5.5 Secondary Cache Tag

SCTag(1:0), Cache Block State


The lower two bits of the secondary cache tag, SCTag(1:0), contain the cache block state, which can be Invalid, Shared, CleanExclusive, or DirtyExclusive as shown in Table 5-4.

Table 5-4 Secondary Cache Tag State Field Encoding

Since the secondary cache tags are updated immediately for stores to the primary data cache, and all caches use a write back protocol, the data in the secondary cache may not always be consistent with data in the primary cache even though the tags always reflect the correct state of a secondary cache block.




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


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