
4-24
MPC603e & EC603e RISC Microprocessors User's Manual
MOTOROLA
When a DSI exception is taken, instruction execution for the handler begins at offset
0x00300 from the physical base address indicated by MSR[IP].
The architecture permits certain instructions to be partially executed when they cause a DSI
exception. These are as follows:
Load multiple or load string instructions—Some registers in the range of registers to
be loaded may have been loaded.
Store multiple or store string instructions—Some bytes of memory in the range
addressed may have been updated.
In these cases, the number of registers and amount of memory altered are instruction- and
boundary-dependent. However, memory protection is not violated. Furthermore, if some of
the data accessed is in direct-store space (SR[T] = 1) and the instruction is not supported
for direct-store accesses, the locations in direct-store space are not accessed.
For update forms, the update register (
r
A) is not altered.
Table 4-11. DSI Exception—Register Settings
Register
Setting Description
SRR0
Set to the effective address of the instruction that caused the exception.
SRR1
0–15
16–31 Loaded with bits 16–31 of the MSR
Cleared
MSR
POW 0
TGPR0
ILE
IP
—
—
EE
PR
FP
1
ME
0
0
0
—
FE0
2
0
SE
BE
FE1
2
0
0
0
IR
DR
RI
LE
0
0
0
Set to value of ILE
DSISR
0
1
Set if a load or store instruction results in a direct-store error exception.
Set by the data TLB miss exception handler if the translation of an attempted access is not
found in the primary hash table entry group (HTEG), or in the rehashed secondary HTEG, or in
the range of a DBAT register; otherwise cleared.
Cleared
Set if a memory access is not permitted by the page or BAT protection mechanism; otherwise
cleared.
Set if the
lwarx
or
stwcx.
instruction is attempted to direct-store space.
Set for a store operation and cleared for a load operation.
7–31 Cleared
2–3
4
5
6
DAR
Set to the effective address of a memory element as described in the following list:
A byte in the first word accessed in the page that caused the DSI exception, for a byte, half word, or
word memory access.
A byte in the first word accessed in the BAT area that caused the DSI exception for a byte, half
word, or word access to a BAT area.
A byte in the block that caused the exception for
icbi
,
dcbz
,
dcbst
,
dcbf
,
or
dcbi
instructions.
Any EA in the memory range addressed (for direct-store exceptions).
Notes:
1. The floating-point available bit is always cleared to 0 on the EC603e microprocessor.
2. FE0 and FE1 are not supported on the EC603e microprocessor.