failed to create debugfs directory
最编程
2024-08-13 20:30:13
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「failed to create debugfs directory」这个错误消息通常表示内核在创建debugfs文件系统时出现了问题。debugfs是一种特殊的文件系统，用于存储调试信息。
如果你在使用Linux内核时遇到了这个错误，通常可以通过以下步骤解决：
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确定你的内核版本是否支持debugfs。
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在内核配置中启用debugfs支持，并重新编译内核。
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使用命令「mount -t debugfs none /sys/kernel/debug」将debugfs挂载到/sys/kernel/debug目录。
如果以上步骤都不能解决问题，可以考虑寻求技术支持或者在社区中寻找帮助。
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UserActionEvent.EVENT_TOGGLE_WIFI_ON : UserActionEvent.EVENT_TOGGLE_WIFI_OFF); } if (!mIsControllerStarted) { Log.e(TAG,"WifiController is not yet started, abort setWifiEnabled"); return false; } mWifiMetrics.incrementNumWifiToggles(isPrivileged, enable); if(staId == STA_PRIMARY) mActiveModeWarden.wifiToggled; else if(staId == STA_SECONDARY && (getNumConcurrentStaSupported > 1) && (getWifiEnabledState == WifiManager.WIFI_STATE_ENABLED)) mActiveModeWarden.qtiWifiToggled(staId, enable); else Log.e(TAG,"setWifiEnabled not allowed for Id: " + staId); return true; } 四、可以看到wifiservice调用了ActiveModeWarden的wifiToggled，发送了CMD_WIFI_TOGGLED的消息，通知WiFi切换了。 frameworks/opt/net/wifi/service/java/com/android/server/wifi/ActiveModeWarden.java public void wifiToggled { mWifiController.sendMessage(WifiController.CMD_WIFI_TOGGLED); } 五、我们看WifiController是怎么处理这个消息的。WifiController是ActiveModeWarden中的一个状态机，用来管理WiFi的操作，包括热点啊飞行模式什么的。 打开WiFi之前，状态机应该是在Disabled状态，我们看Disable状态里的处理。 class DisabledState extends BaseState { public boolean processMessageFiltered(Message msg) { switch (msg.what) { case CMD_WIFI_TOGGLED: case CMD_SCAN_ALWAYS_MODE_CHANGED: if (shouldEnableSta) { startClientModeManager; transitionTo(mEnabledState); } break; 启动一个新的客户端管理。 private boolean startClientModeManager { Log.d(TAG, "Starting ClientModeManager"); ClientListener listener = new ClientListener; ClientModeManager manager = mWifiInjector.makeClientModeManager(listener); listener.setActiveModeManager(manager); manager.start; if (!switchClientModeManagerRole(manager)) { return false; } mActiveModeManagers.add(manager); return true; } 六、start了ClientModeManager frameworks/opt/net/wifi/service/java/com/android/server/wifi/ClientModeManager.java public void start { Log.d(TAG, "Starting with role ROLE_CLIENT_SCAN_ONLY"); mRole = ROLE_CLIENT_SCAN_ONLY; mTargetRole = ROLE_CLIENT_SCAN_ONLY; mStateMachine.sendMessage(ClientModeStateMachine.CMD_START); } 看一下是谁处理了这个START消息呢 private class IdleState extends State { @Override public boolean processMessage(Message message) { switch (message.what) { case CMD_START: // Always start in scan mode first. mClientInterfaceName = mWifiNative.setupInterfaceForClientInScanMode( mWifiNativeInterfaceCallback); if (TextUtils.isEmpty(mClientInterfaceName)) { Log.e(TAG, "Failed to create ClientInterface. Sit in Idle"); mModeListener.onStartFailure; break; } transitionTo(mScanOnlyModeState); break; } } 七、这里可以看出，WifiNative先去启动HAL frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiNative.java public String setupInterfaceForClientInScanMode( @NonNull InterfaceCallback interfaceCallback) { synchronized (mLock) { if (!startHal) { mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToHal; return null; } Iface iface = mIfaceMgr.allocateIface(Iface.IFACE_TYPE_STA_FOR_SCAN); iface.externalListener = interfaceCallback; iface.name = createStaIface(iface); if (!mWifiCondManager.setupInterfaceForClientMode(iface.name, Runnable::run, new NormalScanEventCallback(iface.name), new PnoScanEventCallback(iface.name))) { Log.e(TAG, "Failed