android从init到开机动画启动关闭流程一简易图(surfaceflinger启动的位置)

init主进程启动，解析init.rc后依次exec fork启动相关的进程，其中以class main和core为首的service将会率先启动，这里SF将会触发init启动一个bootanimation进程，其会开始启动动画显示，后台其他服务进程完成初始化，待Systemserver的其他核心service启动后，ActivityManagerService将会初始化完成并启动第一个lunch activity即桌面程序，在渲染图像前，需要让SF停止动画的显示，故由AMS通知SF停止显示，以方便Lunch最终display到UI上。这段显示的时间，基本就是后台服务的初始化运行，其中以SystemServer的耗时较长，导致开机动画一直循环显示。

通过 property_get("system_init.startsurfaceflinger", propBuf, "1");

在init.rc来决定启动的sufaceflinger在systemsever还是直接由init的main启动。

extern "C" status_t system_init()
{
ALOGI("Entered system_init()");

sp proc(ProcessState::self());

sp sm = defaultServiceManager();
ALOGI("ServiceManager: %p\n", sm.get());

sp grim = new GrimReaper();
sm->asBinder()->linkToDeath(grim, grim.get(), 0);

char propBuf[PROPERTY_VALUE_MAX];
property_get("system_init.startsurfaceflinger", propBuf, "1");
if (strcmp(propBuf, "1") == 0) {
// Start the SurfaceFlinger   //在 init.rc中通过setprop system_init.startsurfaceflinger 0或者1，属性值为如果是1则在Systemserver中直接启动，否则以一个单独的main进程启动                                                                                                 SurfaceFlinger::instantiate();    }

property_get("system_init.startsensorservice", propBuf, "1");
if (strcmp(propBuf, "1") == 0) {
// Start the sensor service
SensorService::instantiate();
}

// And now start the Android runtime.  We have to do this bit
// of nastiness because the Android runtime initialization requires
// some of the core system services to already be started.
// All other servers should just start the Android runtime at
// the beginning of their processes's main(), before calling
// the init function.
ALOGI("System server: starting Android runtime.\n");
AndroidRuntime* runtime = AndroidRuntime::getRuntime();

ALOGI("System server: starting Android services.\n");
JNIEnv* env = runtime->getJNIEnv();
if (env == NULL) {
return UNKNOWN_ERROR;
}
jclass clazz = env->FindClass("com/android/server/SystemServer");
if (clazz == NULL) {
return UNKNOWN_ERROR;
}
jmethodID methodId = env->GetStaticMethodID(clazz, "init2", "()V");
if (methodId == NULL) {
return UNKNOWN_ERROR;
}
env->CallStaticVoidMethod(clazz, methodId);

ALOGI("System server: entering thread pool.\n");
ProcessState::self()->startThreadPool();
IPCThreadState::self()->joinThreadPool();
ALOGI("System server: exiting thread pool.\n");

return NO_ERROR;

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