Supporting Special Files

Special files include paging files, dump files, and hibernation files. If the target device for your driver is a storage device that the system might use for these files, the driver must do the following:

• Call WdfDeviceSetSpecialFileSupport to enable or disable support for each type of special file. (Each driver's support for special files is disabled by default.)

  A bus driver that enumerates child devices should also call WdfDeviceSetSpecialFileSupport for each child device that can support special files.

• Call WdfDeviceAddDependentUsageDeviceObject, if one device is dependent on another device when supporting special files.

• Optionally provide an EvtDeviceUsageNotification or (starting in KMDF 1.11) EvtDeviceUsageNotificationEx callback function, so the driver will be notified when a special file is created or removed.

If your driver calls WdfDeviceSetSpecialFileSupport for a device, and if a special file is open on the device, the framework does not allow the PnP manager to remove or stop the device.

After a driver has called WdfDeviceAddDependentUsageDeviceObject, it can call WdfDeviceRemoveDependentUsageDeviceObject to remove a device's dependency on another device.