marfrit
9415b7e0f7
Out-of-tree Linux kernel module registering /dev/videoNN. Phase 8.1 scope: skeleton only — VIDIOC_QUERYCAP works, no codec ioctls / no vb2_queue / no controls yet. Real V4L2 plumbing throughout per "correctness before speed": platform_device + v4l2_device + video_device, properly nested with error paths and devm_kzalloc-managed lifetime. Per-cycle 9 discipline ports to kernel code: SPDX header, kernel coding style (8-tab, static-by-default), kerneldoc on structs, no shortcuts. Files (~250 LOC total): - kernel/Makefile — out-of-tree kbuild with checkpatch target - kernel/daedalus_v4l2_main.c — module init/exit + probe/remove Verification on hertz (Pi 5, 6.12.75+rpt-rpi-2712): - Builds clean with -Wall -Wextra. No warnings. - modprobe / rmmod round-trip clean. No dmesg taints beyond the expected "out-of-tree taint" line. - v4l2-ctl --list-devices shows: "daedalus-fourier V3D7+NEON (platform:daedalus_v4l2): /dev/video0" - VIDIOC_QUERYCAP returns driver/card/bus/caps as specified. - v4l2-compliance: 44/48 passing. The 4 failures are exactly the format/buffer ioctls Phase 8.2 will implement (ENUM_FMT, G_FMT, Scaling, REQBUFS) — not skeleton bugs, legitimately-absent features. Documentation: docs/phase_8_1_closure.md captures full verification output + Phase 8.2 plan. Phase 8.1 acceptance criteria met: - ✓ /dev/videoNN appears via v4l2-ctl --list-devices - ✓ VIDIOC_QUERYCAP responds with sensible values - ✓ rmmod is clean (no kref leaks) - ✓ v4l2-compliance passes except for explicit Phase 8.2 work Next: Phase 8.2 chardev bridge for kernel ↔ daemon IPC. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
daedalus-v4l2
V4L2 stateless decoder for the Raspberry Pi 5 / CM5, backed by the
daedalus-fourier kernel library (VP9 + AV1 CDEF + H.264 video
decode kernels on VideoCore VII compute + ARM NEON).
Status: scaffold (2026-05-18). Architecture locked per daedalus-fourier session memory; implementation not yet begun.
What this is
Sibling repo to daedalus-fourier (the kernel library; cycles 1-9 closed).
A two-piece userspace + kernel-module stack that exposes a V4L2
stateless decoder interface (/dev/videoNN) so that
libva-v4l2-request-fourier → firefox-fourier /
chromium-fourier can drive it the same way they drive existing
hardware-decode pipelines on Pi 5 / RK3588.
+-----------------------------------------------------------+
| firefox-fourier / chromium-fourier (existing) |
+-----------------------------------------------------------+
| VA-API |
+-----------------------------------------------------------+
| libva-v4l2-request-fourier (existing, sibling project) |
+-----------------------------------------------------------+
| V4L2 stateless ioctl uAPI |
+-----------------------------------------------------------+
| daedalus-v4l2 kernel module (`kernel/`) |
| - registers /dev/videoNN |
| - parses V4L2 stateless ioctls (VP9/AV1/H.264 controls) |
| - forwards bitstream + controls to userspace daemon |
| via chardev or netlink |
+-----------------------------------------------------------+
| daedalus-v4l2 userspace daemon (`daemon/`) |
| - takes bitstream blobs + per-slice controls |
| - drives FFmpeg parsers via dlopen (Option γ) |
| - dispatches per-block ops via daedalus-fourier |
| public API (daedalus_dispatch_*) |
| - posts decoded frames back to kernel module |
+-----------------------------------------------------------+
| daedalus-fourier kernel library (sibling project) |
| - exports include/daedalus.h public API |
| - per-kernel CPU NEON + opportunistic V3D QPU dispatch |
| - 9 closed cycles across VP9, AV1 CDEF, H.264 |
+-----------------------------------------------------------+
| V3D 7.1 (Mesa userspace v3dv) + ARM NEON (BCM2712) |
+-----------------------------------------------------------+
Why this architecture (Option B + γ + sibling)
Locked by user 2026-05-18 from 3 options in
daedalus-fourier/docs/phase8_scoping.md:
- Option B over A (userspace v4l2loopback): real
/dev/videoNN, proper DRM PRIME / dmabuf for browser zero-copy. - Option γ: dlopen FFmpeg as parser at runtime. No vendoring, fastest to v1.
- Sibling repo: per
project_consumer_targetconvention, V4L2-side work lives outside daedalus-fourier so the kernel-library has a clean API boundary.
Status
Initial scaffold only. See docs/architecture.md for the
deeper design and docs/roadmap.md for the
sub-phase breakdown.
Repo layout
kernel/— Linux kernel module (V4L2 device registration + ioctl handling + userspace chardev bridge). Out-of-tree.daemon/— userspace decoder daemon (linkslibdaedalus_core.afrom sibling daedalus-fourier; uses dlopen for FFmpeg parser).include/— shared headers between kernel and daemon.docs/— architecture + roadmap.
License
Kernel module: GPLv2 (required for kernel-tree compatibility). Userspace daemon: BSD-2-Clause (matches daedalus-fourier).