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Final handoff doc: campaign closed at 5/5 PASS on 7.0-14 clean kernel

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Markus Fritsche
2026-05-14 16:52:18 +00:00
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PRE_COMPACT_HANDOFF.md
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# Pre-Compact Handoff — Session 2026-05-14 (updated post iter31)
# Pre-Compact Handoff — Session 2026-05-14 (FINAL post iter34)
Use this doc to resume the fresnel-fourier campaign after Claude context compaction.
Use this doc to resume the fresnel-fourier campaign after Claude context compaction. **Campaign is at full close state: 5/5 codecs PASS.**
## TL;DR (read first)
- **Bug 4 (H.264 keyframe-partial): FIXED iter25 α-25** — H.264 10F byte-equal to SW reference.
- **Bug 5 (HEVC libva all-zero / frame 2+ divergence): FULLY FIXED** — frame 1 via α-25, frames 2+ via iter31 α-29. HEVC 10F byte-equal to SW.
- **VP9**: unchanged (HW=SW byte-equal, no regression from α-29).
- **MPEG-2 / VP8**: untestable through libva on current kernel boot (pre-existing libva single-device profile-probe limitation; auto-select picks rkvdec which doesn't expose those profiles).
| Bug | Status | Fix |
|---|---|---|
| Bug 4 (H.264 keyframe-partial) | **FIXED** iter25 α-25 | rkvdec image_fmt pre-seed via synthetic SPS at CreateContext |
| Bug 5 (HEVC libva all-zero CAPTURE) | **FIXED** iter25 + iter31 | α-25 (image_fmt) + α-29 (slice_params.short_term_ref_pic_set_size from VAAPI st_rps_bits) |
| VP8 wrong output through libva | **FIXED** iter33 α-30 | prepend VP8 uncompressed frame header (10 kf / 3 inter) to OUTPUT |
| MPEG-2 HW differs from SW | **NOT A BUG** | hantro IDCT precision (≤1 LSB / ~67 px); libva==kdirect bit-exact |
| Kernel diagnostic printks | **CLEANED** iter32 + iter34 | 7.0-14 ship |
Final score on rkvdec-routed anchors: **3/3 PASS**. MPEG-2/VP8 path orthogonal to Bug 4/5.
| Codec | libva 10F sha | kdirect 10F sha | SW 10F sha | L==K | L==SW |
|---|---|---|---|---|---|
| H.264 | dd4f5f2d552c07bc | same | same | ✓ | ✓ |
| HEVC | 108f925bb6cbb6c9 | same | same | ✓ | ✓ |
| VP9 | cf35908ae0f9ab60 | same | same | ✓ | ✓ |
| VP8 | d3231e5b6c0ee10b | same | same | ✓ | ✓ |
| MPEG-2| 95c5905890c937d4 | same | 933b744134e47ba4 | ✓ | ~ |
**5/5 PASS** the libva-vs-kdirect bit-exact contract.
## Substrate state (where things live)
| Component | Location | Tip |
|---|---|---|
| Campaign repo (this) | `/home/mfritsche/src/fresnel-fourier/` | `c1f9738` on gitea master |
| Libva backend fork (noether) | `/home/mfritsche/src/libva-multiplanar/libva-v4l2-request-fourier/` | `23eb1bd` on gitea master |
| Campaign repo (this) | `/home/mfritsche/src/fresnel-fourier/` | `70ddbd6` on gitea master |
| Libva backend fork (noether) | `/home/mfritsche/src/libva-multiplanar/libva-v4l2-request-fourier/` | `7e0848d` on gitea master |
| Libva backend (fresnel deploy) | `/home/mfritsche/src/libva-v4l2-request-fourier/` | sync to gitea master, `ninja -C build` |
| Kernel source (boltzmann) | `~/src/kernel-agent-bootstrap/build/marfrit-packages/arch/linux-fresnel-fourier/` | pkgrel=10 with iter17/20/21/22/23/27/31 diag printks |
| Kernel running on fresnel | `linux-fresnel-fourier 7.0-10` | diagnostic build; revert to clean 7.0-N before any production work |
| Kernel source (boltzmann) | `~/src/kernel-agent-bootstrap/build/marfrit-packages/arch/linux-fresnel-fourier/` | pkgrel=14 clean (no diagnostic printks) |
| Kernel running on fresnel | `linux-fresnel-fourier 7.0-14` | clean shipping kernel |
| Test fixtures (fresnel) | `/home/mfritsche/fourier-test/bbb_*.{mp4,ts,webm}` | 5 codecs at 720p10s or 1080p30 |
| Anchors (fresnel) | `/tmp/iter31/{libva,sw}_{h264,hevc,vp9}_10f.yuv` | per-frame SHA match SW |
| Memory | `~/.claude/projects/-home-mfritsche-src-fresnel-fourier/memory/` | new: `feedback_va_st_rps_bits_is_slice_field.md` |
| Anchors (fresnel) | `/tmp/final/{L,K,S}_<codec>.yuv` | 10-frame YUV per codec per backend |
| Memory | `~/.claude/projects/-home-mfritsche-src-fresnel-fourier/memory/` | see entries below |
## Identity for gitea pushes
All `git.reauktion.de` interactions use `claude-noether` identity (per memory `feedback_gitea_as_claude_noether.md`). Backend remote URL: `ssh://gitea@git.reauktion.de.claude-noether/marfrit/libva-v4l2-request-fourier.git`.
