Embedded Systems Design, 2nd Edition

198 Embedded systems design

RISC exceptions

RISC architectures have a slightly different approach to

exception handling compared to that of CISC architectures. This

difference can catch designers out.

Taking the PowerPC architecture as an example, there are

many similarities: an exception is still defined as a transition from

the user state to the supervisor state in response to either an

external request or error, or some internal condition that requires

servicing. Generating an exception is the only way to move from

the user state to the supervisor state. Example exceptions include

external interrupts, page faults, memory protection violations and

bus ...