下面的函数主要初始化PnP发现的设备，并为它安装服务，代码如下：

#001 NTSTATUS

#002 IopInitializePnpServices(IN PDEVICE_NODE DeviceNode)

#003 {

#004 DEVICETREE_TRAVERSE_CONTEXT Context;

#005

#006 DPRINT("IopInitializePnpServices(%p)/n",DeviceNode);

#007

构造一个响应子服务发现的操作。

#008 IopInitDeviceTreeTraverseContext(

#009 &Context,

#010 DeviceNode,

#011 IopActionInitChildServices,

#012 DeviceNode);

#013

开始遍历整个设备树。

#014 return IopTraverseDeviceTree(&Context);

#015 }

#016

初始化每个设备节点，如下：

#001 NTSTATUS

#002 IopActionInitChildServices(PDEVICE_NODE DeviceNode,

#003 PVOID Context)

#004 {

#005 PDEVICE_NODE ParentDeviceNode;

#006 NTSTATUS Status;

#007 BOOLEAN BootDrivers = !PnpSystemInit;

#008

#009 DPRINT("IopActionInitChildServices(%p,%p)/n",DeviceNode,Context);

#010

取父节点设备。

#011 ParentDeviceNode = (PDEVICE_NODE)Context;

#012

#013 /*

#014 * We are called for the parent too,but we don't need to do special

#015 * handling for this node

#016 */

如果下一个节点等于父节点，没有子节点，就直接返回。

#017 if (DeviceNode == ParentDeviceNode)

#018 {

#019 DPRINT("Success/n");

#020 return STATUS_SUCCESS;

#021 }

#022

#023 /*

#024 * Make sure this device node is a direct child of the parent device node

#025 * that is given as an argument

#026 */

#027 #if 0

#028 if (DeviceNode->Parent != ParentDeviceNode)

#029 {

#030 /*

#031 * Stop the traversal immediately and indicate unsuccessful operation

#032 */

#033 DPRINT("Stop/n");

#034 return STATUS_UNSUCCESSFUL;

#035 }

#036 #endif

#037

判断这个节点是否可以安装服务。

#038 if (!IopDeviceNodeHasFlag(DeviceNode,DNF_DISABLED) &&

#039 !IopDeviceNodeHasFlag(DeviceNode,DNF_ADDED) &&

#040 !IopDeviceNodeHasFlag(DeviceNode,DNF_STARTED))

#041 {

#042 PLDR_DATA_TABLE_ENTRY ModuleObject;

#043 PDRIVER_OBJECT DriverObject;

#044

获取已经存在驱动程序指针。

#045 /* Get existing DriverObject pointer (in case the driver has

#046 already been loaded and initialized) */

#047 Status = IopGetDriverObject(

#048 &DriverObject,

#049 &DeviceNode->ServiceName,

#050 FALSE);

#051

#052 if (!NT_SUCCESS(Status))

#053 {

#054 /* Driver is not initialized,try to load it */

#055 Status = IopLoadServiceModule(&DeviceNode->ServiceName,&ModuleObject);

#056

#057 if (NT_SUCCESS(Status) || Status == STATUS_IMAGE_ALREADY_LOADED)

#058 {

#059 /* STATUS_IMAGE_ALREADY_LOADED means this driver

#060 was loaded by the bootloader */

#061 if ((Status != STATUS_IMAGE_ALREADY_LOADED) ||

#062 (Status == STATUS_IMAGE_ALREADY_LOADED && !DriverObject))

#063 {

初始化这个设备的驱动程序。

#064 /* Initialize the driver */

#065 Status = IopInitializeDriverModule(DeviceNode,ModuleObject,

#066 &DeviceNode->ServiceName,FALSE,&DriverObject);

#067 }

#068 else

#069 {

#070 Status = STATUS_SUCCESS;

#071 }

#072 }

#073 else

#074 {

#075 DPRINT1("IopLoadServiceModule(%wZ) Failed with status 0x%08x/n",

#076 &DeviceNode->ServiceName,Status);

#077 }

#078 }

#079

设备驱动程序已经加载，开始初始化入口点。

#080 /* Driver is loaded and initialized at this point */

#081 if (NT_SUCCESS(Status))

#082 {

添加低层次的过滤驱动程序。

#083 /* Attach lower level filter drivers. */

#084 IopAttachFilterDrivers(DeviceNode,TRUE);

初始化设备。

#085 /* Initialize the function driver for the device node */

#086 Status = IopInitializeDevice(DeviceNode,DriverObject);

#087

#088 if (NT_SUCCESS(Status))

#089 {

#090 /* Attach upper level filter drivers. */

#091 IopAttachFilterDrivers(DeviceNode,FALSE);

#092 IopDeviceNodeSetFlag(DeviceNode,DNF_STARTED);

#093

启动这个设备。

#094 Status = IopStartDevice(DeviceNode);

#095 }

#096 else

#097 {

#098 DPRINT1("IopInitializeDevice(%wZ) Failed with status 0x%08x/n",

#099 &DeviceNode->InstancePath,Status);

#100 }

#101 }

#102 else

#103 {

设置引导驱动程序不可以再加载。

#104 /*

#105 * Don't disable when trying to load only boot drivers

#106 */

#107 if (!BootDrivers)

#108 {

#109 IopDeviceNodeSetFlag(DeviceNode,DNF_DISABLED);

#110 IopDeviceNodeSetFlag(DeviceNode,DNF_START_Failed);

#111 /* FIXME: Log the error (possibly in IopInitializeDeviceNodeService) */

#112 DPRINT1("Initialization of service %S Failed (Status %x)/n",

#113 DeviceNode->ServiceName.Buffer,Status);

#114 }

#115 }

#116 }

#117 else

#118 {

#119 DPRINT("Device %wZ is disabled or already initialized/n",

#120 &DeviceNode->InstancePath);

#121 }

#122

#123 return STATUS_SUCCESS;

#124}