## Backend commits delivered (chronological, this campaign)
## Device map on 7.0-14 (REVERSED from 7.0-13)
`/dev/video*` and `/dev/media*` numbers SHIFT between kernel boots based on probe order. On 7.0-14 (current):
| Driver | /dev/videoN | /dev/mediaN |
|---|---|---|
| rockchip-rga | video0 | n/a |
| rk3399-vpu-enc | video1 | (shared) |
| rk3399-vpu-dec (hantro) | **video2** | **media0** |
| rkvdec | **video3** | **media1** |
Always re-probe via `v4l2-ctl --info` + `media-ctl -p` before hardcoding paths.
## Backend commits delivered (chronological, this campaign day)
```
23eb1bd iter31 α-29: slice_params.short_term_ref_pic_set_size = picture->st_rps_bits ← Bug 5 remainder fix
68dbbdd iter30 DIAG: LIBVA_TS_SCALE env-gated timestamp multiplier (env-gated, no-op default)
0eca3ff iter29 DIAG: env-gated dump of HEVC slice_data trailing 80 bytes
6646b16 Revert iter28b DIAG (universal trim=40 broke IDR)
7e0848d iter33 α-30: prepend VP8 uncompressed frame header to OUTPUT buffer ← VP8 fix
bf3e3d8 iter33: extend VP8 DIAG to dump VAAPI probability struct directly (env-gated diag)
4b3c21b iter33 DIAG: env-gated dump of v4l2_ctrl_vp8_frame contents (env-gated diag)
23eb1bd iter31 α-29: slice_params.short_term_ref_pic_set_size = picture->st_rps_bits ← HEVC fix
68dbbdd iter30 DIAG: LIBVA_TS_SCALE env-gated timestamp multiplier (env-gated diag)
0eca3ff iter29 DIAG: env-gated dump of HEVC slice_data trailing 80 bytes (env-gated diag)
6646b16 Revert iter28b DIAG: trim=40 universal-trim broke IDR frame 1
cd286d9 iter28 α-28: bit_size = (slice_data_size - data_byte_offset) * 8 for HEVC
754be1d iter27 diag: env-gated VAAPI slice fields dump
719d813 iter27 α-27: populate slice_params.num_entry_point_offsets (no-op, rkvdec ignores)
66ef848 iter26 α-26: populate decode_params.short_term_ref_pic_set_size (mis-routed; rkvdec ignores)
d062fec iter25 α-25 fix: add FRAME_MBS_ONLY to H264 dummy SPS
db0b7f9 iter25 α-25: inject synthetic SPS before cap_pool_init to seed image_fmt ← Bug 4 + Bug 5 frame 1 fix
719d813 iter27 α-27: populate slice_params.num_entry_point_offsets (no-op)
66ef848 iter26 α-26: decode_params.short_term_ref_pic_set_size from VAAPI (mis-routed cosmetic)
d062fec iter25 α-25 fix: FRAME_MBS_ONLY flag for H264 dummy SPS
db0b7f9 iter25 α-25: inject synthetic SPS before cap_pool_init to seed image_fmt ← H264+HEVC frame 1 fix
```
## Campaign repo commits delivered
The load-bearing commits are `db0b7f9 + d062fec` (α-25), `23eb1bd` (α-29), `7e0848d` (α-30). The DIAG commits are env-gated and inactive by default.
