Patent ID: 8639895

Claim:
A data processing system comprising: a processor; and a memory protection unit (MPU) coupled to the processor and having control logic, the MPU configured to store a plurality of region descriptor entries, each region descriptor entry defining an address region, an attribute corresponding to the address region, and an attribute override control corresponding to the attribute, wherein the control logic, in response to receiving an access request for an access to an address within an address region defined by a first region descriptor entry of the plurality of region descriptor entries and within an address region defined by a second region descriptor of the plurality of region descriptor entries, is configured to: use a default policy to determine whether to apply a value of the attribute of the first region descriptor entry or to apply a value of the attribute of the second region descriptor entry for the access when the attribute override control corresponding to the attribute of the first region descriptor entry and the attribute override control corresponding to the second region descriptor entry each have a first value; apply the value of the attribute of the first region descriptor entry for the access when the attribute override control of the first region descriptor entry corresponding to the attribute has a second value; and apply the value of the attribute of the second region descriptor entry for the access when the attribute override control of the second region descriptor entry corresponding to the attribute has the second value.