iter19 close + r5 full sweep scoreboard
Adds iter19 campaign-close doc (mesa-panvk-bifrost r7 ship, XFB packed-varying channel-extract fix). Also lands the r5 full dEQP-VK sweep scoreboard (2.26M tests, 97.65% runnable pass rate) that surfaced the holes_vert crash in the first place. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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# iter19 — XFB store channel-extract fix for packed varyings (campaign close)
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Shipped: 2026-05-25
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PR: https://git.reauktion.de/marfrit/marfrit-packages/pulls/96
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Merge commit: 902de73a02d9
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Package: `mesa-panvk-bifrost-26.0.6.r7-1-aarch64`
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## What shipped
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Single 21+/3- line patch to `src/panfrost/vulkan/panvk_vX_xfb_lower.c`
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(`0007-panvk-bifrost-xfb-component-base-fix.patch`). Eliminates a
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reproducible SIGSEGV in `vkCreateGraphicsPipeline` for any shader with
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XFB-bound varyings declared at non-zero `layout (component=N)`.
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## How surfaced
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The r5 full dEQP-VK sweep (2,258,378 tests, 97.65% runnable pass rate)
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on 2026-05-24/25 included 27 fails in `transform_feedback` plus a
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SIGKILL on the chunk when `transform_feedback.simple.holes_vert` hit
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`FATAL ERROR: Test program crashed`. Isolated repro produced a userspace
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SIGSEGV with no kernel GPU fault (dmesg clean), pointing at a pure
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libvulkan_panfrost bug.
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## Root cause
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`lower_xfb_output_iter17` (and identically upstream
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`pan_nir_lower_xfb.c::lower_xfb_output`, which carries a `// TODO`)
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computed the source-channel mask as `mask << channel_idx`. `channel_idx`
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is the varying-location component (0..3) but `src` only contains
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channels starting at `nir_intrinsic_component(intr)`. For a scalar
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declared `layout (component=2) flat out float vegeta`, NIR emits
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`store_output src=<vec1>, component=2`, and the lowering computed
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`mask << 2` against a 1-component src — out-of-range; the malformed
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nir_def then segfaulted during downstream NIR constant-folding in
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`nir_constant_expressions.c::evaluate_*`.
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The `assert(nir_intrinsic_component(intr) == 0)` precondition was
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inherited from upstream Mesa as a documented `// TODO`; release builds
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(`-DNDEBUG`) elided it, turning the precondition violation directly
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into a SIGSEGV.
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## Fix
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1. Compute `src_channel = channel_idx - nir_intrinsic_component(intr)`
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and use `mask << src_channel` instead.
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2. Convert both elided asserts to explicit release-mode early-return
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guards (closes the same elision class as the original bug).
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3. Add a dispatcher-side comment explaining why `i*2+j` is the
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varying-location component index.
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## Verification
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| Family | Result |
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|----------------------------------------------|-------------------|
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| `transform_feedback.simple.holes_vert` | Crash → Fail (color) |
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| `transform_feedback.simple.holes_extra_draw_vert` | Crash → Fail (color) |
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| `transform_feedback.simple.basic_*` | 36/36 Pass |
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| `transform_feedback.simple.depth_clip_*` | 1 Pass + 4 NotSupp |
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| `transform_feedback.simple.lines_or_triangles*` | 16 NotSupp |
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| `transform_feedback.simple.holes_geom*` | NotSupp (no GS on G52) |
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Zero new regressions on previously passing tests.
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## Process
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Full 8-step bugfix process followed:
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- Phase 0 — characterize: `iter19/phase0_holes_vert_close.md`
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- Phase 1 — source map: `iter19/phase1_holes_vert_situation.md`
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- Phase 2 — root-cause + ranked options: `iter19/phase2_holes_vert_situation.md`
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- Phase 3 — implement + inner-test: `iter19/phase3_holes_vert_close.md`
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- Phase 4 — wider verify (focused subset)
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- Phase 5 — 2nd-model review: **APPROVE WITH CHANGES (non-blocking)** → defensive-guards added
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- Phase 7 — final retest: clean
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- Phase 8 — ship: r7 PR → CI green → marfrit repo published → ohm `pacman -S` upgraded → smoke test confirms Crash→Fail
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## Three-point ship-check verdict
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1. ✓ PR #96 merged at `902de73a02d9`
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2. ✓ CI runs #1380 (`mesa-panvk-bifrost-aarch64`) and #1381 (`mesa-panvk-bifrost-video-aarch64`) both `success`
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3. ✓ `pacman -Q mesa-panvk-bifrost` on ohm reports `26.0.6.r7-1`; installed lib BuildID `9f8dacfc...`; holes_vert no longer SIGSEGVs
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## Open follow-ups (not blocking r7 ship)
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- **iter20: holes_vert color-check residual** — when `panvk_per_arch(nir_lower_xfb)` removes the original store_output post-XFB-lowering, varyings that are *both* XFB-bound *and* read by the fragment shader lose their rasterizer-side path. holes_vert's fragment shader sees `goku`/`vegeta` as undef → outputs black instead of expected blue. Naive "keep store_output" probe fixed color but blew up compile-time on `max_output_components_128` — needs a more nuanced fix.
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- **iter20+: pre-existing latent crashes** unmasked by r7 — `dEQP-VK.transform_feedback.simple.max_output_components_{64,128,256}` coredump on shipped r6 baseline too (confirmed independently); they were never reached during the r5 sweep because the watchdog killed transform_feedback after holes_vert.
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## Lineage
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| rev | What | Date |
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|-----|-----------------------------------------------|------------|
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| r1 | KHR_robustness2 + nullDescriptor + nullDescriptor on Bifrost | iter8 |
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| r2 | has_vk1_1/has_vk1_2 = true on Bifrost | iter9 |
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| r3 | VK_EXT_transform_feedback (iter13) | iter13 |
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| r4 | XFB primitive decomposition (iter17) | iter17 |
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| r5 | fragmentStoresAndAtomics = true | 2026-05-23 |
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| r6 | VK_EXT_legacy_dithering | 2026-05-25 |
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| **r7** | **XFB packed-varying channel-extract fix** | **2026-05-25** |
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