Memory Management Unit
11-18 MPC823e REFERENCE MANUAL MOTOROLA
MEMORY MANAGEMENT
11
UNIT
TWAM—Tablewalk Assist Mode
0 = 1K subpage hardware assist.
1 = 4K page hardware assist.
PPCS—Privilege/Problem State Compare Mode
0 = Ignore problem/privilege state during address compare.
1 = Consider problem/privilege state according to MD_RPN[24:27].
Bits 7–18—Reserved
These bits are reserved and must be set to 0. Ignored on write and returns a 0 on read.
DTLB_INDX—Data TLB Index
This field acts as a pointer to the data TLB entry to be loaded. It is automatically
decremented at every data translation lookaside buffer update.
Bits 24–31—Reserved
These bits are reserved and must be set to 0. Ignored on write and returns a 0 on read.
11.6.1.3 MMU CURRENT ADDRESS SPACE ID REGISTER. The MMU current address
space ID (M_CASID) register is used to compare the current effective address with the ASID
field in the TLB entry when searching for a matching entry.
Bits 0–27—Reserved
These bits are reserved and must be set to 0. Ignored on a write.
CASID—Current Address Space ID
This field is compared to the ASID field of a TLB entry to qualify a match.
M_CASID
BIT 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
FIELD RESERVED
RESET —
R/W R
ADDR SPR 793
BIT 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
FIELD RESERVED CASID
RESET ——
R/W R R/W
ADDR SPR 793
NOTE: — = Undefined.
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