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Before this, CONTRACT-P6 5.3's own sentence held: "a dead server leaves the
client silently DECLINE-ing every verb forever with glGetError clean".
FatalCode::DeviceLost had zero producers and zero consumers and
glGetGraphicsResetStatus returned GL_NO_ERROR unconditionally, so an
application had no way to learn that the process holding its GPU objects was
gone. Measured cost of that: a server killed on its first Clear left the
client waiting out the full 120 s barrier and reporting Fatal{BarrierTimeout}
- the wrong diagnosis, two minutes late. It now notices in 0.01 s.
THE MACHINERY WAS ALREADY THERE. Doorbell::Wait breaks out on Dead(),
SessionProducer::Park turns that into SessionWait::ShutDown, and ClientSession
already had the named DECLINED path. What did not exist was the death FACT:
D5c's finding is that the client parks on clientBell[0] and rings ITSELF
through clientBell[1], holding both ends, so EOF can never arrive on the one
descriptor it watches. A bell that can wake itself cannot hear a death.
SetDeathWitness(fd) fixes that with no new descriptor: the control socket's
far end is held only by the server. The subtlety is that the bell must watch a
socket it must NEVER read - the transport's reassembler owns those bytes and a
control reply is not a death. So the witness enters the poll set with
`events = POLLRDHUP` and nothing else: POLLHUP/POLLERR/POLLNVAL arrive in
revents unrequested, so the hangup is seen while POLLIN never is. Nothing is
recv'd from it and its ownership stays with SocketTransport.
Dead() AND PeerHungUp() ARE TWO FACTS. Park sets m_dead for POLLERR, POLLNVAL
and unrecognised revents too - each a fault in THIS process's descriptor - and
CondVarDoorbell::Kill() sets it on every orderly Stop(). A latch taken from
Dead() would report a lost GPU for a local fd bug and a context reset for
every clean exit, so only PeerHungUp() arms it.
GL_UNKNOWN_CONTEXT_RESET, not GUILTY or INNOCENT: those assign blame, and the
server died for a reason that never crossed the wire.
D5b, in the control-reply wait, which had the right comment and no code: EOF
on the control stream is device loss; a TIMEOUT with the socket still open is
"ALIVE BUT SILENT" and says so by name. 5.4 forbids calling a frozen or merely
slow peer dead, and under P5e run-ahead a server one frame behind is the
INTENDED steady state - a latch armed by a deadline would fire on a healthy
session under load.
MOBILEGL_IPC_RESPAWN is now a NAMED REFUSAL rather than a variable nothing
reads. The latch is one-way on purpose: every handle this client minted names
an object inside the server process, so recovery means re-pushing the world.
THREE TEST NAMES ADDED, none renamed (G14), and R-16 run both ways:
* remove the witness -> AKilledServerLatchesDeviceLostFromTheHangupAndNot-
ADeadline goes red, takes 2 s instead of 0.01 s, and names D5c.
* collapse PeerHungUp() into Dead() -> ADeadBellIsNotAlwaysAHungUpPeer goes
red naming the local-fd-bug consequence.
* AnOrderlyStopIsNotADeviceLoss stays GREEN under that collapse, and its
comment now says so. The first draft claimed it was the control for it;
running the falsification proved otherwise - under spawn the self bell is a
SocketDoorbell and Stop() never kills one. The comment was corrected rather
than the claim quietly kept.
G1 RE-MEASURED, NOT ASSUMED: 0 symbol diff against the c6 baseline and .text
unchanged at 0xa52203. That measurement earned its keep - it caught a 16-byte
drift that had nothing to do with dl: P6's O_APPEND log-sink fix was compiling
into the PULL build, where a second process can never exist. Now guarded, and
.text is back to the baseline exactly.
Full unit suite: 2350 tests, the same two pre-existing environmental failures
and no others. All six OpenRA arms (2 backends x monolith/inproc/spawn) green.
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.