Device Objects and Device Extensions

Both the I/O Manager and a driver need to know what's going on with an I/O device at all times. Device objects make this possible by keeping information about the device's characteristics and state. There is one device object for each virtual, logical, and physical device on the system. The life cycle of a device object is shown below.

  1. The DriverEntry routine creates a device object for each of its devices. For WDM drivers, the Device object is created by the AddDevice Plug and Play routine.

  2. The I/O Manager uses a back-pointer in the device object to locate the corresponding driver object. There it can find driver routines to operate on I/O requests. It also maintains a queue of current and pending IRPs attached ...

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