
MOTOROLA
Chapter 5. Exceptions
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Exception Definitions
Register settings for this exception are described in Chapter 6, “Exceptions,” in the
Programming Environments Manual.
When a decrementer exception is taken, instruction execution for the handler begins at
offset 0x00900 from the physical base address indicated by MSR[IP].
5.5.10 Critical Interrupt Exception (0x00A00)—G2_LE Only
A critical interrupt is signaled to the G2_LE core by the assertion of the core_int signal as
described in Section 8.3.9.2, “Critical Interrupt (core_cint)—Input: G2_LE Core-Only.”
The interrupt may not be recognized if a higher priority exception occurs simultaneously or
if the MSR[CE] bit is cleared when core_cint is asserted.
The following events occur when the G2_LE recognizes the assertion of core_cint:
Multi-cycle instructions not in the completion stage are terminated
Outstanding load or store instructions that have not been completed are terminated
Any outstanding page table search activity is terminated
The effective address for resuming program execution is saved into CSRR0
The contents of MSR are saved into CSRR1
The MSR register is loaded with all zeros except the IP, ILE, and ME bits which
remain unchanged
Exception processing starts at offset value 0x00A00 from the physical base address
indicated by MSR[IP]
Some types of instructions (for example load multiple/string and floating-point
instructions) cause additional interrupt recognition latency. Timing critical applications
must consider these instruction execution latencies in calculating worst-case interrupt
recognition latency.
Upon returning from a critical interrupt handler routine the core restarts any terminated or
uncompleted instructions, including terminated load multiple or load string instructions.
Note that these restarted load instructions may cause side-effects on peripheral devices that
have auto-decrementer or status bit changes caused by the subsequent load accesses.
The register settings for the critical interrupt are shown in Table 5-15.
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