mesa-panvk-bifrost: new package — Vulkan-compositor Brave for Bifrost SBCs

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>

arch/mesa-panvk-bifrost/brave-vulkan

@@ -0,0 +1,61 @@
+#!/bin/bash
+# brave-vulkan — launch Brave with the PanVk-Bifrost Vulkan compositor on
+# Bifrost SBCs (PineTab2 / Mali-G52 r1 MC1 and similar).
+#
+# Side-steps the GL stack failures stock Brave hits on Bifrost
+# (the README "Consumer-side benefit" path of the panvk-bifrost campaign).
+#
+# Provided by the mesa-panvk-bifrost package. See:
+#   /usr/share/doc/mesa-panvk-bifrost/README
+#   ~/src/panvk-bifrost/phase8_iteration9_close.md (campaign close)
+#
+# Usage: brave-vulkan [brave args...]
+# Equivalent to: brave [VULKAN_FLAGS] [your args]
+
+set -e
+
+# Patched Vulkan driver (from this package) — must point at the custom path
+# so we don't clash with the stock /usr/share/vulkan/icd.d/panfrost_icd.json
+export VK_ICD_FILENAMES=/usr/lib/panvk-bifrost/icd.json
+
+# PanVk's "I know it's not conformant" gate — the patched driver still
+# refuses to enumerate Bifrost without this env var (Mesa upstream choice,
+# kept for compatibility).
+export PAN_I_WANT_A_BROKEN_VULKAN_DRIVER=1
+
+# Override apiVersion to 1.2 — ANGLE (Chromium's GL stack) requires
+# device.apiVersion >= 1.1. The patched libvulkan_panfrost.so still has
+# a PAN_ARCH>=10 gate inside get_api_version(); easier to override at
+# runtime via this Mesa env var than to add a third patch.
+export MESA_VK_VERSION_OVERRIDE=1.2
+
+# Find the live Plasma session's Xauthority. On a fresh boot the suffix
+# is randomized; pgrep the Xwayland args to find the current one.
+if [ -z "${XAUTHORITY:-}" ]; then
+    XAUTHF=$(pgrep -fa Xwayland 2>/dev/null | grep -oE "/run/user/$(id -u)/xauth_[A-Za-z0-9]+" | head -1)
+    if [ -n "$XAUTHF" ]; then
+        export XAUTHORITY="$XAUTHF"
+    fi
+fi
+
+# Standard session env if not already set
+: "${XDG_RUNTIME_DIR:=/run/user/$(id -u)}"
+export XDG_RUNTIME_DIR
+
+# Default to the active Plasma Wayland session if WAYLAND_DISPLAY unset
+: "${WAYLAND_DISPLAY:=wayland-0}"
+export WAYLAND_DISPLAY
+
+# Default to the XWayland :1 unless DISPLAY is set
+: "${DISPLAY:=:1}"
+export DISPLAY
+
+exec brave \
+    --use-gl=disabled \
+    --enable-features=Vulkan \
+    --use-vulkan=native \
+    --ozone-platform=x11 \
+    --no-sandbox \
+    --disable-gpu-sandbox \
+    --ignore-gpu-blocklist \
+    "$@"