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- plan-B §8.3 asks which tier `AcquirePersistentMap` lands in, but the probe only
asked Vulkan. DirectGLES ("Espryt") reaches a persistent map through
`glBufferStorageEXT` + `glMapBufferRange(PERSISTENT|COHERENT)`, not a
`VkDeviceMemory` map, so a Vulkan-only answer decides nothing for that backend.
Add a GLES leg to T1: the exported fd imported with `glCreateMemoryObjectsEXT`
+ `glImportMemoryFdEXT` + `glBufferStorageMemEXT`, then mapped
PERSISTENT|COHERENT -- in-process first (isolates "GL can import this fd" from
"the fd survives a process boundary"), then cross-process (new `t1gl` child).
Drivers disagree about how the import must be phrased, so each attempt walks a
ladder over {dedicated flag} x {import size = memory requirement or the fd's
own size} x {buffer size} and reports the rung the driver accepted plus every
rejected rung with its GL error -- a driver *preference* must never be reported
as a missing capability. A driver that backs the storage but refuses
PERSISTENT|COHERENT is reported separately from one that refuses the storage:
that distinction is exactly T1 vs T2 for DirectGLES. The T0 GLES leg
(`EGL_ANDROID_get_native_client_buffer` + `glBufferStorageExternalEXT` +
persistent map, verified by `AHardwareBuffer_lock` on the client side) now
reports every step's GL enum and requires the persistent flags for OK.
- the verdict was unfalsifiable: T1 reported PARTIAL when neither leg had moved a
byte. Replace it with an explicit decisive-leg model -- OK only when every
decisive leg round-tripped in both directions, PARTIAL when at least one did,
FAIL otherwise with the failing step and its driver error named in `why:`.
Every row now opens with a per-leg trace (`vkimport[D]=rt gpu[D]=rt`). The raw
`mmap` leg is informational for opaque-fd (Vulkan forbids interpreting that
payload outside the driver, so a refusal is conformant) and decisive for
dma-buf, where a CPU mapping is the point of the handle type.
- T3 never ran the direction that would make it a tier: both ends were the
importing process. Add `T3-client-memfd-server-import` (new `t3c` child) -- the
client creates and writes the memfd, the server mmaps the received fd, imports
the client's host pointer into a `VkDeviceMemory`, reads what the client wrote,
writes back, and takes a GPU access on the client's memory, which the client
then verifies through its own mapping.
- no route touched the GPU, so an OK proved only that a map call returned a
pointer. Every tier row now takes a real GPU access before it can be OK:
`vkCmdCopyBuffer` out of the shared allocation into private staging (mismatch =
the GPU could not read what the peer wrote) plus `vkCmdFillBuffer` into it,
queue-idle and an explicit host-read barrier, with the peer checking the filled
region through its own mapping. VkCtx grows a queue and command pool for it.
- the device run executes in the `shell` SELinux domain, not the `untrusted_app`
domain MobileGL runs in, and the two do not share dmabuf/gralloc rules. Print
uid/pid/`/proc/self/attr/current` in a run-context header, repeat the caveat in
the summary, and document in README.md how to answer it for the real domain
later (exec the same binary from the trace app's spike hook, spike-A package)
without implementing that here.
- `vkStr()` returned a pointer into one static buffer while several results
routinely appear in one format call, so all of them showed the last one; it
returns std::string now, `memFlagStr` likewise, and `fmt`/`pr` carry
`format(printf)` so a missed `.c_str()` is a compile error rather than UB.
- `advertisedExportable` decided the status at the allocate site but not at the
`vkGetMemoryFdKHR` site. One rule at every export failure now
(`exportFailStatus`): advertised EXPORTABLE and then declining is FAIL, never
advertised is UNSUPPORTED. Export + map + fd is factored into `exportHostVisible`.
- `T0-ahb-blob-transfer` was recorded OK on the socket handoff alone. The handoff
keeps its own informational row; the tier row is now composed at the end from
the full import+map+compare+writeback chain over the Vulkan, GL and GPU legs.
