
CHAPTER 4 MEMORY MANAGEMENT SYSTEM
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(1) TLB misses
If there is no TLB entry that matches the virtual address, a TLB Refill (miss) exception occurs
access control bits (D and V) indicate that the access is not valid, a TLB Modified or TLB Invalid
exception occurs. If the C bit is 010, the retrieved physical address directly accesses main memory,
bypassing the cache.
Note
. If the
Note
See Chapter 5 for details of the TLB Miss exception.
(2) TLB instructions
The instructions used for TLB control are described below.
(a) Translation lookaside buffer probe (TLBP)
The translation lookaside buffer probe (TLBP) instruction loads the Index register with a TLB number
that matches the content of the EntryHi register. If there is no TLB number that matches the TLB entry,
the highest-order bit of the Index register is set.
(b) Translation lookaside buffer read (TLBR)
The translation lookaside buffer read (TLBR) instruction loads the EntryHi, EntryLo0, EntryLo1, and
PageMask registers with the content of the TLB entry indicated by the content of the Index register.
(c) Translation lookaside buffer write index (TLBWI)
The translation lookaside buffer write index (TLBWI) instruction writes the contents of the EntryHi,
EntryLo0, EntryLo1, and PageMask registers to the TLB entry indicated by the content of the Index
register.
(d) Translation lookaside buffer write random (TLBWR)
The translation lookaside buffer write random (TLBWR) instruction writes the contents of the EntryHi,
EntryLo0, EntryLo1, and PageMask registers to the TLB entry indicated by the content of the Random
register.