piglit on Android against MobileGL

Run piglit desktop-GL tests on a connected Android device with MobileGL as the OpenGL implementation, for both backends:

DirectGLES — MobileGL over the system GLES driver (or ANGLE with --use-angle)
DirectVulkan — MobileGL over the system Vulkan driver

No APK and no on-device python: piglit test binaries run as the adb shell user from /data/local/tmp, create contexts through waffle's surfaceless_egl platform, and waffle is pointed at libMobileGL.so (which exports the full egl*/gl* API under real names).

How it fits together

piglit test binary (aarch64, bionic)
  └─ waffle surfaceless_egl (patched)
       ├─ WAFFLE_EGL_LIBRARY=libMobileGL.so   → dlopen MobileGL as the EGL impl
       ├─ WAFFLE_GL_LIBRARY=libMobileGL.so    → waffle_dl_sym resolves gl* here
       ├─ WAFFLE_FORCE_GL_CONTEXT_VERSION=33core
       │    upgrades low compat context requests to GL 3.3 core (never
       │    downgrades) so piglit's supports_gl_compat_version=10 tests run
       └─ WAFFLE_ANDROID_WINDOW=imagereader   (DirectVulkan only)
            windows are AImageReader ANativeWindows instead of EGL pbuffers,
            because Android ICDs lack VK_EXT_headless_surface which the
            MobileGL pbuffer path needs
  └─ libMobileGL.so
       ├─ DirectGLES: dlopens the real system libEGL.so internally
       └─ DirectVulkan: links libvulkan.so

Key rule: never name MobileGL libEGL.so anywhere on LD_LIBRARY_PATH — the DirectGLES backend loads the system driver with a bare-soname dlopen("libEGL.so") and would recursively pick itself up.

One-time setup (host: macOS/Linux with the Android NDK)

WORK=path/to/workdir && cd $WORK
git clone --depth 1 https://gitlab.freedesktop.org/mesa/piglit.git
git clone --depth 1 https://gitlab.freedesktop.org/mesa/waffle.git
git -C waffle apply $MOBILEGL/tools/piglit-android/patches/waffle-mobilegl-android.patch
git -C piglit apply $MOBILEGL/tools/piglit-android/patches/piglit-mobilegl-android.patch
python3 -m venv venv && ./venv/bin/pip install mako numpy packaging

The piglit patch matters beyond build fixes: upstream's piglit_dispatch_default_init runs while the waffle framework is still being constructed (gl_fw is NULL), so the waffle resolvers were never installed and GL functions bound through the system libEGL's eglGetProcAddress — every test silently ran on the raw GLES driver instead of MobileGL.

Build MobileGL for Android:

cmake -S $MOBILEGL -B $MOBILEGL/build-android-arm64 -G Ninja \
  -DCMAKE_TOOLCHAIN_FILE=$NDK/build/cmake/android.toolchain.cmake \
  -DANDROID_ABI=arm64-v8a -DANDROID_PLATFORM=android-26 \
  -DCMAKE_BUILD_TYPE=RelWithDebInfo
cmake --build $MOBILEGL/build-android-arm64 --target MobileGL -j
$NDK/toolchains/llvm/prebuilt/*/bin/llvm-strip --strip-unneeded \
  -o $WORK/libMobileGL-stripped.so $MOBILEGL/build-android-arm64/libMobileGL.so

Cross-build waffle (meson; a cross file and a stub egl.pc pointing at MobileGL's bundled EGL 1.5 headers are needed — see cross-example/):

cd $WORK/waffle
meson setup build-android --cross-file $WORK/cross/android-arm64.ini \
  -Dbuildtype=release -Dsurfaceless_egl=enabled \
  -Dglx=disabled -Dx11_egl=disabled -Dgbm=disabled -Dwayland=disabled \
  -Dbuild-tests=false -Dbuild-examples=false -Dprefix=$WORK/prefix
ninja -C build-android && meson install -C build-android