- `mmapErrno` kept the first attempt's errno after the second-chance mmap
succeeded, so a working mapping carried a failure code; it is cleared on
success and the first errno moves into the note.
- a failed `glImportMemoryFdEXT` no longer closes the fd: EXT_memory_object_fd
does not say whether ownership still transfers on failure and Mesa closes it
either way, so closing risks a double close landing on the socket. Leaking a
handful of dups in a short-lived probe is the safe side of that trade.
- validated end to end on the host harness (lavapipe + llvmpipe,
`VK_DRIVER_FILES=lvp_icd.json EGL_PLATFORM=surfaceless`): T1-opaque-fd OK,
T3-external-memory-host OK, T3-memfd-cross-process OK,
T3-client-memfd-server-import OK, T1-dma-buf UNSUPPORTED (not advertised
exportable). The two T1-gles rows FAIL there with GL_OUT_OF_MEMORY on every
ladder rung although GL_DEVICE_UUID_EXT matches the Vulkan deviceUUID --
llvmpipe's GL does not implement importing a lavapipe opaque-fd allocation,
a Mesa interop gap recorded in README.md so a device FAIL stays attributable.
Rebuilt for arm64-v8a with NDK r27d (PIE, android-30); the device run is
pending, both device locks are held by another campaign.
MobileGL
A desktop OpenGL implementation
MobileGL is a free and open-source project that implements a desktop OpenGL API. The goal is to provide a complete desktop OpenGL implementation with a state management layer and multi-backend support.
Note
Status: In development. Parts of the codebase are incomplete. Current short-term target: OpenGL 4.2 (Core Profile).
Project positioning
MobileGL is an implementation of a desktop OpenGL library. It aims to provide:
- Full OpenGL state management.
- A front-end that exposes OpenGL functions.
- Multiple independent backend implementations, where each backend targets a specific graphics API and remains fully isolated from others.
This project is intended as an implementation/translation layer.
Key components
The repository is organized into following top-level modules:
- MG_State — state tracking and management logic for Graphics APIs.
- MG_Impl — front-end implementations of Graphics APIs that interact with
MG_StateandMG_Backend. - MG_Backend — per-backend translation layer that maps front-end Graphics APIs' semantics and state into concrete backend API calls (e.g. OpenGL ES, Vulkan).
- MG_Util and other utility modules.
Third-party components
MobileGL reuses several open-source projects:
- SPIRV-Cross by KhronosGroup - Apache License 2.0: github
- glslang by KhronosGroup - Various Licenses: github
- DiligentCore by Diligent Graphics - Apache License 2.0: github
- flat_hash_map by Malte Skarupke - Boost Software License 1.0: github
Refer to each component's repository for exact license texts. Any bundled third-party code in this repository is included under the upstream project's license.
Compatibility & target
- Short-term target:
OpenGL 4.2 (Core Profile). - Current development focus:
- Performance improvement
MG_StateandMG_ImplforOpenGL 4.2 (Core Profile)Direct (Vulkan)backendDirect (OpenGL ES)backend
Build Instructions
We currently provide no releases and no precompiled binaries.
If you want to try the project right now, you’ll need to build it yourself:
-
Clone the repository:
git clone https://github.com/MobileGL-Dev/MobileGL.git -
Initialize and update all submodules recursively:
git submodule update --init --recursive -
Follow glslang’s own documentation for its required initiation.
-
Configure and build the project with CMake:
cmake -B build cmake --build buildor do it in a modern way:
cmake -S . -B build -G Ninja -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ cmake --build buildAlternatively, you can use platform-specific build commands as needed.
Build For macOS
On macOS, MobileGL can be built as a dylib that exposes the normal OpenGL/CGL/NSOpenGL entry points and routes them to the DirectVulkan backend. This is useful for running applications such as Minecraft through their stock GLFW/LWJGL OpenGL path while MobileGL is injected before context creation.
Prerequisites:
- macOS with Clang and Ninja.
- Vulkan loader and MoltenVK installed. With Homebrew, the MoltenVK ICD is commonly located at
/opt/homebrew/etc/vulkan/icd.d/MoltenVK_icd.json.
