marfrit d87c940788 iter4 Phase 7: criterion 1+2+3 PASS, criterion 4+5 FAIL — three bug classes identified ...

Verification on linux-fresnel-fourier 7.0-1:

PASS:
- Criterion 1: vainfo enumerates VAProfileVP9Profile0 via auto-detect.
- Criterion 2: vaCreateConfig SUCCESS (implicit).
- Criterion 3: ffmpeg-vaapi VP9 5-frame decode exit 0 at 0.307x, no
  ioctl errors.

FAIL — three distinguishable bug classes:

Bug 1 (VP9-specific, my Clause 6 parser):
  Strace of frame-1 keyframe FRAME control vs Phase 3 anchor:
  - byte 8 (lf.flags): mine=0x01 (DELTA_ENABLED only) vs ref=0x03
    (ENABLED|UPDATE).
  - byte 16 (base_q_idx): mine=0x41 (65) vs ref=0x2e (46).
  - byte 17 (delta_q_y_dc): mine=8 vs ref=0.
  Bit-trace shows my parser is 2 bits ahead of correct position by
  the time it reaches lf_delta_enabled. Fix path: faithful port of
  FFmpeg vp9.c::decode_frame_header.

Bug 2 (substrate-wide, cap_pool readback):
  Constant RGB(0, 0x4c, 0) "0x4c gray" pattern across all codecs
  (VP9, HEVC, MPEG-2, VP8). H.264 keyframe DOES read correctly with
  real RGB(0, 0xe3, 0) content; H.264 inter frames revert to 0x4c.
  Kernel decode succeeds (Phase 3 strace + ffmpeg-v4l2request
  standalone confirm). libva readback returns cap_pool init scratch.
  Sibling of iter3 dma_resv blocker but with different signature
  (constant 0x4c instead of all-zero 0x00).

Bug 3 (hantro UAPI drift):
  MPEG-2 + VP8 produce kernel "Unable to set control(s): Invalid
  argument" errors. UAPI struct sizes/fields likely shifted between
  6.19.9 and 7.0 (sibling of Phase 3 VP9 struct-size correction
  144/1947 -> 168/2040).

Three loopback options proposed (decision pending user):
- A: VP9-only fix (Clause 6 parser); accept Bug 2/3 as substrate
     pre-existing; criterion 4 transitive-only per iter3.
- B: Full loopback covering all 3 bugs; possibly requires kernel
     patches (vb2_dma_resv RFC v2).
- C: Phase 0 reset; substrate is the primary issue; pause iter4.

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

2026-05-10 07:20:51 +00:00

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