Interrupts and Exceptions
e200z3 Power Architecture Core Reference Manual, Rev. 2
4-28
Freescale Semiconductor
4.7
Exception Recognition and Priorities
The following list of exception categories describes how the e200z3 handles exceptions up to the point of
signaling the appropriate interrupt to occur. Also, instruction completion is defined as updating all
architectural registers associated with that instruction as necessary, and then removing the instruction from
the pipeline.
•
Interrupts caused by asynchronous events (exceptions). These exceptions are further distinguished
by whether they are maskable and recoverable.
— Asynchronous, non-maskable, non-recoverable: System reset by assertion of p_reset_b.
Has highest priority and is taken immediately regardless of other pending exceptions or
recoverability. (Includes watchdog timer reset control and debug reset control)
— Asynchronous, non-maskable, possibly non-recoverable: Non-maskable interrupt by assertion
of p_nmi_b
Has priority over any other pending exception except system reset conditions. Recoverability
is dependent on whether CSRR0/1 are holding essential state info and are overwritten when the
NMI occurs.
— Asynchronous, maskable, non-recoverable: Machine check interrupt.
Has priority over any other pending exception except system reset conditions; is dependent on
the source of the exception. Typically non-recoverable.
— Asynchronous, maskable, recoverable: External input, fixed-interval timer, decrementer,
critical input, unconditional debug, external debug event, debug counter event, and watchdog
timer interrupts.
Before handling this type of exception, the processor needs to reach a recoverable state. A
maskable recoverable exception remains pending until taken or cancelled by software.
•
Synchronous, non-instruction-based interrupts. The only exception in this category is the interrupt
taken debug exception, recognized by an interrupt taken event. It is not considered
instruction-based but is synchronous with respect to program flow.
Table 4-31. SPE Floating-Point Round Interrupt Register Settings
Register
Setting Description
SRR0
Set to the effective address of the instruction following the excepting SPE instruction.
SRR1
Set to the contents of the MSR at the time of the interrupt
MSR
UCLE 0
SPE 0
WE
0
CE
—
EE
0
PR
0
FP
0
ME
—
FE0
0
DE
—
FE1
0
IS
0
DS
0
RI
—
ESR
SPE, [VLEMI]. All other bits cleared.
MCSR
Unchanged
DEAR
Unchanged
Vector
IVPR[32–47] || IVOR34[48–59] || 0b0000
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