Nios® V Processor Software Developer Handbook

ID 743810
Date 10/06/2025
Public
Document Table of Contents

11.3.2.2.1. ECC Exception Occurs

When an ECC exception occurs, and the processor control transfers to the ECC handling code, it does the following:
  • Saves t0 register value into Machine Scratch (mscratch) register.
  • Determines if it is an ECC Exception from Machine Cause (mcause) register.
    • If not, passes control to the trap handler after restoring t0.
  • Determine if it is a correctable single-bit error from Machine Second Trap Value register (mtval2).
    • If yes, writeback the corrected data into the source memory.
    • If not, passes control to the ECC exception handler.