Highlights

This chapter looks at Windows Management Instrumentation (WMI), the first of two methods of reporting management information to system administrators. The alternative NT events for NT 3.51, NT 4, and Windows 2000 drivers is covered in the next chapter. NT events are not recorded in Windows 98.

Windows Management Instrumentation is supposed to work in most Windows platforms. However, it did not work for me in Windows 98. As well as reporting information and firing events, WMI lets users set values that control the operation of a device or even invoke driver methods.

If possible, a driver should support the "WMI extensions for WDM". Although not mandatory, it can make it easier to debug or control your driver in the field. WMI support is required for some system functions (e.g., if you want to support user control of Power Management options in the device properties tab). If you do not support WMI, please provide a default WMI IRP handler such as in the Wdm1SystemControl routine.

The example Wdm3 driver builds on the Wdm2 driver, adding WMI and NT event support. It handles the standard MSPower_DeviceEnable WMI data block and defines its own custom WMI data block called Wdm3Information. The Wdm3Information data block returns three pieces of information to a user for each Wdm3 device: the length of the buffer, the first DWORD of the buffer contents, and the symbolic link name of the device.

I was not able to get these two further...