interrupt generation

:confused:

Device drivers typically access control registers associated with their

device. These registers are mapped into the Nios II address space. When

accessing device registers, the data cache must be bypassed to ensure that accesses are not lost or deferred due to the data cache.

For device drivers, the data cache should be bypassed by using the

ldio/stio family of instructions. On Nios II cores without a data cache,

these instructions behave just like their corresponding ld/st

instructions, and therefore are benign.

for c programmers, note that declaring a pointer as volatile does not

cause accesses using that volatile pointer to bypass the data cache. the

volatile keyword only prevents the compiler from optimizing out

accesses using the pointer.

This volatile behavior is different from the methodology for

the first-generation Nios processor.