---
title: UserStartController
framework: SCSIControllerDriverKit
role: symbol
role_heading: Instance Method
path: scsicontrollerdriverkit/iouserscsiparallelinterfacecontroller/userstartcontroller
---

# UserStartController

Starts the controller in response to a call from the framework.

## Declaration

```occ
virtual kern_return_t UserStartController();
```

## Return Value

Return Value A value that indicates the result of initialization. kIOReturnSuccess indicates success. For error definitions, see IOKit Constants.

## Discussion

Discussion The framework always calls UserStartController before sending any requests to the driver for execution. The framework calls this method after UserInitializeController to start the services that the specific host bus adapter (HBA) dext driver provides. After completing this call, all services provided by the HBA driver are available to the client. The following sample implementation of UserStartController sets its local power state to kIOServicePowerCapabilityOn, then calls a hypothetical EnableReplyInterrupt() convenience function. Next, it enables the interrupt dispatch source, and returns kIOReturnSuccess. Signaling success like this indicates to the kernel that the dext is now up and ready to serve I/O. kern_return_t IMPL ( ExampleSCSIDext, UserStartController ) {          kern_return_t ret = kIOReturnError;          ivars->fCurrentPowerState = kIOServicePowerCapabilityOn;

// Enable interrupts on the hardware     EnableReplyInterrupt ( );          // Enable interrupt event source     ret = ivars->fIntSource->SetEnable ( true );     __Require ( ( kIOReturnSuccess == ret ), Exit );

… }

## See Also

### Managing controllers

- [UserInitializeController](scsicontrollerdriverkit/iouserscsiparallelinterfacecontroller/userinitializecontroller.md)