TL;DR section at the top covers:
- What libva is (standard userspace shim, backends per hardware,
what v4l2_request is in this lineage)
- Why firefox-fourier exists (Firefox 150 RDD sandbox blocks
/dev/media* + linux/media.h ioctls; the ~50-line patch opens
just what V4L2-stateless decoders need)
- Sister fourier-series campaigns: kwin-fourier (compositor /
scanout-plane fixes) + chromium-fourier (Chromium VAAPI on aarch64
+ GL-stack workarounds for Mali-G52/Panfrost)
Skim-friendly intro for new readers; the rest of the README stays
the campaign-discipline detail.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Phase 1 locked F (Firefox RDD sandbox verify-by-patch) and A (frame-11
EINVAL diagnose) running in parallel on a single firefox-fourier build.
Track F: GREEN. Patched Firefox 150.0.1 (firefox-fourier, pkgrel=1.1)
launches on ohm WITHOUT MOZ_DISABLE_RDD_SANDBOX=1 and engages our
libva-v4l2-request backend end-to-end. Three patches needed (Phase 2
identified one and deferred two):
- Broker policy (SandboxBrokerPolicyFactory.cpp): allow /dev/media*,
extend cap-filter to admit stateless decoders that lack M2M caps.
- Seccomp policy (SandboxFilter.cpp): allow ioctl magic byte '|'
for <linux/media.h> request-API ioctls.
- Driver (media.c): replace select() with poll() — Mozilla's RDD
seccomp common policy admits poll/ppoll/epoll_* but not
select/pselect6. Driver-side fix preferred; smaller surface,
portable across sandbox policies, and poll() is the modern API.
Track A: REPRODUCES + DIAGNOSED. Frame-11 EINVAL fires deterministically
on a single-slice P-frame (slice_type=0, frame_num=5, post-IDR) — the
exact iter1/iter2 carryover signature, confirming it isn't environmental.
Y2 instrumentation (in v4l2_ioctl_controls) now logs num_controls /
error_idx / per-control id+size on EINVAL. Sizes match kernel UAPI;
error_idx == num_controls is the kernel's "all bad / no specific control"
sentinel — it's a request-level rejection, not a single-field violation.
Fix is iter4's lock; rig + Y2 in place for fast iter4 turnaround.
Build infrastructure introduced: firefox-fourier LXD container on
boltzmann (RK3588 aarch64, persistent, ssh -J boltzmann
builder@firefox-fourier). Upstream Arch x86_64 wasi packages installed
to work around 4-year-stale ALARM versions. PGO generation crashes at
exit (LXC has no display); obj/dist/ tarball used as the deployable
artifact instead of the pacman package.
Phase 6 surprises captured in phase6_iter3_findings.md: malformed
first-cut patch (descriptive vs numeric hunk headers), --enable-v4l2
isn't a Mozilla 150 flag (auto-set on aarch64+GTK), Mozilla 2025 PGP
key rotation, ALARM-stale wasi, onnxruntime missing in ALARM, and the
"no tricks" lesson (revert workarounds first when redirected).
Carries to iter4 substrate: Track A fix is the natural lock; mpv
libplacebo --vo=gpu segfault stays as separate iter4 candidate.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Single-question campaign — make multi-planar libva accepted by VA-API
consumers on Rockchip hantro RK3568 (PineTab2/ohm first iteration).
Backend only, success criterion is boolean correctness, performance
deferred. Substrate carried over from libva-v4l2-request-fourier
STUDY.md (commit e0acc33 in the fork) plus locked decisions from the
2026-05-04 setup exchange.
Fork lives as a subdirectory: libva-v4l2-request-fourier/ (separate
git repo, origin marfrit/libva-v4l2-request-fourier, upstream
bootlin/libva-v4l2-request).
Empty Gitea repo created at git.reauktion.de/marfrit/libva-multiplanar;
local origin remote set, no push yet (per operator instruction —
wait for publish-worthy state).
claude-noether
marfrit