Memory Management Unit That Applies Rules Based on Privilege Identifier

摘要

A memory management and protection system that manages memory access requests from a number of requestors. Memory accesses are allowed or disallowed based on the privilege level of the master, usually a CPU originating the request based on a Privilege Identifier that accompanies each memory access request. Deputy masters such as DMA controllers inherit the Privilege Identifier of the originating master. An extended memory controller selects the appropriate set of segment registers based on the Privilege Identifier to insure that the request is compared to and translated by the segment register associated with the master originating the request.