns -ENOSYS on every ioctl. Validates that the kernel build works and v4l2-ctl can see the device.