Configure and build:
cmake -S . -B build-macos-magma \
-G Ninja \
-DCMAKE_BUILD_TYPE=Release \
-DMOBILEGL_BACKEND_TYPE=DirectVulkan \
-DMOBILEGL_BUILD_TEST=OFF \
-DMOBILEGL_BUILD_BENCHMARK=OFF
cmake --build build-macos-magma --target MobileGL -j8
The dylib will be generated at:
build-macos-magma/libMobileGL.dylib
To run Minecraft by MobileGL from a launcher like PrismLauncher, keep the stock LWJGL/GLFW natives and add a wrapper command to the instance settings:
env DYLD_INSERT_LIBRARIES=/absolute/path/to/MobileGL/build-macos-magma/libMobileGL.dylib MOBILEGL_BACKEND_TYPE=DirectVulkan VK_ICD_FILENAMES=/opt/homebrew/etc/vulkan/icd.d/MoltenVK_icd.json
Also make sure the JVM arguments include:
-XstartOnFirstThread
DYLD_INSERT_LIBRARIES must be active before GLFW creates its OpenGL context. After startup, the Minecraft F3 screen should report MobileGL and the Direct (Vulkan) backend if the injection worked.
Build Options
| Option | Description | Default |
|---|---|---|
MOBILEGL_BUILD_TEST |
Build MobileGL tests (requires Clang) | ON |
MOBILEGL_BUILD_BENCHMARK |
Build MobileGL benchmarks (requires Clang) | ON |
MOBILEGL_FORCE_RELEASE_OPT |
Enable O3 and LTO in Debug build | ON |
MOBILEGL_ENABLE_TRACY |
Enable Tracy profiler for performance analysis | OFF |
Notes:
- The project requires C++23.
MG_TestandMG_Benchmarkcan only be built with Clang, not GCC. To enforce Clang, add-DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++to your command.- On Android, tests and benchmarks are always disabled.
Environment Variables
MobileGL supports runtime configuration via environment variables.
Supported Keys
| Variable | Description | Allowed Values | Default |
|---|---|---|---|
MOBILEGL_BACKEND_TYPE |
Select active backend implementation at startup. | DirectGLES, DirectVulkan |
DirectGLES |
MOBILEGL_DISABLE_TIMERQUERY |
Disable GPU timer-query exposure and use. | 0, 1 |
0 |
MOBILEGL_ESPRYT_USE_ANGLE |
Load ANGLE EGL/GLES libraries. | 0, 1 |
0 |
MOBILEGL_MAGMA_DISABLE_SUBGROUP |
Disable Vulkan shader subgroup support. | 0, 1 |
0 |
MOBILEGL_ADVERTISE_FP64 |
Advertise GL_ARB_gpu_shader_fp64. GLSL double/dvec/dmat compile and run either way - they are narrowed to 32 bits - so this only changes whether an application is told it has 64-bit precision, which it does not. |
0, 1 |
0 |
MOBILEGL_MAGMA_R11G11B10F_FALLBACK |
Use Magma's R11G11B10F format fallback. | 0, 1 |
0 |
MOBILEGL_MAGMA_FRAMESINFLIGHT |
Set Magma frames in flight. | Integer 1–64 |
3 |
MOBILEGL_ESPRYT_AVOID_SAMPLER_MIPMAP_MIN_FILTER |
Avoid sampler mipmap minification filters. | 0, 1 |
0 |
MOBILEGL_COHERENT_AS_FLUSH |
Treat persistent GL_MAP_FLUSH_EXPLICIT_BIT maps as coherent (app-compat for engines like Flywheel that never flush them). |
0, 1 |
0 |
MOBILEGL_ESPRYT_FORCE_DS_READBACK_EMULATION |
Always emulate depth/stencil glReadPixels/glGetTexImage by shader sampling on Espryt, instead of using the driver's own depth/stencil readback where it has one. |
0, 1 |
0 |
VK_ICD_FILENAMES |
Select the Vulkan ICD used by the Vulkan loader. | Path to an ICD JSON file | Loader default |
License
This project is distributed under GNU LGPL v3.0. See the LICENSE file in the repository for detailed information.