* @private: private data to associate with the pipe, for the caller's use
* @ops: operations defining the behavior of the pipe: upcall, downcall,
* release_pipe, and destroy_msg.
* @private: private data to associate with the pipe, for the caller's use
* @ops: operations defining the behavior of the pipe: upcall, downcall,
* release_pipe, and destroy_msg.