| 摘要 |
A memory management unit (MMU) has cross-domain control for controlling a CPU's right to access a memory 406 for performing an operation. The MMU includes a translator 426, 436, 446, for translating a virtual address issued by the CPU 402 into a physical address 440, a data domain number (DDN) 434 and an address domain number (ADN) 438 both corresponding to a domain (a portion of the virtual address space), and a permission 442. An environment controller 462 determines if the ADN corresponding to the operation is allowed access by the CPU. The translator generates the DDN of tagged data specified by the CPU if the tagged data is a pointer. Logic 456 evaluates the permission and either stops the operation or allows it to continue. Cross-domain control logic 432 evaluates the ADN and DDN to detect the attempted flow of domain specific information as a result of the operation, can prohibit the flow of information between domains and can also prohibit the flow of control by the CPU between domains. <IMAGE>
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