α-23 test (skip media_request_reinit): no change. HEVC still 06b2c5a0...
all-zero. Kernel printk still shows w=0 h=0 for libva.
Cumulative disproved mechanisms (iter17-iter19):
2. REINIT clears between S_EXT_CTRLS and QUEUE: DISPROVED (α-23)
3. Stale stack-local pointer: DISPROVED (α-21)
5. Silent partial failure via error_idx: DISPROVED (α-22)
1. request_fd mismatch: unlikely per strace evidence
Remaining:
4. ctrl_hdl mismatch — libva submits to one v4l2_ctrl_handler,
rkvdec reads from another.
iter20 candidate: kernel printk dumping &ctx->ctrl_hdl, per-ID
ctrl pointer, and *p_cur.p first bytes during rkvdec_hevc_run_preamble.
Comparing libva vs kdirect will pinpoint where the mismatch sits.
State at close: backend c1d4bb53... (iter15 stable). Fork tip 415688d.
5-codec anchors held. Diagnostic kernel 7.0-3 still running on fresnel.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
