Bootstrap服务

startBootstrapServices() 不是按类名排列的服务清单，而是一组相互纠缠的最小依赖图。Android 17 的源码把 ART module manager、Watchdog、Installer、ActivityManager/ActivityTaskManager、PowerManager、DisplayManager、PackageManager 和 SensorService 放在一条有明确前置条件的顺序上。

本文只追踪 Bootstrap 组的调用方、状态变化、生效时机和失败传播；Core、Other、Apex 服务留给后续文章。

1. 组入口与trace

源码文件：frameworks/base/services/java/com/android/server/SystemServer.java

private void startBootstrapServices(@NonNull TimingsTraceAndSlog t) {
    t.traceBegin("startBootstrapServices");
    // 依赖纠缠的基础服务按源码顺序启动。
    ...
    t.traceEnd();
}

SystemServer.run() 只调用一次该方法；每个内部 traceBegin/traceEnd 是启动耗时和失败定位的阶段边界。任一服务抛异常都会被 run() 的 StartServices catch 记录并重新抛出，Core/Other/Apex 不再执行。

2. ART与Watchdog

t.traceBegin("ArtModuleServiceInitializer");
ArtModuleServiceInitializer.setArtModuleServiceManager(
        new ArtModuleServiceManager());
t.traceEnd();

t.traceBegin("StartWatchdog");
final Watchdog watchdog = Watchdog.getInstance();
watchdog.start();
mDumper.addDumpable(watchdog);
t.traceEnd();

ART module manager 来自独立 service-art.jar。源码注释要求它早于 DexUseManagerLocal 和 PackageManagerService：class linker 与 GC 互斥，而 PMS 会大量分配对象，过晚加载可能持续等待 GC。Watchdog 紧接着启动，目的是从早期启动阶段就能检测主线程或关键 handler 的死锁。

3. 日志与兼容

ServiceManager.addService(
        Context.PROTOLOG_CONFIGURATION_SERVICE,
        new ProtoLogConfigurationServiceImpl());
ProtoLog.init(WmProtoLogGroups.values());

PlatformCompat platformCompat =
        new PlatformCompat(mSystemContext);
ServiceManager.addService(
        Context.PLATFORM_COMPAT_SERVICE, platformCompat);
ServiceManager.addService(
        Context.PLATFORM_COMPAT_NATIVE_SERVICE,
        new PlatformCompatNative(platformCompat));
AppCompatCallbacks.install(
        new long[0], new long[0], false);

ProtoLog 与 PlatformCompat 通过 ServiceManager 进入跨进程名称表；AppCompatCallbacks 写入当前 runtime 的兼容性状态。AMS、PMS 等后续消费者依赖 PlatformCompat，所以它必须在这些服务前发布。

4. Installer前置

mSystemServiceManager.startService(FileIntegrityService.class);
Installer installer = mSystemServiceManager.startService(
        Installer.class);
mSystemServiceManager.startService(
        DeviceIdentifiersPolicyService.class);

FileIntegrityService 要在应用成为第一个消费者前启动；Installer 通过 installd 准备 /data/user 等关键目录和权限。installer 实例随后传给 PackageManagerService.main()，因此这里建立的是后续调用方会消费的对象状态。

5. 策略迁移

源码文件：frameworks/base/services/java/com/android/server/SystemServer.java

mSystemServiceManager.startService(FeatureFlagsService.class);
mSystemServiceManager.startService(
        UriGrantsManagerService.Lifecycle.class);
mSystemServiceManager.startService(PowerStatsService.class);
startIStatsService();
startMemtrackProxyService();

LocalServices.addService(PermissionMigrationHelper.class,
        new PermissionMigrationHelperImpl());
LocalServices.addService(AppOpMigrationHelper.class,
        new AppOpMigrationHelperImpl());
mSystemServiceManager.startService(AccessCheckingService.class);

两个 migration helper 用 LocalServices 供同一 SystemServer 进程消费，不会生成 ServiceManager handle；AccessCheckingService 再通过 SystemService 生命周期接入。

6. ATM与AMS顺序

ActivityTaskManagerService atm =
        mSystemServiceManager.startService(
                ActivityTaskManagerService.Lifecycle.class)
                .getService();
mActivityManagerService =
        ActivityManagerService.Lifecycle.startService(
                mSystemServiceManager, atm);
mActivityManagerService.setSystemServiceManager(
        mSystemServiceManager);
mActivityManagerService.setInstaller(installer);
mWindowManagerGlobalLock = atm.getGlobalLock();

