Developing Drivers with the Windows® Driver Foundation

Object Context Areas

The object context area is a driver-defined storage area for data that the driver uses with a particular object. UMDF drivers and KMDF drivers tend to use object context areas in different ways:

• A UMDF driver typically stores context data in a driver callback object, but can create a context area in a framework object if necessary.

• KMDF drivers do not create callback objects and therefore typically create and use a context area in a framework object.

UMDF Object Context Data

UMDF drivers can store context data that pertains to a particular object in either of two ways:

• In data members of the callback object.

• In a separate context area that the driver defines and assigns to the framework object.

The best location for the context data ...