## Campaign repo commits delivered (today's arc)
```
70ddbd6 iter34 close: kernel 7.0-14 CLEAN ship — 5/5 codecs PASS
cd2d077 iter33: MPEG-2 closed (libva==kdirect bit-exact) — 5/5 codecs PASS
51eee19 iter33 α-30 close: VP8 FIXED — 4/5 codecs PASS
acacf3d iter32 close: kernel substrate cleanup landed → 7.0-11 SHIPPING
85cc178 Update campaign session doc: full-day arc closes at 3/3 PASS
fde8a25 Update handoff doc: HEVC Bug 5 fully fixed (3/3 PASS)
c1f9738 iter31 α-29 close: HEVC Bug 5 remainder FIXED — 3/3 PASS
422ecaf Add pre-compact handoff doc for session resumption
c15fc6c iter28b DIAG documented: universal trim=40 breaks IDR (reverted)
8b17bf7 Final session summary: H264 + VP9 + HEVC frame 1 byte-equal to SW
02c4192 iter27/28: probe HEVC frame 2+ divergence; α-27/α-28 no-op
bf67900 iter20-26: kernel-side root-cause localization, α-25/α-26 fix Bug 4, partial Bug 5
…earlier in day:
c15fc6c, 8b17bf7, 02c4192, bf67900 (iter20-28 chain)
```
Phase docs (chronological): `phase4_iter21_plan.md`, `phase4_iter22_plan.md`, `phase8_iteration20_close.md` … `phase8_iteration27_close.md`, `phase8_iteration31_close.md`, `CAMPAIGN_SESSION_2026_05_14.md`.
## How to verify the current state
Run on fresnel after `git pull` + `ninja -C build` in `~/src/libva-v4l2-request-fourier`:
Run on fresnel (post-7.0-14 boot, devices: rkvdec /dev/video3+/dev/media1, hantro /dev/video2+/dev/media0):
```bash
for codec in h264:bbb_1080p30_h264.mp4 hevc:bbb_720p10s_hevc.mp4 vp9:bbb_720p10s_vp9.webm ; do
name="${codec%%:*}"; fixture="${codec#*:}"
for codec in h264:bbb_1080p30_h264.mp4:rk hevc:bbb_720p10s_hevc.mp4:rk vp9:bbb_720p10s_vp9.webm:rk vp8:bbb_720p10s_vp8.webm:ha mpeg2:bbb_720p10s_mpeg2.ts:ha; do
name="${codec%%:*}"; rest="${codec#*:}"; fixture="${rest%:*}"; dev="${rest##*:}"
if [ "$dev" = "rk" ]; then V=/dev/video3; M=/dev/media1
else V=/dev/video2; M=/dev/media0; fi
env LIBVA_DRIVER_NAME=v4l2_request \
LIBVA_DRIVERS_PATH=/home/mfritsche/src/libva-v4l2-request-fourier/build/src \
LIBVA_V4L2_REQUEST_VIDEO_PATH=/dev/video1 \
LIBVA_V4L2_REQUEST_MEDIA_PATH=/dev/media0 \
LIBVA_V4L2_REQUEST_VIDEO_PATH=$V LIBVA_V4L2_REQUEST_MEDIA_PATH=$M \
ffmpeg -hide_banner -loglevel error -y \
-hwaccel vaapi -hwaccel_output_format vaapi \
-i "/home/mfritsche/fourier-test/$fixture" \
-vf "hwdownload,format=nv12" -frames:v 10 \
-f rawvideo -pix_fmt nv12 "/tmp/libva_${name}.yuv"
ffmpeg -hide_banner -loglevel error -y \
-i "/home/mfritsche/fourier-test/$fixture" \
-frames:v 10 -f rawvideo -pix_fmt nv12 "/tmp/sw_${name}.yuv"
if cmp -s "/tmp/libva_${name}.yuv" "/tmp/sw_${name}.yuv"; then
echo "$name: PASS"
else
echo "$name: FAIL"
fi
-f rawvideo -pix_fmt nv12 "/tmp/L_${name}.yuv"
ffmpeg -hide_banner -loglevel error -y -hwaccel v4l2request -hwaccel_output_format drm_prime \
-i "/home/mfritsche/fourier-test/$fixture" -vf "hwdownload,format=nv12" \
-frames:v 10 -f rawvideo -pix_fmt nv12 "/tmp/K_${name}.yuv"
L=$(sha256sum "/tmp/L_${name}.yuv" | cut -c1-16)
K=$(sha256sum "/tmp/K_${name}.yuv" | cut -c1-16)
[ "$L" = "$K" ] && echo "$name: PASS" || echo "$name: FAIL"
done
```
Expect: 3× PASS.
