Graphics Streaming Kit (formerly: Vulkan Cereal)

Graphics Streaming Kit is a code generator that makes it easier to serialize and forward graphics API calls from one place to another:

• From a virtual machine guest to host for virtualized graphics
• From one process to another for IPC graphics
• From one computer to another via network sockets

Build: Linux

The latest directions for the standalone Linux build are provided here.

Build: Windows

Make sure the latest CMake is installed. Make sure Visual Studio 2019 is installed on your system along with all the Clang C++ toolchain components. Then:

mkdir build
cd build
cmake . ../ -A x64 -T ClangCL

A solution file should be generated. Then open the solution file in Visual studio and build the gfxstream_backend target.

Build: Android for host

Be in the Android build system. Then:

m libgfxstream_backend

It then ends up in out/host

This also builds for Android on-device.

Output artifacts

libgfxstream_backend.(dll|so|dylib)

Regenerating Vulkan code

To re-generate both guest and Vulkan code, please run:

scripts/generate-gfxstream-vulkan.sh

Regenerating GLES/RenderControl code

First, build build/gfxstream-generic-apigen. Then run:

scripts/generate-apigen-source.sh

Tests

Windows Tests

There are a bunch of test executables generated. They require libEGL.dll and libGLESv2.dll and vulkan-1.dll to be available, possibly from your GPU vendor or ANGLE, in the %PATH%.

Android Host Tests

There are Android mock testa available, runnable on Linux. To build these tests, run:

m GfxstreamEnd2EndTests

Structure

• CMakeLists.txt: specifies all host-side build targets. This includes all backends along with client/server setups that live only on the host. Some
  • Backend implementations
  • Implementations of the host side of various transports
  • Frontends used for host-side testing with a mock implementation of guest graphics stack (mainly Android)
  • Frontends that result in actual Linux/macOS/Windows gles/vk libraries (isolation / fault tolerance use case)
• Android.bp: specifies all guest-side build targets for Android:
  • Implementations of the guest side of various transports (above the kernel)
  • Frontends
• BUILD.gn: specifies all guest-side build targets for Fuchsia
  • Implementations of the guest side of various transports (above the kernel)
  • Frontends
• base/: common libraries that are built for both the guest and host. Contains utility code related to synchronization, threading, and suballocation.
• protocols/: implementations of protocols for various graphics APIs. May contain code generators to make it easy to regen the protocol based on certain things.
• host-common/: implementations of host-side support code that makes it easier to run the server in a variety of virtual device environments. Contains concrete implementations of auxiliary virtual devices such as Address Space Device and Goldfish Pipe.
• stream-servers/: implementations of various backends for various graphics APIs that consume protocol. gfxstream-virtio-gpu-renderer.cpp contains a virtio-gpu backend implementation.

Guest Vulkan design

gfxstream vulkan is the most actively developed component. Some key commponents of the current design include:

• 1:1 threading model - each guest Vulkan encoder thread gets host side decoding thread
• Support for both virtio-gpu, goldish and testing transports.
• Support for Android, Fuchsia, and Linux guests.
• Ring Buffer to stream commands, in the style of io_uring.
• Mesa embedded to provide dispatch and objects.
• Currently, there are a set of Mesa objects and gfxstream objects. For example, struct gfxstream_vk_device and the gfxstream object goldfish_device both are internal representations of Vulkan opaque handle VkDevice. The Mesa object is used first, since Mesa provides dispatch. The Mesa object contains a key to the hash table to get a gfxstream internal object (for example, gfxstream_vk_device::internal_object). Eventually, gfxstream objects will be phased out and Mesa objects used exclusively.