Cross-build piglit (needs PKG_CONFIG_LIBDIR with the installed waffle-1.pc plus the stub egl.pc):

cd $WORK/piglit && export PKG_CONFIG_LIBDIR=$WORK/prefix/lib/pkgconfig:$WORK/cross/pkgconfig
cmake -S . -B build-android -G Ninja \
  -DCMAKE_TOOLCHAIN_FILE=$NDK/build/cmake/android.toolchain.cmake \
  -DANDROID_ABI=arm64-v8a -DANDROID_PLATFORM=android-26 \
  -DCMAKE_BUILD_TYPE=Release \
  -DPIGLIT_USE_WAFFLE=ON -DPIGLIT_BUILD_GL_TESTS=ON \
  -DPIGLIT_BUILD_GLES1_TESTS=OFF -DPIGLIT_BUILD_GLES2_TESTS=OFF \
  -DPIGLIT_BUILD_GLES3_TESTS=OFF -DPIGLIT_BUILD_EGL_TESTS=OFF \
  -DPIGLIT_BUILD_GLX_TESTS=OFF -DPIGLIT_BUILD_WGL_TESTS=OFF \
  -DPIGLIT_BUILD_CL_TESTS=OFF -DPIGLIT_BUILD_VK_TESTS=OFF \
  -DPIGLIT_BUILD_DMA_BUF_TESTS=OFF -DPIGLIT_USE_GBM=OFF \
  -DPIGLIT_USE_WAYLAND=OFF -DPIGLIT_USE_X11=OFF \
  -DPYTHON_EXECUTABLE=$WORK/venv/bin/python \
  -DOPENGL_INCLUDE_DIR=$MOBILEGL/include \
  -DOPENGL_gl_LIBRARY=$SYSROOT/usr/lib/aarch64-linux-android/26/libEGL.so \
  -DGLEXT_INCLUDE_DIR=$MOBILEGL/include
ninja -C build-android

Selecting tests

Enumerate on the host with piglit's own profiles (no device needed):

cd $WORK/piglit
for prof in opengl shader glslparser; do
  PIGLIT_BUILD_DIR=$PWD/build-android ./venv/bin/python ./piglit print-cmd \
    -t "spec@!opengl 3[.]" -t "spec@glsl-3[.]30" $prof
done > /tmp/gl33.list

Group names use @ separators (spec@!opengl 3.3@minmax). The version groups (spec@!opengl 1.x…3.3), GLSL groups (spec@glsl-1.10…3.30) plus the ARB extension groups folded into GL 3.1–3.3 core give a comprehensive "GL 3.3 core" suite (~15k tests).

Running

python3 $MOBILEGL/tools/piglit-android/run_piglit_android.py \
  --piglit-root $WORK/piglit --list /tmp/gl33.list \
  --backend DirectGLES \
  --mobilegl-lib $WORK/libMobileGL-stripped.so \
  --waffle-lib $WORK/waffle/build-android/src/waffle/libwaffle-1.so \
  --out results-gles
# then the same with --backend DirectVulkan --out results-vk

The runner pushes binaries/libs/data (incremental; --repush forces), executes tests serially in chunked on-device shell scripts under timeout, parses the PIGLIT: {...} result lines, and writes results.json + summary.txt + raw.log. Exit-code semantics: parsed result wins; nonzero exit without a result line = crash; toybox timeout exits = timeout.

Quick sanity check for the whole stack (waffle build also produces wflinfo):

adb shell 'cd /data/local/tmp/piglit-mgl && env LD_LIBRARY_PATH=$PWD/lib \
  WAFFLE_EGL_LIBRARY=libMobileGL.so WAFFLE_GL_LIBRARY=libMobileGL.so \
  MOBILEGL_BACKEND_TYPE=DirectVulkan WAFFLE_ANDROID_WINDOW=imagereader \
  ./wflinfo --platform surfaceless_egl --api gl --version 3.3 --profile core'

Expect OpenGL version string: 3.3.0 MobileGL …, Direct (Vulkan) Backend.

Known caveats

MSAA winsys configs never match (MobileGL exposes two RGBA8888 configs, samples=0); MSAA FBO tests are unaffected.
Tests that genuinely require compatibility-profile features will fail on the forced 3.3 core context; that is honest for a core-only implementation.
eglTerminate at test exit now tears MobileGL down deterministically (see the EGL-lifecycle refactor); a device-side mobilegl.log is written per run directory for debugging.

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