CHAPTER 3 CP0 REGISTERS
User’s Manual U14272EJ3V0UM
68
Table 3-1. CP0 Registers
Number
Register
Usage
Description
0
Index
Memory management
Programmable pointer to TLB array
1
Random
Memory management
Pseudo-random pointer to TLB array (read only)
2
EntryLo0
Memory management
Lower half of TLB entry for even VPN
3
EntryLo1
Memory management
Lower half of TLB entry for odd VPN
4
Context
Exception processing
Pointer to kernel virtual PTE in 32-bit mode
5
PageMask
Memory management
Page size specification
6
Wired
Memory management
Number of wired TLB entries
7
−
−
Reserved for future use
8
BadVAddr
Exception processing
Virtual address where the most recent error occurred
9
Count
Exception processing
Timer count
10
EntryHi
Memory management
Higher half of TLB entry (including ASID)
11
Compare
Exception processing
Timer compare value
12
Status
Exception processing
Status indication
13
Cause
Exception processing
Cause of last exception
14
EPC
Exception processing
Exception Program Counter
15
PRId
Memory management
Processor revision identifier
16
Config
Memory management
Configuration (memory system modes) specification
17
LLAddr
Note1
Memory management
Physical address for self diagnostics
18
WatchLo
Exception processing
Memory reference trap address low bits
19
WatchHi
Exception processing
Memory reference trap address high bits
20
XContext
Exception processing
Pointer to kernel virtual PTE in 64-bit mode
21 to 25
−
−
Reserved for future use
26
Parity Error
Note2
Exception processing
Cache parity bits
27
Cache Error
Note2
Exception processing
Index and status of cache error
28
TagLo
Memory management
Lower half of cache tag
29
TagHi
Memory management
Higher half of cache tag
30
ErrorEPC
Exception processing
Error Exception Program Counter
31
−
−
Reserved for future use
Notes1. This register is defined to maintain compatibility with the V
R
4000 and V
R
4400. This register is meaningless
during normal operations.
2. This register is defined to maintain compatibility with the V
R
4100. This register is not used in the V
R
4181
hardware.