User’s Manual
PPC440x5 CPU Core Preliminary
Page 136 of 589 mmu.fm.
September 12, 2002
Address Translation Fields
1 0:21 RPN
Real Page Number (variable size, from 4 - 22 bits)
Bits 0:n–1 of the RPN field are used to replace bits 0:n–1 of the effective address to produce a
portion of the real address for the storage access (where n = 32–log2(pagesize inbytes) and
pagesize is specified by the SIZE field of the TLB entry). Software must set unused low-order
RPN bits (that is, bits n:21) to 0. SeeAddress Translation on page 140 andTable 5-3 on
page142.
1 22:23 PAR1
Parity for TLB word 1 (2 bits)
The PAR1 field reads the parity bits associated with TLB word 1. These bits will be loaded into a
GPRas a result of a tlbre, but are ignored when executing a tlbwe, since the parity to be writ-
ten is calculated by the processor hardware.
1 28:31 ERPN Extended Real Page Number (4 bits)
The4-bit ERPN field are prepended to the rest of the translated address to form a total of a 36-bit
(64 GB) real address. SeeAddress Translation on page 140 andTable 5-3 on page 142.
Storage Attribute Fields
2 0:1 PAR2
Parity for TLB word 2(2 bits)
The PAR2 field reads the parity bits associated with TLB word 2. These bits will be loaded into a
GPRas a result of a tlbre, but are ignored when executing a tlbwe, since the parity to be writ-
ten is calculated by the processor hardware..
216U0
User-Definable Storage Attribute 0(1 bit) See User-Definable (U0–U3) on page147.
Specifiesthe U0 storage attribute for the page associated with the TLB entry. The function of this
storage attribute is system-dependent, and has no effect within the PPC440x5 core.
217U1
User-Definable Storage Attribute 1(1 bit) SeeUser-Definable (U0–U3) on page 147.
Specifiesthe U1 storage attribute for the page associated with the TLB entry. The function of this
storage attribute is system-dependent, but the PPC440x5 core can be programmed to use this
attribute to designate a memory page as containingtransient data and/or instructions (see
Instruction and Data Caches on page95).
218U2
User-Definable Storage Attribute 2(1 bit) SeeUser-Definable (U0–U3) on page 147.
Specifiesthe U2 storage attribute for the page associated with the TLB entry. The function of this
storage attribute is system-dependent, but the PPC440x5 core can be programmed to use this
attributeto specify whether or not stores that miss in the data cache should allocate the line in the
data cache (seeInstruction and Data Caches on page 95).
219U3
User-Definable Storage Attribute 3(1 bit) SeeUser-Definable (U0–U3) on page 147.
Specifiesthe U3 storage attribute for the page associated with the TLB entry. The function of this
storage attribute is system-dependent, and has no effect within the PPC440x5 core.
220W
Write-Through(1 bit) SeeWrite-Through (W) on page 145.
0 The page is not write-through (that is, the page is copy-back).
1 The page is write-through.
221I
Caching Inhibited (1 bit) SeeCaching Inhibited (I) on page 145.
0 The page is not caching inhibited (that is, the page is cacheable).
1 The page is caching inhibited.
Table5-1. TLB Entry Fields (continued)
TLB
Word Bit Field Description