This disclosure provides a method for tagging control information associated with a physical address in a processing system, including setting a hardware tag for the control information, the hardware tag being invisible to a software system in the processing system; joining the hardware tag with the physical address to form a compound physical address, the hardware tag including M bits carried by a dedicated hardware tag control line, the physical address including N bits carried by a physical address bus, M and N being positive integers; and tagging the control information with the hardware tag in the compound physical address.