to setup iface in wificond=" + iface.name); teardownInterface(iface.name); mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToWificond; return null; } iface.networkObserver = new NetworkObserverInternal(iface.id); if (!registerNetworkObserver(iface.networkObserver)) { teardownInterface(iface.name); return null; } mWifiMonitor.startMonitoring(iface.name); onInterfaceStateChanged(iface, isInterfaceUp(iface.name)); iface.featureSet = getSupportedFeatureSetInternal(iface.name); return iface.name; } } 八、启动HAL WifiVendorHal.java-->startVendorHal --> HalDeviceManager.java --> startWifi --> IWifi.start mWifi.start方法是启动实际加载WiFi动作的调用，这里涉及HIDL机制调用。通过获取IWifi接口对象，调用其方法。这里IWifi接口对象是IWifi.hal文件中实现。 android/hardware/interfaces/wifi/1.0/IWifi.hal 在编译时，编译器会将IWifi.hal解析为IWifi.java文件,直接看该文件中的start方法实现即可。 android/out/soong//.intermediates/hardware/interfaces/wifi/1.0/android.hardware.wifi-V1.0-java_gen_java/gen/srcs/android/hardware/wifi/V1_0/IWifi.java public android.hardware.wifi.V1_0.WifiStatus start throws android.os.RemoteException { try { ... ... ... ... mRemote.transact(3 /* start */, _hidl_request, _hidl_reply, 0 /* flags */); _hidl_reply.verifySuccess; _hidl_request.releaseTemporaryStorage; return _hidl_out_status; } finally { _hidl_reply.release; } } 通过binder调用，将调用到wifi.cpp中的start方法. android/hardware/interfaces/wifi/1.4/default/wifi.cpp Return<void> Wifi::start(start_cb hidl_status_cb) { return validateAndCall(this, WifiStatusCode::ERROR_UNKNOWN, &Wifi::startInternal, hidl_status_cb); } wifi.cpp->start ==> wifi.cpp->startInternal ==> wifi.cpp->initializeModeControllerAndLegacyHal ==> WifiModeController->initialize ==> DriverTool->LoadDriver 通过调用DriverTool->LoadDriver将返回到Android framework中。下面是LoadDriver的实现。 android/frameworks/opt/net/wifi/libwifi_hal/include/wifi_hal/driver_tool.cpp bool DriverTool::LoadDriver { return ::wifi_load_driver == 0; } 在wifi_load_driver方法中，将调用系统接口加载WiFi驱动ko。关于系统insmod接口的调用，本文不做分析。到这里，已梳理完在WifiNative类中调用的startHal方法。 android/frameworks/opt/net/wifi/libwifi_hal/wifi_hal_common.cpp int wifi_load_driver { ... ... ... ... insmod(file,args); ... ... ... ... } 调用WifiNl80211Manager类的setupInterfaceForClientMode方法。 该类的主要对WiFi 80211nl管理接口的封装，接口在WiFicond守护进程中呈现给WiFi框架。该类提供的接口仅使用与WiFi框架，访问权限受selinux权限保护。 setupInterfaceForClientMode方法主要为Station模式设置接口。 android/frameworks/base/wifi/java/android/net/wifi/nl80211/WifiNl80211Manager.java public boolean setupInterfaceForClientMode(@NonNull String ifaceName, @NonNull @CallbackExecutor Executor executor, @NonNull ScanEventCallback scanCallback, @NonNull ScanEventCallback pnoScanCallback) { ... ... ... ... // Refresh Handlers mClientInterfaces.put(ifaceName, clientInterface); try { IWifiScannerImpl wificondScanner = clientInterface.getWifiScannerImpl; mWificondScanners.put(ifaceName, wificondScanner); Binder.allowBlocking(wificondScanner.asBinder); ScanEventHandler scanEventHandler = new ScanEventHandler(executor, scanCallback); mScanEventHandlers.put(ifaceName, scanEventHandler); wificondScanner.subscribeScanEvents(scanEventHandler); PnoScanEventHandler pnoScanEventHandler = new PnoScanEventHandler(executor, pnoScanCallback); mPnoScanEventHandlers.put(ifaceName, pnoScanEventHandler); wificondScanner.subscribePnoScanEvents(pnoScanEventHandler); ... ... ... ... } 到这里，ClientModeStateMachine状态机在IdleState状态成功处理完了CMD_START消息。状态机将转到“mScanOnlyModeState”状态，将会执行以下调用流程(具体原因可查看状态机机制)。 IdleState.exit->StartedState.enter->StartedState.exit->ScanOnlyModeState.enter。 九、启动HAL以后，就要启动supplicant了。 在第五步的时候我们调用了ActiveModeWarden.java的startClientModeManagerh函数。start以后会执行switchClientModeManagerRole
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