SIZE_T MmSizeOfMdl( IN PVOID Base, IN SIZE_T Length ); Routine Description: This function returns the number of bytes required for an MDL for a given buffer and size. Arguments: Base - Supplies the base virtual address for the buffer. Length - Supplies the size of the buffer in bytes. Return Value: Returns the number of bytes required to contain the MDL. Environment: Kernel mode. Any IRQL level.