Create an IOMemoryDescriptor to describe one virtual range of the kernel task.
The virtual address of the first byte in the memory.
The length of memory.
An I/O direction to be associated with the descriptor, which may affect the operation of the prepare and complete methods on some architectures.
The created IOMemoryDescriptor on success, to be released by the caller, or zero on failure.
This method creates and initializes an IOMemoryDescriptor for memory consisting of a single virtual memory range mapped into the kernel map. This memory descriptor needs to be prepared before it can be used to extract data from the memory described.