The IoCallDriver routine sends an IRP to the driver associated with a specified device object.
- DeviceObject [in]
Pointer to a device object, representing the target device for the requested I/O operation.
- Irp [in, out]
Pointer to the IRP.
IoCallDriver returns the NTSTATUS value that a lower driver set in the I/O status block for the given request, or STATUS_PENDING if the request was queued for additional processing.
Before calling IoCallDriver, the calling driver must set up the I/O stack location in the IRP for the target driver. For more information, see Passing IRPs Down the Driver Stack.
IoCallDriver assigns the DeviceObject input parameter to the DeviceObject member of the IO_STACK_LOCATION structure for the driver being called.
An IRP passed in a call to IoCallDriver becomes inaccessible to the higher-level driver, unless the higher-level driver has called IoSetCompletionRoutine to set up an IoCompletion routine for the IRP. If it has, the IRP input to the IoCompletion routine has its I/O status block set by the lower drivers, and all lower-level drivers' I/O stack locations are filled with zeros.
Drivers for Windows Server 2003, Windows XP, and Windows 2000 must use PoCallDriver rather than IoCallDriver to pass power IRPs (IRP_MJ_POWER). For more information, see Calling IoCallDriver vs. Calling PoCallDriver.