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Gregory Nutt 2016-11-15 07:35:30 -06:00
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configs/sabre-6quad/README.txt
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@ -498,6 +498,15 @@ Open Issues:
CPU (which may not be CPU0). Perhaps that should be a spinlock to prohibit
execution of interrupts on CPU0 when other CPUs are in a critical section?
2016-11-15: When the critical section is used to lock a resource that is also
used by interupt handling, I believe that what is required is that the interrupt
handling logic must also take the spinlock. This will cause the interrupt handlers
on other CPUs to spin until leave_critical_section() is called.
NOTE: Currently enter_critical section takes the spinlock before disabling
(local) interrupts. That orderwould have to change or you could potentially get
deadlocks if the interrupt handler on the same CPU tries to take the spinlock.
2. Cache Concurency. This is a complex problem. There is logic in place now to
clean CPU0 D-cache before starting a new CPU and for invalidating the D-Cache
when the new CPU is started. REVISIT: Seems that this should not be necessary.