CHAPTER 6 EXCEPTION PROCESSING
163
KX
: Enables 64-bit addressing in Kernel mode (0
o
32-bit, 1
o
64-bit). If this bit is set, an XTLB Refill
exception occurs if a TLB miss occurs in the Kernel mode address space.
: Enables 64-bit addressing and operation in Supervisor mode (0
o
32-bit, 1
o
64-bit). If this bit is
set, an XTLB Refill exception occurs if a TLB miss occurs in the Supervisor mode address space.
: Enables 64-bit addressing and operation in User mode (0
o
32-bit, 1
o
64-bit). If this bit is set, an
XTLB Refill exception occurs if a TLB miss occurs in the User mode address space.
: Sets and indicates the operating mode (10
o
User, 01
o
Supervisor, 00
o
Kernel).
: Sets and indicates the error level (0
o
Normal, 1
o
Error).
: Sets and indicates the exception level (0
o
Normal, 1
o
Exception).
: Sets and indicates interrupt enabling/disabling (0
o
Disabled, 1
o
Enabled).
SX
UX:
KSU
ERL
EXL
IE
Figure 6-6. Status Register Diagnostic Status Field
16
17
18
19
20
21
22
23
24
0
BEV
TS
SR
0
CH
CE
DE
1
1
1
1
1
1
1
2
BEV
: Specifies the base address of a TLB Refill exception vector and common exception vector (0
o
Normal, 1
o
Bootstrap).
: Occurs the TLB to be shut down (read-only) (0
o
Not shut down, 1
o
Shut down). This bit is used to
avoid any problems that may occur when multiple TLB entries match the same virtual address. After
the TLB has been shut down, reset the processor to enable restart. Note that the TLB is shut down
even if a TLB entry matching a virtual address is marked as being invalid (with the V bit cleared).
: Occurs a Soft Reset or NMI exception (0
o
Not occurred, 1
o
Occurred).
: CP0 condition bit (0
o
False, 1
o
True). This bit can be read and written by software only; it cannot
be accessed by hardware.
: When CE = 1, the contents of the PErr register are written to the check bits of the cache (See 6.3.10)
: Specifies whether a cache parity error causes an exception (0
o
Enable parity check, 1
o
Disable
parity check).
: Reserved for future use. Write 0 in a write operation. When this field is read, 0 is read.
TS
SR
CH
CE
DE
0
The status register has the following fields where the modes and access status are set.