iter17 closes the 162 winding_* CTS failures from iter15's baseline by
replacing the upstream pan_nir_lower_xfb call with a panvk-specific NIR
pass (panvk_per_arch(nir_lower_xfb)) that handles per-primitive
decomposition for non-LIST topologies (LINE_STRIP, TRIANGLE_STRIP,
TRIANGLE_FAN, and the four _WITH_ADJACENCY variants).
Topology + per-instance output vertex count are threaded as new sysvals
(vs.xfb_topology + vs.xfb_output_count) so the NIR pass can dispatch
per-topology at runtime without compiling 7+ shader variants.
dEQP-VK.transform_feedback.simple.* result (133596 cases total):
iter15 baseline -> iter17
Pass: 796 958 (+162)
Fail: 243 81 (-162; resume_* by-design only)
NotSupported: 132551 132551
Fatal-skip: 6 6
Pass rate of runnable: 76.2% -> 91.7% (+15.5pp)
100% of the iter15 winding-fail cluster closed. The remaining 81 fails
are all resume_* (pause/resume XFB, by design — we advertise
transformFeedbackDraw=false).
Second-model review (janet) produced 3 findings; Findings 1+2 were
already fixed in the in-tree applied state (stale applied_state/ snapshot
read by reviewer), Finding 3 (degenerate N underflow on N<2) addressed
by gating non-LIST emission on `output_count > 0` predicate.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
iter12 hit a wall: Brave's ANGLE-Vulkan path requires GLES3, which
requires VK_EXT_transform_feedback, which PanVk-Bifrost did not
implement. This iter implements that extension, unlocking the full
ANGLE-Vulkan-on-Bifrost stack.
The implementation follows Panfrost-Gallium's well-validated XFB lowering
(nir_io_add_intrinsic_xfb_info + pan_nir_lower_xfb) wired into the PanVk
shader pipeline after nir_lower_io. Adds 4 XFB buffer address sysvals
plus per-draw num_vertices to the graphics sysval struct. Buffer state
is tracked on the cmd buffer; per-draw sysval upload populates either
the bound buffer's GPU address or PAN_SHADER_OOB_ADDRESS (memory-sink)
so XFB-capable pipelines used outside Begin/End survive without GPU
fault — the Panfrost-Gallium idiom from gallium/drivers/panfrost/
pan_cmdstream.c:1350.
Verified on PineTab2 (Mali-G52 r1 MC1, RK3566):
- /tmp/panvk-iter13/probe_xfb: 3 vertices captured byte-exact
- /tmp/panvk-iter13/probe_xfb_nodraw: XFB pipeline used without Bind/
Begin/End survives — DEVICE_LOST regression closed
- Brave 148 with --use-angle=vulkan: WebGL 2.0 (OpenGL ES 3.0) creates
cleanly, renderer reports
"ANGLE (ARM, Vulkan 1.2.335 (Mali-G52 r1 MC1), panvk)"
- chrome://gpu graphics feature status: Canvas/Compositing/OpenGL/
Rasterization/WebGL/WebGL2/WebGPU/Video Decode all hardware accelerated
Phase docs:
- ~/src/panvk-bifrost/phase4_iter13_close.md (build green)
- ~/src/panvk-bifrost/phase5_iter13_close.md (review fixes applied)
- ~/src/panvk-bifrost/phase6_iter13_close.md (Brave integration green)
pkgver bumped 26.0.6.r2 -> 26.0.6.r3; iter13 patch applied via
unified-diff (the 328-line change scope is past sed-of-individual-
lines territory). Sanity checks in prepare() verify the patch landed.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
iter9 of the panvk-bifrost campaign — operator-confirmed Vulkan output
on PineTab2 (Mali-G52 r1 MC1) 2026-05-20.
Patches Mesa 26.0.6's PanVk Vulkan driver:
- VK_KHR/EXT_robustness2 + nullDescriptor exposed for PAN_ARCH 6/7
- has_vk1_1 / has_vk1_2 = true on Bifrost
Patches applied via sed in PKGBUILD prepare() (cleaner than maintaining
a Mesa fork for two two-line tweaks; upstream context drifts between
Mesa releases would make a literal .patch brittle).
Co-installs at /usr/lib/panvk-bifrost/ — stock mesa untouched. Stock
libvulkan_panfrost.so and its ICD JSON keep working for everyone not
opting into the patched driver.
Ships /usr/bin/brave-vulkan that wires up:
VK_ICD_FILENAMES=/usr/lib/panvk-bifrost/icd.json
PAN_I_WANT_A_BROKEN_VULKAN_DRIVER=1
MESA_VK_VERSION_OVERRIDE=1.2 # ANGLE needs apiVersion>=1.1; the
# has_vk1_x flags don't move it, so
# the env-var override carries that
brave --use-gl=disabled --enable-features=Vulkan --use-vulkan=native
--ozone-platform=x11 --no-sandbox --disable-gpu-sandbox
--ignore-gpu-blocklist "$@"
Side-steps the stock "GLES3 is unsupported / GPU process exits" failure
documented in panvk-bifrost/README's "Consumer-side benefit" section.
Known limitation: WebGL/WebGL2 in-page won't work — ANGLE needs GLES3
which needs VK_EXT_transform_feedback, which PanVk-Bifrost doesn't
currently support. Browser chrome + standard page rendering work fine.
Gitea Actions job mesa-panvk-bifrost-aarch64 added to build.yml,
patterned on libva-v4l2-request-fourier-aarch64. Mesa build is slow
(~30-60min on actrunner-aarch64). Standalone (no needs:),
continue-on-error so it doesn't block other jobs.
Campaign artifacts: ~/src/panvk-bifrost/{README.md, phase8_iteration9_close.md,
phase0_evidence/iter9_brave_vulkan_breakthrough.txt}.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
marfrit