| 摘要 |
A memory-type value identifying the type of memory contained with a range of memory locations is explicitly stored within a microprocessor. Prior to processing a memory micro-instruction such as a load or store, the memory-type is determined for the memory location identified by the memory micro-instruction. Once the memory-type is known the memory micro-instruction is processed in accordance with any one of a number of processing protocols including write-through processing, write-back processing, write-protect processing, restricted-cacheability processing, uncacheable speculatable write-combining processing, or uncacheable processing. By providing memory-type information explicitly within the microprocessor, the type of memory identified by a micro-instruction is known before the micro-instruction is processed. Accordingly, the protocol by which the micro-instruction is processed may be efficiently tailored to the memory-type. For example, if the memory location identified by the micro-instruction is known to be uncacheable, a data cache unit is bypassed and external memory is accessed directly. In an exemplary embodiment, the microprocessor is an out-of-order microprocessor capable of generating speculative memory micro-instruction. Also, the microprocessor may be only one of a number of microprocessors within a multiprocessor system. |
