Developing Drivers with the Windows® Driver Foundation

Introduction to Plug and Play and Power Management

Windows and WDM expose a complicated model for Plug and Play and power management that depends on the driver to keep track of both the state of its device and the state of the system, thus in effect implementing its own informal state machine. WDM drivers must know which Plug and Play and power requests to handle in each state and which operations to perform in response to those requests. Some requests require the driver to perform one operation if the device is powered up and a different operation if it is not. Other requests require no driver action at all, but the driver must nevertheless include code that parses the request and checks the current device and system state to determine whether ...