March 2002 Release
855
Virtex-II Pro™ Platform FPGA Documentation
1-800-255-7778
Timer Resources
R
•
Differences in exception-related bits in the machine-state register (MSR). See
for a summary.
•
A new interrupt-return instruction (
rfci
) that supports critical interrupts. The
PowerPC 40x family uses the
rfi
instruction to return from noncritical interrupts,
which is used to return from all interrupts in the PowerPC 6xx/7xx family.
•
New special-purpose registers for recording exception information. The PowerPC 40x
family defines two registers:
-
The exception-syndrome register (ESR) used to identify the cause of an exception.
-
The data exception-address register (DEAR) used to record the memory-operand
effective address of a data-access instruction that causes certain exceptions. The
data-address register (DAR) performs a similar function in PowerPC 6xx/7xx
processors.
•
Greater flexibility in relocating the interrupt-handler table. The exception-vector
prefix register (EVPR) supports relocating the interrupt-handler table anywhere in
physical-address space, with a base address that falls on a 64KB-aligned boundary.
The PowerPC 6xx/7xx family supports two locations for the interrupt-handler table:
0x000
n_nnnn
or 0xFFF
n_nnnn
, selected by using the MSR[IP] bit.
•
New exceptions and interrupts are defined. Some exceptions and interrupts
supported by the PowerPC 6xx/7xx family are not supported by PowerPC 40x
processors.
summarizes the differences between the exception and interrupt
vectors defined by the two families. Gray-shaded cells represent unsupported
interrupt vectors. Not all processors within a family support all of the exceptions and
interrupts defined by the family.
Timer Resources
The PowerPC 40x family implements new timer features. These are:
•
The programmable-interval timer (PIT) register. This register decrements at the same
clock rate as the time base. Its function replaces that of the decrementer in the
PowerPC 6xx/7xx family.
Table E-6:
Summary of Exception and Interrupt Vector Differences
Vector Offset
PowerPC 40x Family
PowerPC 6xx/7xx Family
0x0100
Critical-Input
System Reset
0x0900
Decrementer
0x0D00
Trace
0x0F00
Performance Monitor
0x0F20
APU Unavailable
0x1000
Programmable-Interval Timer
Instruction-Translation Miss
0x1010
Fixed-Interval Timer
0x1020
Watchdog Timer
0x1100
Data-TLB Miss
Data-Translation Miss (loads)
0x1200
Instruction-TLB Miss
Data-Translation Miss (stores)
0x1300
Instruction-Address Breakpoint
0x1400
System Management
0x1700
Thermal Management
0x2000
Debug
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