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I'm using a CortexA8 and I can't seem to enable interrupts...!
I'm using a "CPSIE I" instruction, I can see that the compiler (GCC) is not optimizing my code out... I have to manually stop the program with a debugger and update the I bit myself before I can see an interrupt fire..!?
Why? Any help would be much appreciated!
Cheers!
Is it because I am in user mode? I must make this a system call? SVC? etc? I can't do this operation in user mode can I?
Yes, it's because you are in User mode. User mode can't control the interrupt masks (CPSR.I/F), as this would allow it to prevent re-entry into the OS. (That doesn't mean that CPSR.I/F cannot be b1 in User mode, just that User mode cannot set them b1 itself).
So yes, you would need to move to a privileged mode to change the state of the interrupt masks. Typically that would be a system call, which would mean using a SVC.