
CHAPTER 2 V
R
4120A
Preliminary User’s Manual S15543EJ1V0UM
159
Figure 2-61. Common Exception Handling (1/2)
(a) Handling Exceptions other than Cold Reset, Soft Reset, NMI, and TLB/XTLB Refill (Hardware)
BD bit
←
1
EPC
←
PC
−
4
EXL
←
1
Kernel mode is set and interrupts
are disabled.
= 0 (Normal) = 1 (bootstrap)
Check for multiple exceptions
Kernel mode is set and interrupts are
disabled.
•
• EntryHi and X/Context registers are set only
when a TLB Refill, TLB Invalid, or TLB
Modified exception occurs.
X/Context
←
VPN2
Entry Hi
←
VPN2, ASID
Set Cause register (ExcCode, CE)
To guideline to common exception handler
Start
Yes
EXL = 1?
(SR1)
No
NoYes
Instruction
in branch delay
slot?
BEV
PC
←
FFFF FFFF BFC0 0200H +180H
(Unmapped, uncached space)
M16 = 1?
(config20)
PC
←
FFFF FFFF 8000 0000H +180H
(Unmapped, cacheable space)
No
Instruction
in delay slot?
BD bit
←
1
EPC
←
PC
−
4
EPC
←
EIM
BD bit
←
0
EPC
←
PC
EPC
←
EIM
NoYes
Yes
BD bit
←
0
EPC
←
PC
•
BadVAddr is set only when a TLB Refill, TLB
Invalid, or TLB Modified exception occurs
(BadVAddr is not set when a Bus Error exception
occurs).
•
Remark The interrupts can be masked by setting the IE or IM bit.
The Watch exception can be set to pending state by setting the EXL bit to 1.
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