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Developing Drivers with the Windows Driver Foundation: WDF Fundamentals

Plug and Play and Power Management

Seamless and robust handling of Plug and Play and power events is critically important to system reliability and a good user experience. A primary WDF design goal was to simplify the implementation of Plug and Play and power management support and make this support available to both UMDF and KMDF drivers.

WDF drivers are not required to implement the complicated logic that is required to track Plug and Play and power state. Internally, the framework supports a set of state machines that manage Plug and Play and power state for WDF drivers. The framework notifies WDF drivers of changes in Plug and Play and power state through a series of events, each of which maps directly to device-specific actions that the driver can perform.

The framework provides default processing for every Plug and Play and power event. This approach vastly reduces the number of decisions that a WDF driver is required to make—especially during power transitions. WDF drivers contain much less Plug and Play and power management code than WDM drivers. Some WDF software drivers do not require any Plug and Play and power management code at all.

Chapter 7 provides details about how WDF handles Plug and Play and power state changes.