Fixes the rkvdec_hevc_prepare_hw_st_rps out-of-bounds kernel OOPS that
blocked HEVC decode on ampere (RK3588) per
marfrit/libva-v4l2-request-fourier#3 and ampere-fourier iter1 close.
Mechanism (Phase 5 amendment to issue body):
The new EXT_SPS controls are registered as V4L2_CTRL_FLAG_DYNAMIC_ARRAY
in vdpu38x_hevc_ctrl_descs (rkvdec.c:279/284) with cfg.dims = { 65 }.
The v4l2-ctrl framework init-allocates 1 zeroed element (ctrls-core.c:2116).
When num_short_term_ref_pic_sets > 1, rkvdec_hevc_prepare_hw_st_rps
(rkvdec-hevc-common.c:393-405) iterates idx 0..N-1 and overruns the
1-element kernel allocation. Submitting an N-element dynamic-array
control via S_EXT_CTRLS extends the framework allocation.
Userspace fix:
- VIDIOC_QUERY_EXT_CTRL probe at first HEVC CreateContext sets
driver_data->has_ext_sps_rps (true on VDPU381/383, false on legacy
RK3399 — control unregistered there, so fresnel iter38 5/5 + iter39
sub-profile paths are byte-identical to pre-iter2).
- When set, h265_set_controls appends EXT_SPS_ST_RPS + _LT_RPS as
calloc'd zero arrays, sized by VAAPI's count fields and capped at
H.265 §7.4.3.2 spec maxima (ST 64, LT 32). Min 1 (kernel rejects 0).
- Free post-S_EXT_CTRLS.
Decode correctness scope:
VAAPI does NOT expose per-set st_ref_pic_set syntax elements
(delta_idx_minus1, delta_rps_sign, etc.) — confirmed in va_dec_hevc.h.
All-zero entries give empty inter-pred RPS per set, which is correct
for IDR-only streams and incorrect for streams with inter-pred RPS
dependence. iter2 acceptance: stop the OOPS. Decode-correctness for
inter-RPS content is a known follow-up requiring either bitstream-snoop
or SPS-passthrough via a new VAAPI extension.
Files:
- include/hevc-ctrls.h: #ifndef-guarded fallback definitions for
V4L2_CID_STATELESS_HEVC_EXT_SPS_{ST,LT}_RPS + structs (ampere host
is on linux-api-headers 6.19-1; the new CIDs land in 7.0).
- src/request.h: driver_data->has_ext_sps_rps (persists for driver
lifetime; gated solely by HEVC code path so cross-codec leakage
impossible).
- src/context.c: probe at HEVC CreateContext via v4l2_query_ext_ctrl.
- src/h265.c: controls[5] → controls[7]; #include <hevc-ctrls.h>
(replaces <linux/v4l2-controls.h>) for forward UAPI compatibility.
Compile-tested on boltzmann (aarch64 native, gcc 15.2.1): clean .so,
0 new warnings. Fresnel cross-device safety: legacy RK3399 rkvdec_ctrl
table omits the CIDs; probe returns false; new code path never executes.
iter39 sub-profile work (commits 662f887 + 8746690) is preserved
in-tree; iter2 is a forward-compatible additive change.
Refs:
marfrit/libva-v4l2-request-fourier#3
ampere-fourier/iter1_close.md HEVC blocker
ampere-fourier/iter2_phase0_findings.md
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
claude-noether
f61f736380