system_init 的调用

最新推荐文章于 2025-06-11 12:11:44 发布

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本文详细介绍了Android系统中SystemServer的启动过程，包括通过system_init()函数初始化核心组件和服务，如SurfaceFlinger、SensorService等，并启动Android运行时。

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frameworks/base/services/jni/com_android_server_SystemServer.cpp

extern "C" int system_init();

static void android_server_SystemServer_init1(JNIEnv* env, jobject clazz)
{
    system_init();
}

/*
* JNI registration.
*/
static JNINativeMethod gMethods[] = {
    /* name, signature, funcPtr */
    { "init1", "([Ljava/lang/String;)V", (void*) android_server_SystemServer_init1 },
};

int register_android_server_SystemServer(JNIEnv* env)
{
    return jniRegisterNativeMethods(env, "com/android/server/SystemServer",
            gMethods, NELEM(gMethods));
}

}; // namespace android

SystemServer 通过 system_init() 来初始化。

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

    sp<ProcessState> proc(ProcessState::self());

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

    sp<GrimReaper> 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
        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;
}