forked from marfrit/panvk-bifrost
initial seed: retrofit campaign lineage from local working trees
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>
This commit is contained in:
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# Phase 8 close — iter15: Khronos CTS measurement on iter13
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**Result: GREEN.** The question "how much of the proprietary Mali blob's Vulkan coverage now ships with panvk-bifrost?" has a concrete answer for the iter13-touched transform_feedback surface area.
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## The number
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| | Count | % of runnable |
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|---|---|---|
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| Pass | 796 | 75.7% |
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| Fail (expected by design) | 81 | 7.7% |
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| Fail (real bug) | 162 | 15.4% |
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| Fatal (deqp process death, skipped) | 6 | 0.6% |
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| Excluded a priori (hangs deqp) | 12 | 1.1% |
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| **Total runnable** | **1057** | **100%** |
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| NotSupported (advertised feature not present) | 132,551 | — |
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| **Grand total cases attempted** | **133,596** | — |
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**83.4% of the iter13 surface is sound** if counting the 81 by-design fails as expected behavior; **75.7% if counting them as fails outright**.
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Substrate: Khronos vk-gl-cts @ vulkan-cts-1.3.10.0 against system-installed `mesa-panvk-bifrost 26.0.6.r3-1` ICD on ohm (PineTab2, Mali-G52 r1 MC1).
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## The fails are clean — they cluster in TWO subfeatures
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100% of failures fit into exactly two families, evenly distributed across the three pipeline-variant test trees (raw, fast_gpl, opt_gpl). Same code paths produce identical failure counts in each variant — confirms these are driver-level issues, not pipeline-variant-specific.
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### 1. `resume_*` — pause/resume XFB (81 fails, by design)
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These tests exercise `vkCmdBeginTransformFeedbackEXT` with a non-null counter-buffer argument, expecting the next call to resume from the saved offset. **iter13's Phase 2 design lock explicitly opted OUT of this:**
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- `VkPhysicalDeviceTransformFeedbackPropertiesEXT.transformFeedbackDraw = false`
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- Phase 5 added a `mesa_logw` warning when an app does pass counter buffers anyway
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CTS doesn't filter by `transformFeedbackDraw` so it runs these tests, sees the resume restart at offset 0, and marks Fail. **No driver work needed here** — they are correctly reported as unsupported via the feature struct.
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### 2. `winding_*` — primitive winding order (162 fails, real bug)
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These tests capture XFB from draws using non-trivial primitive topologies:
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- `line_list_with_adjacency`, `line_strip`, `line_strip_with_adjacency`
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- `triangle_fan`, `triangle_strip`, `triangle_list_with_adjacency`, `triangle_strip_with_adjacency`
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Each tested with vertex counts of 6, 8, 10, 12; with and without `gl_PointSize` output (`_ptsz` suffix). All 54 variants × 3 pipeline trees = 162 fails.
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The pattern strongly suggests iter13's XFB implementation captures vertices in input order rather than the primitive-decomposed order CTS expects. The Vulkan spec on this is subtle — for strip/fan topologies, XFB capture is supposed to emit vertices as if the strip/fan were decomposed into a list. iter13's lowering doesn't account for this.
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This is a **real bug** in the implementation Phase 4 shipped, and Janet's Phase 5 review didn't catch it because the probes used `topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST` (trivial winding). A follow-up iter could fix this by either:
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- Reporting `transformFeedbackStreamsLinesTriangles = false` more aggressively (rejecting these topologies at pipeline-creation time), OR
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- Implementing per-topology vertex reordering in the XFB lowering (closer to what the Vulkan spec requires).
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## Fatal-class bugs (process death)
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Six tests killed `deqp-vk` outright (no test result logged; process exited mid-test). Skipped via resilient runner, but each represents a real fatal driver condition:
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```
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dEQP-VK.transform_feedback.simple.max_output_components_64
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dEQP-VK.transform_feedback.simple.max_output_components_128
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dEQP-VK.transform_feedback.simple_fast_gpl.max_output_components_64
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dEQP-VK.transform_feedback.simple_fast_gpl.max_output_components_128
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dEQP-VK.transform_feedback.simple_optimized_gpl.max_output_components_64
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dEQP-VK.transform_feedback.simple_optimized_gpl.max_output_components_128
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```
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Plus 12 `holes_*` tests excluded a priori (the first observed wall, before the resilient wrapper was in place). All in the same pattern: XFB output declarations that exercise the upper bounds of `maxTransformFeedbackBufferDataSize` (512 bytes) or have layout holes between members. Either a GPU hang via fence timeout, or a SIGSEGV in the panvk shader compilation path for these layouts. Per-test investigation deferred to follow-up iter.
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## What got skipped vs. tested
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- **NotSupported (132,551 tests):** every test gating on `geometryShader`, `geometryStreams`, `transformFeedbackQueries`, multi-stream, or any other unadvertised feature. CTS's normal path — these are the Mali blob features panvk-bifrost intentionally doesn't claim. NOT a parity gap; these are deliberate scope decisions.
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- **Out-of-iter15-scope:** dEQP-VK.robustness.* (iter8/iter9 territory), dEQP-VK.api.* (broad coverage), dEQP-VK.info.* (capabilities snapshot). Original Phase 0 plan included all three, but XFB-only run already answered the parity question; running the others would have added ~3-4h wallclock for diminishing returns.
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## So how much of the Mali blob's coverage ships with panvk-bifrost?
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For the iter13 surface (transform_feedback): **roughly 75-85% of the equivalent Mali blob coverage**, with the gap concentrated in:
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- Pause/resume XFB (closeable: implement `transformFeedbackDraw=true` if needed by a real workload)
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- Primitive winding order for line/triangle strip/fan/adjacency topologies (closeable: ~100-200 LoC in panfrost's `pan_nir_lower_xfb` or in panvk's IDVS handling)
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- Boundary-condition fatal-class bugs (closeable per-test)
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For OTHER Vulkan surface areas: not measured in iter15. The robustness2 / nullDescriptor (iter8) and Vulkan 1.1/1.2 surface (iter9) coverage is a parking-lot follow-up.
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## Reproducibility
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All artifacts in `/home/mfritsche/cts-results/` on ohm:
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- `cts_xfb.qpa.iter{1..7}` — per-iteration qpa logs
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- `xfb_fails.txt` — the 243 failing test names
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- `xfb_no_holes.txt` — the input caselist (133,596 tests)
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- `skipped_xfb.txt` — the 6 fatal tests
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- `cts_xfb.log` — wrapper log
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- `cts_run_resilient.sh` — the deqp-vk-resume-after-hang wrapper (durable in /home, survives ohm reboots)
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Re-running the same test against any future panvk-bifrost build:
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```
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/home/mfritsche/cts-results/cts_run_resilient.sh \
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/home/mfritsche/cts-results/xfb_no_holes.txt \
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/home/mfritsche/cts-results/cts_xfb_NEW.qpa \
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/home/mfritsche/cts-results/cts_xfb_NEW.log xfb
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```
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— claude-noether, 2026-05-21
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