| 摘要 |
Memory address space is divided into domains and instruction access control circuitry is used to detect when the memory address from which an instruction to be executed is fetched has crossed a domain boundary and in such cases to conduct a check to ensure that the instruction within the new domain is a permitted instruction of a permitted form, e.g. a permitted branch target instruction 40. If the instruction within the new domain is not a permitted instruction then an access violation response is triggered 42. To assist with backward compatibility for legacy code the permitted instruction can be arranged to be a no operation instruction other than in respect of the instruction access control circuitry. The memory address space may be a virtual memory address space associated with the memory and may comprise several domains each having respective programmable capabilities. |
