Multi-region default memory map
AssigneeArm Limited
InventorsSimon Axford, Simon John Craske, Paul Kimelman
Life of this patent
Estimating the term…
Abstract
A data processing system is provided with a programmable memory protection unit 10 defining a plurality of programmable memory regions 2, 4, 6, 8 each with associated programmable memory attributes. A default memory protection unit 22 is provided and defines a plurality of default memory regions a, b, c, d, e each with associated default memory attributes. If a miss occurs in the programmable memory protection unit 10, and the memory access is a privileged level memory access, then the default memory protection unit 22 will return default memory attributes for that memory request.
Claims16
An apparatus for processing data, said apparatus comprising:
- a source of memory access requests to respective memory addresses within a memory address space;
- a programmable memory protection unit configured to store programmable data defining a plurality of programmable memory regions within said memory address space having associated programmable memory attributes, said programmable memory protection unit being operable to receive a memory access request to a target memory address from said source and, if said target address lies within one or more of said plurality of programmable memory regions, then to return an associated programmable memory attribute for said target address;
- and
- a default memory protection unit hard-wired to define a plurality of default memory regions within said memory address space having associated default memory attributes, said default memory protection unit being operable to receive said memory request to said target memory address from said source and, if said target address does not lie within one or more of said plurality of programmable memory regions, then to return an associated default memory attribute for said target address, wherein said default memory protection unit is controllable to be enabled or disabled and if said default memory protection unit is disabled, then if said target address does not lie within one or more of said plurality of programmable memory regions, then a memory protection violation signal is generated.
A method of processing data, said method comprising the steps of:
- generating memory access requests to respective memory addresses within a memory address space;
- storing programmble data within a programmable memory protection unit defining a plurality of programmable memory regions within said memory address space having associated programmable memory attributes;
- receiving a memory access request to a target memory address in said programmable memory protection unit and, if said target address lies within one or more of said plurality of programmable memory regions, then returning an associated programmable memory attribute for said target address;
- storing default data within a default memory protection unit hard-wired to define a plurality of default memory regions within said memory address space having associated default memory attributes;
- and
- receiving a memory request to a target memory address in said default memory protection unit and, if said target address does not lie within one or more of said plurality of programmable memory regions, then returning an associated default memory attribute for said target address, wherein said default memory protection unit is controllable to be enabled or disabled and if said default memory protection unit is disabled, then if said target address does not lie within one or more of said plurality of programmable memory regions, then a memory protection violation signal is generated.
Dependencies are inferred from the claim text.