Re: Privilege Levels Below User

Lawrence D'Oliveiro wrote:
 

In particular, the DEC definition of a “fault” is that the saved PC on
the stack still points at the instruction that caused the exception, so
a return-from-exception will attempt to re-execute the same
instruction. This is exactly what you want for page faults, for
example, but also for long-running interruptible instructions that
haven’t finished yet.

 

Whereas a “trap” left the PC pointing at the following instruction. So
a return from the exception handler will simply resume execution there.

 
Both have the property where the PC is pointing at the first instruction
not executed.