6. System Interface Operations

6.22 Support for a Directory-Based Coherency Protocol


Some system designs implement a directory-based coherency protocol.

For such systems, the processor provides the processor eliminate request cycle. If the PrcElmReq mode bit is asserted, the processor issues a processor eliminate request whenever it intends to eliminate a Shared, CleanExclusive, or DirtyExclusive block from the secondary cache. During the address cycle of the processor eliminate request, the physical address and the secondary cache block former state are provided. The external agent may then use this information to maintain an external directory structure.




Copyright 1995, MIPS Technologies, Inc. -- 29 JAN 96


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