marfrit
e323aa2316
Adds 0008-panvk-bifrost-bump-max-image-dim-3d-for-dawn.patch. Two-hunk patch:
Hunk 1: Bumps maxImageDimension3D from 512 to 2048 on Bifrost (PAN_ARCH 7..10).
Surfaced by panvk-bifrost-perf-measurement iter1 spike: Brave's WebGPU/Dawn
detects panvk-bifrost as a Vulkan adapter on Mali-G52 r1 MC1 but rejects it
because the advertised limit is below WebGPU's 2048 minimum (per
third_party/dawn/src/dawn/native/vulkan/PhysicalDeviceVk.cpp:746). This is
the actual unblock for the campaign's stated motivator — Chromium GPU
process Vulkan boot on PineTab2 / Bifrost SBCs.
Per Vulkan 1.3 spec §43.1, maxImageDimensionXD is the upper bound on any
creatable image; per-format limits MAY be smaller. On PAN_ARCH<=10 the
per-format limit caps at ~1023 per axis for RGBA8 within the 4 GB
max_img_size_B address constraint. Apps trying 2048^3 with thick formats
hit the per-format limit at image-create — per-spec behavior.
Hunk 2: Removes three asserts in get_max_3d_image_size() that encoded the
wrong invariant (per-format >= basic), opposite of what the Vulkan spec
mandates. The asserts were release-mode-masked via NDEBUG, but debug
builds would abort the first time Dawn (or any client) called
vkGetPhysicalDeviceImageFormatProperties on a 3D image format. Surfaced
by Phase 5 2nd-model review.
Verified on PineTab2 (Mali-G52 r1 MC1, PAN_ARCH 7):
- vulkaninfo: maxImageDimension3D = 2048
- Brave/Dawn: "Insufficient Vulkan limits" warning eliminated; adapter
accepted for WebGPU.
- CTS regression: dEQP-VK.api.copy_and_blit.core.image_to_image.3d_images.*
6/6 Pass (unchanged from r7 baseline).
Phase 5 (2nd-model) review: APPROVE WITH CHANGES — both changes applied
(release-mode + debug-mode assert exposure addressed by removing the
wrong-invariant asserts).
Note on numbering: r8 was attempted (KHR_depth_clamp_zero_one trim) but
abandoned mid-Phase-3 when it surfaced that 5 more post-1.3.10 KHR
extensions are advertised — surgically false-gating all of them would
risk undoing r1's KHR_robustness2 work for Chromium Dawn. Documented at
~/src/panvk-bifrost/iter21/phase0to3_close_no_ship.md.
Cross-refs:
- ~/src/panvk-bifrost/iter22/phase0to2_max3d_close.md (Phase 0-2 close)
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
mesa-panvk-bifrost
Patched Mesa libvulkan_panfrost.so exposing Bifrost-gen Mali GPUs
(Mali-G31/G52/G72/G76, PAN_ARCH 6/7) to Chromium-family browsers'
Vulkan compositor.
Result of the panvk-bifrost campaign (~/src/panvk-bifrost/),
iter9 close 2026-05-20 (technical milestone — operator-confirmed Brave
window) followed by this package as the actual delivery.
What it solves
Stock Chromium / Brave on Bifrost SBCs (PineTab2, etc.) currently dies at GL bindings init:
ERROR: ui/gl/gl_context_egl.cc:120 GLES3 is unsupported and ES version fallback is disabled
ERROR: ui/gl/init/gl_factory.cc:111 Requested GL implementation not found
ERROR: components/viz/service/main/viz_main_impl.cc:189 Exiting GPU process due to errors during initialization
This package makes Brave's Vulkan compositor path work on Bifrost, side-stepping the failing GL stack. Browser chrome and standard page rendering work.
Known limitations (not addressed)
- WebGL / WebGL2 in-page: blocked. ANGLE needs
VK_EXT_transform_feedbackto expose GLES3 contexts; PanVk-Bifrost doesn't currently support that. Sites using WebGL will degrade or refuse. - VAAPI hardware video decode: unrelated to this package — see the
libva-v4l2-request-fourierpackage for that path.
Install
# Ensure [marfrit] is in /etc/pacman.conf, then:
sudo pacman -Sy mesa-panvk-bifrost
Use
brave-vulkan # launches Brave with Vulkan
brave-vulkan https://www.example.com
brave-vulkan --your-flags-here # extra args passed through
The launcher sets:
VK_ICD_FILENAMES=/usr/lib/panvk-bifrost/icd.json(the patched driver)PAN_I_WANT_A_BROKEN_VULKAN_DRIVER=1(Mesa upstream gate)MESA_VK_VERSION_OVERRIDE=1.2(apiVersion bump for ANGLE)- Brave flags:
--use-gl=disabled --enable-features=Vulkan --use-vulkan=native --ozone-platform=x11 --no-sandbox --disable-gpu-sandbox --ignore-gpu-blocklist
What's in the package
/usr/lib/panvk-bifrost/libvulkan_panfrost.so— patched Mesa Vulkan driver (Mesa 26.0.6 + 2 sed-applied patches)/usr/lib/panvk-bifrost/icd.json— Vulkan ICD JSON pointing at the patched .so (NOT auto-loaded; only viaVK_ICD_FILENAMES)/usr/bin/brave-vulkan— launcher script
System Mesa is untouched. The stock /usr/lib/libvulkan_panfrost.so and
/usr/share/vulkan/icd.d/panfrost_icd.json continue to work for any
other Vulkan app.
Co-existence
Both stock Mesa and this package can be installed. Stock Vulkan apps
(vulkaninfo, vkcube, etc.) use the stock driver by default. Only
apps started via brave-vulkan (or with VK_ICD_FILENAMES manually
set to our path) use the patched driver.
Campaign close criterion
Per feedback_package_done_means_installable
three-point check:
- PR merged to
marfrit-packages - CI green AND
packages.reauktion.de/arch/aarch64/mesa-panvk-bifrost-*.pkg.tar.zstexists pacman -Ss mesa-panvk-bifroston a fresh consumer host (e.g. ohm afterpacman -Syufrom clean state) returns the package + brave-vulkan launches
When all three pass, panvk-bifrost iter9 closes.