Книга: Microsoft Windows Embedded CE 6.0 Exam Preparation Kit
Registry Keys Related to Loaded Device Drivers
Registry Keys Related to Loaded Device Drivers
Apart from configurable registry entries in driver-specific subkeys, Device Manager also maintains dynamic registry information in subkeys for loaded drivers under the HKEY_LOCAL_MACHINEDriversActive key. The subkeys correspond to numerical values that the operating system assigns dynamically and increments for each driver until the system is restarted. The number does not signify a particular driver. For example, if you unload and reload a device driver, the operating system assigns the next number to the driver and does not reuse the previous subkey. Because you cannot ensure a reliable association between the subkey number and a particular device driver, you should not edit the driver entries in the HKEY_LOCAL_MACHINEDriversActive key manually. However, you can create, read, and write driver-specific registry keys at load time in a driver's XXX_Init function because Device Manager passes the path to the current DriversActive subkey to the stream driver as the first parameter. The driver can open this registry key using OpenDeviceKey.
Table 6-4 lists typical entries that the subkeys under DriversActive can contain.
Table 6-4 Registry entries for device drivers under the HKEY_LOCAL_MACHINEDriversActive key
| Registry Entry | Type | Description |
|---|---|---|
| Hnd | REG_DWORD | The handle value for the loaded device driver. You can obtain this DWORD value from the registry and pass it in a call to DeactivateDevice in order to unload the driver. |
| BusDriver | REG_SZ | The name of the driver's bus. |
| BusName | REG_SZ | The name of the device's bus. |
| DevID | A unique device identifier from Device Manager. | |
| FullName | REG_SZ | The name of the device if used with the $device namespace. |
| Name | REG_SZ | The driver's legacy device file name including index, if a prefix is specified (not present for drivers that do not specify a prefix). |
| Order | REG_DWORD | The same order value as in the driver's registry key. |
| Key | REG_SZ | The registry path to the driver's registry key. |
| PnpId | REG_SZ | The Plug and Play identifier string for PCMCIA drivers. |
| Sckt | REG_DWORD | For PCMCIA drivers, describes the current socket and function of the PC card. |
NOTE
Checking the Active key
By calling the RequestDeviceNotifications function with a device interface GUID of DEVCLASS_STREAM_GUID, an application can receive messages from Device Manager to identify loaded stream drivers programmatically. RequestDeviceNotifications supersedes the EnumDevices function.
Оглавление книги
- Device Driver Load Procedure
- 11.7 Soft Timers and Timer Related Operations
- Creating and Deleting Device Objects
- Installing Proprietary Video Drivers
- Remote Registry Editor
- Introduction to Serial Devices
- Devices
- The Disk as a Storage Device
- Chapter 8. Device Driver Basics
- 18.2.5. Block devices
- 8.1. Device Driver Concepts
- 8.1.2. Device Driver Architecture