Expect: 5× PASS.
## Root cause summary
**Bug 4 (H.264) + Bug 5 frame 1 (HEVC IDR)**: `rkvdec_s_ctrl` returned -EBUSY when first SPS set tried to reset `image_fmt` on a busy CAPTURE queue. libva pre-allocated CAPTURE in CreateContext (iter5b-β design) before per-frame S_EXT_CTRLS. Fix: synthetic SPS injection pre-cap_pool_init so reset succeeds while queue empty. Source: `db0b7f9` + `d062fec`.
**Bug 4 + Bug 5 frame 1 (iter25 α-25)**: `rkvdec_s_ctrl` returns -EBUSY when first SPS triggers image_fmt reset on busy CAPTURE queue. libva pre-allocated 24 CAPTURE buffers at CreateContext (iter5b-β) before per-frame S_EXT_CTRLS. Fix: inject synthetic SPS at CreateContext, pre-cap_pool_init, while CAPTURE is empty.
**Bug 5 frame 2+ (HEVC non-IDR)**: libva backend set `slice_params->short_term_ref_pic_set_size = 0` (with stale "VAAPI doesn't expose" comment). rkvdec's `assemble_sw_rps` (rkvdec-hevc.c:386-389) reads this field to compute long-term-RPS bit offset; when zero AND `num_short_term_ref_pic_sets <= 1`, falls back to 0 → HW entropy decoder consumes slice-header bits as long-term-RPS → garbage state for every non-IDR slice. IDR is gated out (`!IDR_PIC` flag) so frame 1 unaffected. Fix: `slice_params->short_term_ref_pic_set_size = picture->st_rps_bits` (VAAPI doc says st_rps_bits IS the slice-header bit count — α-26 mis-routed it into decode_params with same field name but different semantics). Source: `23eb1bd`.
**Bug 5 frame 2+ (iter31 α-29)**: libva backend set `slice_params->short_term_ref_pic_set_size = 0` (stale "VAAPI doesn't expose" comment). rkvdec's `assemble_sw_rps` (rkvdec-hevc.c:386-389) reads this; when zero with `num_short_term_ref_pic_sets <= 1`, falls back to 0 → entropy decoder consumes slice-header bits as long-term-RPS → garbage for every non-IDR slice. IDR is gated by `!IDR_PIC` so frame 1 was unaffected. Fix: `slice_params->short_term_ref_pic_set_size = picture->st_rps_bits` (VAAPI's field IS the slice-header bit count, per va_dec_hevc.h doc). α-26 had mis-routed this value into decode_params (same field name, different V4L2 semantics).
## Open items (deferred)
**VP8 (iter33 α-30)**: ffmpeg-vaapi strips the VP8 uncompressed frame header (3 bytes interframe / 10 bytes keyframe) before submitting via VAAPI. ffmpeg-v4l2request keeps it. Hantro hard-codes `first_part_offset = V4L2_VP8_FRAME_IS_KEY_FRAME(hdr) ? 10 : 3` and uses it for both `mb_offset_bits` and `dct_part_offset`. Without the prepended header in libva's OUTPUT, hantro's offset arithmetic lands inside the compressed bitstream and the entropy decoder produces garbage. Fix: in codec_store_buffer, prepend `header_size` zero bytes to OUTPUT for VP8 profile (hantro skips these bytes for actual parsing, uses ctrl-struct values).
### 1. Kernel substrate cleanup
## Open items (low priority, no blockers)
`linux-fresnel-fourier 7.0-10` has 5+ accumulated `pr_info` diagnostic patches in:
- `drivers/media/v4l2-core/v4l2-ctrls-request.c` (iter21-24 setup/clone/loop traces)
- `drivers/media/platform/rockchip/rkvdec/rkvdec-hevc.c` (iter17/20/27/31 SPS/DP/slice dumps)
1. **Backend env-gated diagnostics cleanup** — `LIBVA_HEVC_DUMP_SLICE_TAIL` (iter29), `LIBVA_TS_SCALE` (iter30), `LIBVA_VP8_DUMP_FRAME` (iter33) are env-gated and inactive by default. Leave for future regression debugging or clean up. Low priority.
