
MOTOROLA
Chapter 5. Exceptions
5-19
Exception Definitions
5.5.1
Reset Exceptions (0x00100)
The system reset exception is a nonmaskable, asynchronous exception signaled to the G2
core either through the assertion of the reset signals (core_sreset or core_hreset) or
internally during the power-on reset (POR) process. The assertion of the soft reset signal,
core_sreset, as described in Section 8.3.10.2, “Soft Reset (core_sreset)—Input,” causes the
system reset exception to be taken and the physical base address of the handler is
determined by the MSR[IP] bit.
The assertion of the hard reset signal, core_hreset, as described in Section 8.3.10.1, “Hard
Reset (core_hreset)—Input,” causes the system reset exception to be taken.
Note that there are some byte ordering precautions necessary when coming out of reset in
big-endian mode and switching to little-endian mode. The following sections describe the
differences between a hard and soft reset and the byte ordering implications for reset
exception handling.
5.5.1.1
Hard Reset and Power-On Reset
As described in Section 5.1.2, “Summary of Front-End Exception Handling,” the hard reset
exception is a nonrecoverable, nonmaskable asynchronous exception. When core_hreset is
asserted or at power-on reset (POR), the G2 core immediately branches to the address
determined by the state of the core_msrip signal, as described in Table 5-10, without
attempting to reach a recoverable state.
Instruction
address
breakpoint
0
0
—
0
0
0
—
0
0
0
0
—
—
0
0
0
ILE
System
management
interrupt
0
0
—
0
0
0
—
0
0
0
0
—
—
0
0
0
ILE
Note:
0
1
ILE
—
Reserved bits are read as if written as 0.
Bit is cleared.
Bit is set.
Bit is copied from the ILE bit in the MSR.
Bit is not altered.
1
G2_LE core only.
Table 5-9. MSR Setting Due to Exception (continued)
Exception Type
MSR Bit
POW
TGPR
ILE
EE
PR
FP
ME
FE0
SE
BE
FE1 CE
1
IP
IR
DR
RI
LE
F
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