11.3 R4000 Cache Description
Figure 11-7 shows the physical address (PA) index into the secondary cache. The secondary cache ranges in size from 128 Kbytes to 4 Mbytes, and the number of physical address bits used to index the cache depends upon the cache size. For instance, PA(16:4) accesses the tags in a 128-Kbyte secondary cache with 4-word lines; PA(21:5) accesses the tags in a 4-Mbyte secondary cache with 8-word lines.
The processor always uses PA(35:17) from the secondary cache, regardless of the S-cache size. This makes it important to initialize all secondary cache tag address bits with a valid physical address, regardless of the size of the S-cache.
Figure 11-7 Secondary Cache Data and Tag Organization
Copyright 1996, MIPS Technologies, Inc. -- 21 MAR 96
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