Before any production work, revert to clean 7.0-N (i.e., apply only the 3 PBP DTS patches + RFC v2 fence series, without diagnostics). Bump pkgrel to 11 and ship clean.
2. **α-26 cosmetic revert** — `decode_params->short_term_ref_pic_set_size = picture->st_rps_bits` was mis-routed (rkvdec doesn't use that field). Could revert to 0. Cosmetic; no behavior change.
### 2. MPEG-2 / VP8 untestable through libva on current kernel boot
3. **Libva multi-device probe** — currently `find_codec_device` picks ONE device per session, requiring `LIBVA_V4L2_REQUEST_VIDEO_PATH` override to access both rkvdec (H264/HEVC/VP9) and hantro (VP8/MPEG-2) within one workflow. Architectural change in `src/request.c::find_codec_device` (~200-400 LOC). Design judgment from user welcome.
Libva backend's `find_codec_device` (`src/request.c:427`) selects ONE device for the entire session. On RK3399 with both rkvdec (`/dev/media0`+`/dev/video1`) and hantro (`/dev/media1`+`/dev/video2`+`/dev/video3`), the backend picks rkvdec — which exposes H264/HEVC/VP9 only.
## Memory entries (full set, this campaign)
Override with `LIBVA_V4L2_REQUEST_VIDEO_PATH=/dev/video3 LIBVA_V4L2_REQUEST_MEDIA_PATH=/dev/media1` to force hantro for MPEG-2/VP8 testing. But that disables H264/HEVC/VP9 simultaneously, and the unconditional HEVC DECODE_MODE/START_CODE controls libva sets at CreateContext (`context.c:343-379`) fail on hantro with `Unable to set control(s): Invalid argument` — pre-existing, orthogonal to Bug 4/5.
Fix would require either:
- Libva backend multi-device probe + per-codec dispatch (~200-400 LOC, called out in `phase0_findings_iter7.md`).
- Conditional codec-init controls (skip controls hantro doesn't support).
### 3. iter29/iter30 env-gated diagnostics in backend
`LIBVA_HEVC_DUMP_SLICE_TAIL=1` and `LIBVA_TS_SCALE=N` are present in the backend but env-gated (no behavior change without env set). Could clean up to keep ship-ready source minimal. Or leave them — useful for future regression debugging. Low priority either way.
### 4. α-26 dead-code
`decode_params->short_term_ref_pic_set_size = picture->st_rps_bits` was mis-routed (right value to wrong field). rkvdec doesn't use decode_params's same-named field. Could revert α-26 to set 0 (which is correct per V4L2 spec when SPS-defined RPS bit count is unknown). Cosmetic.
## Memory entries (this session arc)
- **New**: `feedback_va_st_rps_bits_is_slice_field.md` — VAAPI's `picture->st_rps_bits` belongs in `slice_params`, not `decode_params`. Same field name, different semantics.
- **Updated**: `feedback_rkvdec_image_fmt_pre_seed.md` — note Bug 5 remainder is now fixed (not via image_fmt; see new entry).
- **Updated**: `feedback_libva_byte_correct_kernel_bug.md` — FULLY OVERTURNED (both Bug 4 and Bug 5 are libva-side fixes).
- `feedback_rkvdec_image_fmt_pre_seed.md` — α-25 (Bug 4 + Bug 5 frame 1)
- `feedback_va_st_rps_bits_is_slice_field.md` — α-29 (Bug 5 frame 2+)
- `feedback_vaapi_strips_vp8_uncompressed_header.md` — α-30 (VP8)
- `feedback_libva_byte_correct_kernel_bug.md` — FULLY OVERTURNED (both Bug 4 + Bug 5 are libva-side fixes)
- `reference_fresnel_kernel_substrate.md` — 7.0-14 clean, device-enumeration caveat noted
- MEMORY.md index updated
## Key commands quickreference
@@ -131,38 +146,38 @@ Fix would require either:
# Sync backend on fresnel + rebuild
ssh fresnel 'cd ~/src/libva-v4l2-request-fourier && git fetch && git reset --hard origin/master && ninja -C build'
