# UserCreateTargetForID Creates the specified target. ``` virtual kern_return_t UserCreateTargetForID(SCSIDeviceIdentifier targetID, OSDictionary *targetDict); ``` ## Parameters `targetID` The ID of the target to create. `targetDict` An containing all of the target properties. ## Return Value A value that indicates the result of target creation. indicates success. For error definitions, see . ## Discussion Your driver extension class calls this method to create a new target for the `targetID`. The framework creates the new target before the call returns. As part of the [`UserCreateTargetForID`](/documentation/SCSIControllerDriverKit/IOUserSCSIParallelInterfaceController/UserCreateTargetForID) call, the kernel calls several APIs like [`UserInitializeTargetForID`](/documentation/SCSIControllerDriverKit/IOUserSCSIParallelInterfaceController/UserInitializeTargetForID) which run on the default dispatch queue of the dext. Synchronously calling [`UserCreateTargetForID`](/documentation/SCSIControllerDriverKit/IOUserSCSIParallelInterfaceController/UserCreateTargetForID) from the default dispatch queue blocks the default dispatch queue until [`UserCreateTargetForID`](/documentation/SCSIControllerDriverKit/IOUserSCSIParallelInterfaceController/UserCreateTargetForID) finishes. Subsequent calls from the kernel like [`UserInitializeTargetForID`](/documentation/SCSIControllerDriverKit/IOUserSCSIParallelInterfaceController/UserInitializeTargetForID) won’t have a chance to run on the default queue, leading to a deadlock. You can avoid this problem by calling [`UserCreateTargetForID`](/documentation/SCSIControllerDriverKit/IOUserSCSIParallelInterfaceController/UserCreateTargetForID) from an asynchronous handler function. Start by creating an async handler function for your custom dext class in its `iig` file, as shown below: ```objc virtual void AsyncEventHandler ( OSAction * action TARGET, uint32_t targetID ) = 0; virtual void AsyncCreateTargetForID ( OSAction * action, uint32_t targetID ) TYPE ( ExampleSCSIDext::AsyncEventHandler ) QUEUENAME ( AuxiliaryQueue ); ``` This handler function can then call [`UserCreateTargetForID`](/documentation/SCSIControllerDriverKit/IOUserSCSIParallelInterfaceController/UserCreateTargetForID): ```objc void IMPL ( MyCustomService, AsyncCreateTargetForID ) { kern_return_t ret; … ret = UserCreateTargetForID (targetID, NULL); … } ``` Then you can call this handler in [`UserStartController`](/documentation/SCSIControllerDriverKit/IOUserSCSIParallelInterfaceController/UserStartController): ```objc kern_return_t IMPL ( MyCustomService, UserStartController ) { … ret = CreateActionAsyncCreateTargetForID ( sizeof ( void * ), &ivars->fAsyncEventHandler ); assert ( kIOReturnSuccess == ret ); AsyncEventHandler ( ivars->fAsyncEventHandler, targetID ); … } ``` This implementation ensures [`UserStartController`](/documentation/SCSIControllerDriverKit/IOUserSCSIParallelInterfaceController/UserStartController) calls the event handler asynchronously, which frees up the default dispatch queue for subsequent calls. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)