/**
 * The main entry point from zygote.
 */
public static void main(String[] args) {
    new SystemServer().run();
}

private void run() {
    TimingsTraceAndSlog t = new TimingsTraceAndSlog();
    try {
        ... 代码省略

        // Create the system service manager.
        // 创建系统的服务管理者
        mSystemServiceManager = new SystemServiceManager(mSystemContext);
        
        ... 代码省略
    } finally {
        t.traceEnd();  // InitBeforeStartServices
    }

    ... 代码省略

    // Start services.
    try {
        // 启动引导服务
        startBootstrapServices(t);
        // 启动核心服务
        startCoreServices(t);
        // 启动其他服务
        startOtherServices(t);
    } catch (Throwable ex) {
        Slog.e("System", "******************************************");
        Slog.e("System", "************ Failure starting system services", ex);
        throw ex;
    } finally {
        t.traceEnd(); // StartServices
    }

    ... 代码省略

    // Loop forever.
    Looper.loop();
    throw new RuntimeException("Main thread loop unexpectedly exited");
}

// We now tell the activity manager it is okay to run third party
// code.  It will call back into us once it has gotten to the state
// where third party code can really run (but before it has actually
// started launching the initial applications), for us to complete our
// initialization.
mActivityManagerService.systemReady(() -> {
    ... 代码省略
}