Nios® II Processor Reference Guide

ID 683836
Date 8/28/2023
Document Table of Contents MPU Region Violation

MPU region violation exceptions are implemented only in Nios® II processors that include the MPU. An MPU region violation exception is generated under any of the following conditions:
  • An instruction fetch or data address matched a region but the permissions for that region did not allow the action to complete.
  • An instruction fetch or data address did not match any region.

The general exception handler reads the MPU region attributes to determine if the address did not match any region or which permissions were violated.

There are two kinds of MPU region violation exceptions:

  • MPU region violation (instruction)—Any instruction fetch can cause this exception.
  • MPU region violation (data)—Load, store, initda, and flushda instructions can cause this exception.

The general exception handler can inspect the exception.CAUSE field to determine which kind of MPU region violation exception occurred.