Files
daedalus-v4l2/kernel
marfrit 5965805d86 Phase 8.7: media controller + multi-frame streaming verification
Two pieces — both shipped:

1. Media controller binding closes the last v4l2-compliance
   failure from 8.6 (DECODER_CMD, which requires has_media on
   stateless decoders) and unlocks the V4L2 request API for
   libva-v4l2-request.

2. Multi-frame streaming test exercises the daemon's
   AVCodecContext state preservation across many REQ_DECODE
   calls — Phase 8.6's tests pushed exactly one keyframe per
   invocation; real content has P-frame references.

Compliance now reaches **49/49 passing.**

Kernel (kernel/daedalus_v4l2_main.{c,h}):
- Added `struct media_device mdev` to daedalus_dev.
- media_device_init(&mdev) BEFORE v4l2_device_register so
  v4l2-core sees v4l2_dev.mdev = &mdev and binds the m2m
  entities into the graph during register.
- After video_register_device:
  v4l2_m2m_register_media_controller(..., MEDIA_ENT_F_PROC_VIDEO_DECODER)
  then media_device_register so userspace sees the complete
  graph in /dev/mediaN with the decoder entity tagged.
- daedalus_remove unwinds in reverse: unregister media,
  unregister mc, unregister video, release m2m, unregister
  v4l2, cleanup mdev.
- Error paths added for both new failure points.

Test harness (tools/test_m2m_stream.c, new):
- Multi-frame V4L2 m2m client: parses IVF → 4-deep buffer
  rings on both queues → per-frame QBUF/DQBUF loop →
  concatenates decoded NV12 to output file. Returns 0 only
  if every input frame decoded without error.
- Same codec vocabulary as test_m2m_decode (vp9 | av1 |
  h264 via 5th arg).

Verification on hertz (Pi 5, 6.12.75+rpt-rpi-2712):

v4l2-compliance: 49 tests, 49 passed, 0 failed, 0 warnings.

  $ v4l2-ctl --list-devices
  daedalus-fourier V3D7+NEON (platform:daedalus_v4l2):
        /dev/video0
        /dev/media3

VP9 320×240 30 frames (1 keyframe + 29 P-frames, 3.46 MB
NV12): byte-for-byte match vs `ffmpeg -i in.ivf -pix_fmt
nv12 -f rawvideo`.

VP9 1920×1080 10 frames (31 MB NV12 through the dmabuf
path): byte-for-byte match vs same reference command.

Daemon log shows cookies 1..30 all completing cleanly in
order; lazily-opened AVCodecContext maintains reference
frames across the chardev round-trips.

Clean SIGTERM + rmmod, no oops/WARN.

Roadmap update (docs/roadmap.md):
- 8.7 marked closed with closure-doc reference.
- 8.8 reshaped: perf profiling, QPU dispatch substitution
  via daedalus-fourier, multi-frame AV1/H.264, HDR (P010M).

Per correctness-before-speed:
- Order-correct media controller lifecycle (init → bind
  v4l2_dev → register video → register mc → register
  media; reverse for teardown).
- 4-deep buffer rings on both queues — the scheduler
  actually pipelines multiple in-flight cookies through
  the chardev (not just one-at-a-time as in 8.5/8.6 tests).
- Bit-exact comparison against ffmpeg, not "looks right."
- All resource paths cleaned on every error branch.

Phase 8.8 next: profile daemon hot loops, dlopen
daedalus-fourier from the daemon, swap FFmpeg per-block
calls for daedalus_dispatch_* where the kernel matches,
target 30fps@1080p from 30fps-floor-is-fine memory.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-18 16:21:58 +00:00
..

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.