# 3-codec smoke (above script). Each codec ~5s.
# Identify which video device is rkvdec vs hantro after a fresh boot
ssh fresnel 'for v in /dev/video*; do v4l2-ctl -d $v --info 2>/dev/null | grep -E "^Card type" | head -1 | awk -v dev=$v "{print dev,\$0}"; done'
# Run libva HEVC + capture rkvdec kernel iter27/31 printk
ssh fresnel 'sudo dmesg -C; env LIBVA_DRIVER_NAME=v4l2_request \
# 5-codec smoke (above script)
# Run libva HEVC (rkvdec is currently /dev/video3 on 7.0-14)
ssh fresnel 'env LIBVA_DRIVER_NAME=v4l2_request \
LIBVA_DRIVERS_PATH=/home/mfritsche/src/libva-v4l2-request-fourier/build/src \
LIBVA_V4L2_REQUEST_VIDEO_PATH=/dev/video1 \
LIBVA_V4L2_REQUEST_MEDIA_PATH=/dev/media0 \
LIBVA_V4L2_REQUEST_VIDEO_PATH=/dev/video3 LIBVA_V4L2_REQUEST_MEDIA_PATH=/dev/media1 \
ffmpeg -hide_banner -loglevel error -y -hwaccel vaapi -hwaccel_output_format vaapi \
-i /home/mfritsche/fourier-test/bbb_720p10s_hevc.mp4 \
-vf "hwdownload,format=nv12" -frames:v 3 -f rawvideo -pix_fmt nv12 /tmp/x.yuv;
sudo dmesg | grep -E "rkvdec_iter2[07]|rkvdec_iter31"'
-vf "hwdownload,format=nv12" -frames:v 10 -f rawvideo -pix_fmt nv12 /tmp/x.yuv'
# kdirect (ffmpeg-v4l2request) reference
ssh fresnel 'ffmpeg -hide_banner -loglevel error -y -hwaccel v4l2request \
# kdirect reference (works for any codec; hwaccel auto-routes)
ssh fresnel 'ffmpeg -hide_banner -loglevel error -y -hwaccel v4l2request -hwaccel_output_format drm_prime \
-i /home/mfritsche/fourier-test/bbb_720p10s_hevc.mp4 \
-frames:v 10 -f null -' # decode-only, dmesg has iter27/31 entries
-vf "hwdownload,format=nv12" -frames:v 10 -f rawvideo -pix_fmt nv12 /tmp/y.yuv'
# Reboot fresnel (sddm autologin reseats mfritsche per /etc/sddm.conf.d/20-autologin.conf)
# Reboot fresnel (sddm autologin reseats mfritsche)
ssh fresnel 'sudo systemctl reboot'; sleep 60
```
## What's safe to do without user confirmation
## Safe vs needs-confirmation actions
- Read/grep on noether, boltzmann, fresnel.
- Push to gitea (claude-noether identity).
- Reboot fresnel (sddm autologin restores session).
- Build kernel on boltzmann via `makepkg -e --noconfirm` in `~/src/kernel-agent-bootstrap/build/marfrit-packages/arch/linux-fresnel-fourier/`.
- Deploy kernel via `scp` + `sudo pacman -U`.
- Run ffmpeg/cmp tests on fresnel.
**Safe (no confirmation needed)**:
- Read/grep on noether, boltzmann, fresnel
- Push to gitea (claude-noether identity)
- Reboot fresnel (sddm autologin restores session)
- Build kernel on boltzmann via `makepkg -ef --skipinteg --noconfirm`
- Deploy kernel via `scp` + `sudo pacman -U`
- Run ffmpeg/cmp tests on fresnel
## What needs user confirmation
- Significant rebuild (~25-30 min CPU time on boltzmann, e.g., ffmpeg or fresh kernel build).
- Reverting kernel-substrate diagnostics to ship a clean kernel (mechanical but heavy).
- Architectural change to libva multi-device probe (Item 2) — affects libva backend design.
**Needs confirmation**:
- Significant rebuild (~25-30 min CPU on boltzmann, e.g. ffmpeg full rebuild or fresh kernel build)
- Architectural changes to libva multi-device probe (item 3 above) — affects backend design