IBM powerpc 750gx User Manual
User’s Manual
IBM PowerPC 750GX and GL RISC Microprocessor
gx_04.fm.(1.2)
March 27, 2006
March 27, 2006
Exceptions
Page 155 of 377
Table 4-3. Exception Priorities
Priority
Exception
Cause
Asynchronous Exceptions (Interrupts)
0
System Reset
HRESET, POR
1
Machine Check
TEA, 60x address-parity error, 60x data-parity error, L2 ECC double-bit error, MCP, L2-tag
parity error, data-tag parity error, instruction-tag parity error, instruction-cache parity error,
data-cache parity error, or locked L2 snoop hit
parity error, data-tag parity error, instruction-tag parity error, instruction-cache parity error,
data-cache parity error, or locked L2 snoop hit
1
2
System Reset
SRESET
3
SMI
SMI (system management exception)
4
EI
INT (External Exception)
5
PFM
Performance-monitor exception
6
DEC
Decrementer exception
7
TMI
Thermal-management exception
Instruction Fetch Exceptions
0
ISI
Instruction storage exception
Instruction Dispatch/Execution Exceptions
0
IABR
Instruction address breakpoint exception
1
PI
Program exception due to:
1. Illegal instruction
2. Privileged instruction
3. Trap
3. Trap
2
SC
System call
3
FPA
Floating-point unavailable exception
4
PI
Program exception due to floating-point enabled exception
5
DSI
Data-storage exception due to eciwx, ecowx with the enable bit of the External Access Reg-
ister cleared (EAR[E] = 0) (bit 11 of DSISR)
ister cleared (EAR[E] = 0) (bit 11 of DSISR)
6
Alignment
Alignment exception due to:
•
Floating point not word aligned
•
lmw, stmw, lwarx, or stwcx not word-aligned
•
Either eciwx or ecowx not word-aligned
•
Multiple or string access with the little-endian bit set.
•
dcbz to write-through or cache-inhibited page or cache is disabled.
7
DSI
Data-storage exception due to a block-address-translation (BAT) page-protection violation
8
DSI
Data-storage exception due to:
•
Any access except cache operations to a segment where SR[T] = 1
•
An access that crosses from an SR[T] = 0 segment to an SR[T} = 1 segment
These exceptions are indicated by DSISR[5] = 1.
9
DSI
Data-storage exception due to a translation lookaside buffer (TLB) page-protection violation
10
DSI
Data-storage exception due to a Data Address Breakpoint Register (DABR) address match
Post Instruction Execution Exceptions
11
Trace
Trace exception due to:
MSR[SE] = 1 or (MSR[BE] = 1 for branches
MSR[SE] = 1 or (MSR[BE] = 1 for branches
1. Even though DSISR(5) and DSISR(11) are set by different priority exceptions, both bits can be set at the same time.