marfrit
a4e7d8ab90
panvk-bifrost campaigns (r1..r4 Vulkan compositor + r5.video1 Vulkan
video decode) shipped before this repo existed; the deliverable
patches live in marfrit-packages, but the reasoning chain, phase docs,
and source-state evidence lived only in local working trees on the
development host.
This retrofit imports:
- mesa-panvk-bifrost/ — r1..r4 era phase docs (iter1..iter18)
(libmali stub blobs at iter18/blob/ excluded
— 109MB of RE artifacts replaced with a README
pointer)
- mesa-panvk-bifrost-video/ — sibling campaign phase docs + probe
- evidence/ — frozen .tgz source snapshots at each milestone
(basis for the 0005 patch diff generation)
Future iterations should branch off here from day one, so each iter is
a commit rather than a snapshot. See [[feedback-session-local-process-pins]]
for the process drift this retrofit closes.
Total: 1.9 MB across 124 files.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
72 lines
3.6 KiB
Markdown
72 lines
3.6 KiB
Markdown
# Iteration 6 close — GREEN
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Closed **2026-05-19**, same session as iter1–5.
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## Locked question
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(From [phase0_findings_iter6.md](phase0_findings_iter6.md))
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> Depth-tested multi-draw: 128×128 RGBA8 + D32_SFLOAT depth attachment, large red triangle at z=0.7 + small green triangle at z=0.3 fully inside it, depth test selects green in overlap.
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## Result: GREEN
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7/7 runs PASS (1 baseline + 1 validation + 5 stability). All five verification pixels correct. Deterministic across runs: red=3850, green=1352, clear=11182, other=0. No GPU faults, no validation warnings.
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Evidence: [`phase0_evidence/iter6_depth_run.txt`](phase0_evidence/iter6_depth_run.txt).
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## What the close tells us
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All seven hypotheses in [phase0_findings_iter6.md](phase0_findings_iter6.md) — **none materialized.**
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- D32_SFLOAT depth attachment works (optimalTilingFeatures=0xd601 includes DEPTH_STENCIL_ATTACHMENT_BIT)
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- Depth-stencil image creation + layout + image view all clean
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- Depth test plumbing wires through to tile descriptors correctly
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- Depth writes back to depth attachment correctly (otherwise overlap region would be all-red or all-green)
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- Multi-draw in one render pass: both `vkCmdDraw` calls produced their triangles
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- z-coord from vertex shader propagates through to depth test
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- 128×128 tile binning (64 tiles, 4× larger than iter3) clean
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Coverage accounting clean:
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- Triangle A (red, NDC area 1.28 / 4 sq NDC = 32% expected) → 5202 non-clear pixels (3850 red + 1352 green) ≈ expected
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- Triangle B (green, NDC area 0.32 / 4 = 8% expected) → 1352 ≈ expected
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- "other" count = 0: no banding, no z-fighting artifacts, no interp errors at edges
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## iter6 in-tree artifacts
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- [`iter6/probe_depth.c`](iter6/probe_depth.c) — depth probe
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- [`iter6/probe_depth.vert`](iter6/probe_depth.vert) — vec3 pos + color
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- [`iter6/probe_depth.frag`](iter6/probe_depth.frag) — pass-through
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- [`iter6/Makefile`](iter6/Makefile)
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## Cumulative state — six iters, ~40 runs, zero driver failures
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PanVk-Bifrost on Mali-G52 r1 v7 has now been proven functional for:
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| Surface | Works |
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| Compute pipeline + dispatch + storage buffer | ✓ iter1 |
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| Image clear + transfer ops + tile decode | ✓ iter2 |
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| Graphics pipeline + dynamic rendering + tile binner | ✓ iter3 |
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| Sampled texture + COMBINED_IMAGE_SAMPLER + texelFetch | ✓ iter4 |
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| Vertex buffer + UBO + vertex-stage descriptors + varying interp | ✓ iter5 |
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| Depth attachment + depth test + multi-draw | ✓ iter6 |
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The "PAN_I_WANT_A_BROKEN_VULKAN_DRIVER" gate continues to look defensive, not load-bearing.
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## Next iter — iter7 lock proposal
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**Jump to a real off-the-shelf app: `vkcube` on ohm with the live Wayland session.**
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Justifications:
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- vkcube is the Vulkan reference demo — rotating textured cube, classic workload.
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- It exercises **continuous rendering** (many submissions in a row) which our static probes haven't tested.
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- It uses **VK_KHR_swapchain** (WSI) — first time we test the swapchain path.
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- It uses **Wayland surface** on a live compositor (Plasma) — first time we test KHR_wayland_surface.
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- If it works, that's massive validation toward TuxRacer-via-Zink.
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- If it crashes, that's the first interesting bug, and we have a known-reference reproducer.
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iter7 question:
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> **Run `vkcube --c 120` (120 frames) on ohm with `PAN_I_WANT_A_BROKEN_VULKAN_DRIVER=1`, `XDG_RUNTIME_DIR=/run/user/$(id -u)`, `WAYLAND_DISPLAY=wayland-0` (or detected). Verify: process exits 0, no GPU faults in dmesg, no kernel-side panfrost errors. Operator visual confirmation of correct cube rendering optional (PineTab2 is visible to operator).**
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Pacing per the 8-phase loop. Opening iter7 immediately.
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