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processor when the priority of the interrupt is greater than the priority
contained in the task register for that processor, and when the priority of
the interrupt is greater than any interrupt which is in-service for that
processor. An interrupt is considered to be in service from the time its
vector is returned during an interrupt acknowledge cycle until an EOI is
received for that interrupt. The EOI cycle indicates the end of processing
for the highest priority in-service interrupt.
In the distributed delivery mode, the interrupt is pointed to one or more
processors but it will be delivered to only one processor. Therefore, for
externally sourced or I/O interrupts, multicast delivery is not supported.
The interrupt is delivered to a processor when the priority of the interrupt
is greater than the priority contained in the task register for that processor,
and when the priority of the interrupt is greater than any interrupt which is
in-service for that processor, and when the priority of that interrupt is the
highest of all interrupts pending for that processor, and when that interrupt
is not in-service for the other processor. If both destination bits are set for
each processor, the interrupt will be delivered to the processor that has a
lower task register priority.
Note
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Because a deadlock condition can occur when the task register
priorities for each processor are the same and both processors are
targeted for interrupt delivery, the interrupt will be delivered to
processor 0.
Raven Interrupt Controller Implementation
2
2-63
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