Nios® II Processor Reference Guide

ID 683836
Date 10/22/2020
Public
Document Table of Contents

3.4.2.14.7. The eccinj Register

The eccinj register injects 1 and 2 bit errors to the Nios® II processor’s internal RAM blocks that support ECC. Injecting errors allows the software to test the ECC error exception handling code. The error(s) are injected in the data bits, not the parity bits. The eccinj register is only available when ECC is present.

Table 35.  eccinj Control Register Fields
Bit Fields
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Reserved DC WB DTCM 3 DTCM 2
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
DTCM 1 DTCM 0 TLB DC DAT DC TAG ICDAT ICTAG RF

Software writes 0x1 to inject a 1 bit ECC error or 0x2 to inject a 2-bit ECC error to the RAM field. Hardware sets the value of the inject field to 0x0 after the error injection has occurred.

Table 36.  eccinj Control Register Field Descriptions
Field Description Access Reset Available
RF Inject an ECC error in the register file’s RAM. Read/Write 0 Only with ECC
ICTAG Inject an ECC error in the instruction cache Tag RAM. Read/Write 0 Only with ECC
ICDAT Inject an ECC error in the instruction cache data RAM. Read/Write 0 Only with ECC
DCTAG Inject ECC error in data cache tag RAM. Read/Write 0  
DCDAT Inject an ECC error in the data cache data RAM. Injection occurs on next store instruction that writes the data cache or the next line fill. Read/Write 0  
TLB Inject an ECC error in the MMU TLB RAM. Errors are injected in the tag portion of the VPN field. Read/Write 0 Only with ECC
DTCM0 Inject ECC error in DTCM0. Injection occurs on next store instruction that writes this DTCM. Read/Write 0  
DTCM1 Inject ECC error in DTCM1. Injection occurs on next store instruction that writes this DTCM. Read/Write 0  
DTCM2 Inject ECC error in DTCM2. Injection occurs on next store instruction that writes this DTCM. Read/Write 0  
DTCM3 Inject ECC error in DTCM3. Injection occurs on next store instruction that writes this DTCM. Read/Write 0  
DC WB Inject ECC error in data cache victim line buffer RAM. Injection occurs on the first word written into the victim buffer RAM when a dirty line is being written back. Read/Write 0  

Refer to “Working with ECC” for more information about when errors are injected.

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