android system server 启动流程

 start app_process from init

init.rc

service zygote /system/bin/app_process -Xzygote /system/bin --zygote --start-system-server

   

    socket zygote stream 666

    onrestart write /sys/android_power/request_state wake

    onrestart write /sys/power/state on

    onrestart restart media

    onrestart restart netd

frameworks/base/cmds/app_process/app_main.cpp::main

        if (0 == strcmp("--zygote", arg)) {

            bool startSystemServer = (i < argc) ?

                    strcmp(argv[i], "--start-system-server") == 0 : false;

            setArgv0(argv0, "zygote");

            set_process_name("zygote");

            runtime.start("com.android.internal.os.ZygoteInit",

                startSystemServer);

        } else {

frameworks/base/core/jni/AndroidRuntime.cpp::start

void AndroidRuntime::start(const char* className, const bool startSystemServer)

{

    LOGD("\n>>>>>> AndroidRuntime START %s <<<<<<\n",

            className != NULL ? className : "(unknown)");

    ..

    JNIでcallStatic

    com.android.internal.os.ZygoteInit#main

frameworks/base/core/java/com/android/internal/os/ZygoteInit.java#main

            if (argv[1].equals("true")) {

                startSystemServer();

            } else if (!argv[1].equals("false")) {

                throw new RuntimeException(argv[0] + USAGE_STRING);

            }

frameworks/base/core/java/com/android/internal/os/ZygoteInit.java#startSystemServer

        String args[] = {

            "--setuid=1000",

            "--setgid=1000",

            "--setgroups=1001,1002,1003,1004,1005,1006,1007,1008,1009,1010,3001,3002,3003",

            "--capabilities=130104352,130104352",

            "--runtime-init",

            "--nice-name=system_server",

            "com.android.server.SystemServer",

        };

        ...

        try {

            parsedArgs = new ZygoteConnection.Arguments(args);

            ...

            /* Request to fork the system server process */

            pid = Zygote.forkSystemServer(

                    parsedArgs.uid, parsedArgs.gid,

                    parsedArgs.gids, debugFlags, null,

                    parsedArgs.permittedCapabilities,

                    parsedArgs.effectiveCapabilities);

framesorks/base/services/java/com/android/server/SystemServer.java

SystemServer#main

    public static void main(String[] args) {

        ...       

        System.loadLibrary("android_servers");

        init1(args);  // <-- native method

    }

frameworks/base/services/jni/com_android_server_SystemServer.cpp

static void android_server_SystemServer_init1(JNIEnv* env, jobject clazz)

{

    system_init();

}

frameworks/base/cmds/system_server/library/system_init.cpp

system_init

Start services written in C++

- SurfaceFlinger

- SensorService

- AudioFlinger

- MediaPlayerService

- CameraService

- AudioPolicyService

callStatic by JNI com/android/server/SystemServer#init2

framesorks/base/services/java/com/android/server/SystemServer.java

    public static final void init2() {

        Slog.i(TAG, "Entered the Android system server!");

        Thread thr = new ServerThread();

        thr.setName("android.server.ServerThread");

        thr.start();

    }

ServerThread#run

Start services written in Java

- Entropy Service

- Power Manager

- Activity Manager

- Telephony Registry

- Package Manager

- Account Manager

- Content Manger

- System Content Providers

- Battery Service

- Lights Service

- Vibrator Service

- Alarm Manager

- Init Watchdog

- Window Manager

- Bluetooth Service

- Device Policy

- Status Bar

- Clipboard Service

- Input Method Service

- NetStat Service

- NetworkMnagement Service

- Connectivity Service

- Throttle Service

- Accessibility Manager

- Mount Service

- Notification Manager

- Device Storage Monitor

- Location Manager

- Search Service

- DropBox Service

- Wallpaper Service

- Audio Service

- Headset Observer

- Dock Observer

- USB Observer

- UI Mode Manager Service

- Backup Service

- AppWidget Service

- Recognition Service

- DiskStats Service

These services create threads as needs. All those threads are running in the System Server process.

In the normal Linux system, these services are independent process.