何时PNP管理器调用AddDevice?（《Programming the Microsoft Windows Driver Model》）

          《Programming the Microsoft Windows Driver Model》中，第二章第二节〈DriverEntry例程〉中，说：
extern "C"
NTSTATUS
DriverEntry(IN PDRIVER_OBJECT DriverObject, IN PUNICODE_STRING RegistryPath)
{
DriverObject->DriverUnload = DriverUnload;
DriverObject->DriverExtension->AddDevice = AddDevice;
DriverObject->DriverStartIo = StartIo;
DriverObject->MajorFunction[IRP_MJ_PNP] = DispatchPnp;
DriverObject->MajorFunction[IRP_MJ_POWER] = DispatchPower;
DriverObject->MajorFunction[IRP_MJ_SYSTEM_CONTROL] = DispatchWmi;
servkey.Buffer = (PWSTR) ExAllocatePool(PagedPool, RegistryPath->Length + sizeof(WCHAR));
if (!servkey.Buffer)
return STATUS_INSUFFICIENT_RESOURCES;
servkey.MaximumLength = RegistryPath->Length + sizeof(WCHAR);
RtlCopyUnicodeString(&servkey, RegistryPath);
return STATUS_SUCCESS;
}

你应当就意到，AddDevice例程是通过DriverExtension被登记的。这样的话，AddDevice势必对于外部不可见。也就是说，PNP管理器不应当见到它。


但，后一节的开关（AddDevice例程）又说：
          在前一节中，我讲述了当WDM驱动程序被第一次装入时如何初始化。通常，一个驱动程序可以被多个设备利用。WDM驱动程序有一个特殊的AddDevice函数，PnP管理器为每个设备实例调用该函数。该函数的原型如下。。。

请问，PNP管理器如何看到AddDevice呢？真是奇怪。

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仔细看了书，原来Extension不是自定义的结构，该 问题无效，请管理员DELETE，我删除不了

PDRIVER_EXTENSION DriverExtension
Pointer to the driver extension. The only accessible member of the driver extension is DriverExtension->AddDevice, into which a driver's DriverEntry routine stores the driver's AddDevice routine.


唯一可见的...