android surfaceflinger boot

 Surface Flinger boot flow in Android system

• a executable surfaceflinger in framework/base/cmds/surfaceflinger

                      main() –>
                      SurfaceFlinger::instantiate(); –>
                      defaultServiceManager()→addService(String16(「SurfaceFlinger」), new SurfaceFlinger());

• a executable system_server framework/base/cmds/system_server

                       start system_server when system boot in init.rc
                       main() –> system_init(); –>
                       SurfaceFlinger::instantiate();

• surface flinger flow:

                       surface flinger extend a threads (framework/base/libs/utils/threads.cpp ) –SurfaceFlinger.cpp
                       start SurfaceFlinger::readyToRun in Thread::_threadLoop(); –SurfaceFlinger.cpp
                       DisplayHardware* const hw = new DisplayHardware(this, dpy); –SurfaceFlinger.cpp
                       DisplayHardware::init() –DisplayHardware.cpp
                       EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY) (implement in ligagl.so or libhgl.so)
                       mDisplaySurface = new EGLDisplaySurface();
                       surface = eglCreateWindowSurface(display, config, mDisplaySurface.get(), NULL);
                      context = eglCreateContext(display, config, NULL, NULL); ( Create our OpenGL ES context in libagl.so or libhgl.so)
                      open copybit & overlay modules:

                      mBlitEngine = NULL;     
                      if (hw_get_module(COPYBIT_HARDWARE_MODULE_ID, &module) == 0)
                      {           copybit_open(module, &mBlitEngine);        }      
                      mOverlayEngine = NULL;     
                       if (hw_get_module(OVERLAY_HARDWARE_MODULE_ID, &module) == 0)
                       {           overlay_control_open(module, &mOverlayEngine);        }

• agl / hgl exchange：

                     framework/base/opengl/libs/egl.cpp (libGLESv1_CM.so)
                     eglGetDisplay() in egl.cpp, dynamically load all our EGL implementations( agl/hgl ) for that display and call into the real eglGetGisplay()
                      provide base egl APIs wappers in egl.cpp and implementaton in libagl.so or libhgl.so

• Surface Flinger SystemSurface flinger provides system-wide surface 「composer」, handling all surface rendering to frame. buffer device

                       Can combine 2D and 3D surfaces and surfaces from multiple applications
                       Surfaces passed as buffers via Binder IPC calls
                       Can use OpenGL ES and 2D hardware accelerator for its compositions
                       Double-buffering using page-flip

• Surface Flinger flowIn Android, every window gets implemented with an underlying Surface object, an object that gets placed on the framebuffer by SurfaceFlinger, the system-wide screen composer. Each Surface is double-buffered using page-flips. The back buffer is where drawing takes place and the front buffer is used for composition.

• Surface flinger handling all surface rendering to frame. buffer device. It can combine 2d and 3d surfaces and surfaces from multiple applications. Surfaces are passed as buffers via binder interprocess (IPC) calls. It can use OpenGL ES and 2d hardware acceleration for its compositions. System integrators can plug in hardware acceleration using a plug-in standard from Khronos.