ATM 先创建，再把实例交给 AMS 生命周期启动；AMS 保存 SystemServiceManager/Installer，并暴露后续系统进程状态。mWindowManagerGlobalLock 从 ATM 取出，成为 Activity/Window 协调的锁 owner。

7. Power与数据加载

源码文件：frameworks/base/services/java/com/android/server/SystemServer.java

mDataLoaderManagerService =
        mSystemServiceManager.startService(
                DataLoaderManagerService.class);
mIncrementalServiceHandle = startIncrementalService();

mPowerManagerService = mSystemServiceManager.startService(
        PowerManagerService.class);
mSystemServiceManager.startService(ThermalManagerService.class);
mActivityManagerService.initPowerManagement();

DataLoader/Incremental 必须早于 PMS；PowerManager 要尽早处理 native daemon 的 Binder 请求，并在 AMS 初始化 power management 前可用。

8. Display与PMS

mSystemServiceManager.startService(
        RecoverySystemService.Lifecycle.class);
mSystemServiceManager.startService(LightsService.class);
mDisplayManagerService = mSystemServiceManager.startService(
        DisplayManagerService.class);
mSystemServiceManager.startBootPhase(
        t, SystemService.PHASE_WAIT_FOR_DEFAULT_DISPLAY);

DomainVerificationService domainVerificationService =
        new DomainVerificationService(
                mSystemContext, SystemConfig.getInstance(),
                platformCompat);
mSystemServiceManager.startService(domainVerificationService);

Watchdog.getInstance().pauseWatchingCurrentThread(
        "packagemanagermain");
try {
    mPackageManagerService = PackageManagerService.main(
            mSystemContext, installer,
            domainVerificationService,
            mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF);
} finally {
    Watchdog.getInstance().resumeWatchingCurrentThread(
            "packagemanagermain");
}

DisplayManager 先提供 display metrics，再通过 PHASE_WAIT_FOR_DEFAULT_DISPLAY 建立默认 display，PMS 才继续初始化。PMS 主初始化可能很慢，源码只暂停当前线程的 Watchdog 监控并在 finally 恢复，不是关闭 Watchdog。

9. Bootstrap收束

源码文件：frameworks/base/services/java/com/android/server/SystemServer.java

mUserManagerService = mSystemServiceManager
        .startService(UserManagerService.LifeCycle.class)
        .getService();
AttributeCache.init(mSystemContext);
mActivityManagerService.setSystemProcess();
platformCompat.registerPackageReceiver(mSystemContext);
watchdog.init(mSystemContext, mActivityManagerService);
mDisplayManagerService.setupSchedulerPolicies();
mSystemServiceManager.startService(
        new OverlayManagerService(mSystemContext));
mSystemServiceManager.startService(
        new ResourcesManagerService(mSystemContext));
mSystemServiceManager.startService(
        new SensorPrivacyService(mSystemContext));
mSystemServiceManager.startService(SensorService.class);

PMS 成功后，Bootstrap 才能建立 UserManager、AttributeCache、system process、Watchdog 的 AMS 绑定、Display scheduler、Overlay、Resources、SensorPrivacy 和 Sensor。SensorService 放在最后，因为源码明确要求它依赖 PackageManager、AppOps 和权限服务。

10. 失败定位与导航

• ART/class linker：检查 ArtModuleServiceInitializer 是否早于 PMS；
• 目录/权限：检查 Installer、installd 和 PMS 入参；
• ATM/AMS：检查 lifecycle 启动与 global lock；
• Display：检查 DisplayManager 和 PHASE_WAIT_FOR_DEFAULT_DISPLAY；
• PMS：区分 Watchdog 暂停期间的合法长任务与真实异常；
• Sensor：确认 PackageManager、AppOps 和权限服务已经完成。

# 输入 Bootstrap 方法，输出服务调用顺序和 trace 标签。
rg -n "startBootstrapServices|ArtModuleServiceInitializer|StartWatchdog|StartInstaller|StartActivityManager|StartPowerManager|StartDisplayManager|StartPackageManagerService|StartSensorService" \
  frameworks/base/services/java/com/android/server/SystemServer.java

# 输入生命周期管理器，输出 startService/startBootPhase 的实例化和回调。
rg -n "startService\\(|startBootPhase\\(|mServices|onStart" \
  frameworks/base/services/core/java/com/android/server/SystemServiceManager.java

下一篇将展开 startCoreServices()，不会重复本文的 Bootstrap 依赖和 PackageManager 前置条件。