Nios® V Processor Reference Manual

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ID 683632
Date 1/27/2025
Public
Document Table of Contents
Document Table of Contents x
1. Overview 2. Nios® V/c Processor 3. Nios® V/m Processor 4. Nios® V/g Processor 5. Nios V Processor Reference Manual Archives 6. Document Revision History for the Nios® V Processor Reference Manual
1. Overview x
1.1. Quartus® Prime Software Support
2. Nios® V/c Processor x
2.1. Processor Performance Benchmarks 2.2. Processor Pipeline 2.3. Processor Architecture 2.4. Programming Model 2.5. Core Implementation
2.3. Processor Architecture x
2.3.1. General-Purpose Register File 2.3.2. Arithmetic Logic Unit 2.3.3. Reset and Debug Signals 2.3.4. Instruction Cycles 2.3.5. Memory and I/O Organization 2.3.6. Error Correction Code (ECC)
2.3.5. Memory and I/O Organization x
2.3.5.1. Instruction and Data Buses 2.3.5.2. Address Map
2.3.5.1. Instruction and Data Buses x
2.3.5.1.1. Instruction Manager Port 2.3.5.1.2. Data Manager Port 2.3.5.1.3. Choosing a Suitable Interface
2.4. Programming Model x
2.4.1. Privilege Levels
2.5. Core Implementation x
2.5.1. Instruction Set Reference
3. Nios® V/m Processor x
3.1. Processor Performance Benchmarks 3.2. Processor Pipeline 3.3. Processor Architecture 3.4. Programming Model 3.5. Core Implementation
3.1. Processor Performance Benchmarks x
3.1.1. Pipelined 3.1.2. Non-pipelined
3.2. Processor Pipeline x
3.2.1. Pipelined Architecture 3.2.2. Non-pipelined Architecture
3.3. Processor Architecture x
3.3.1. General-Purpose Register File 3.3.2. Arithmetic Logic Unit 3.3.3. Reset and Debug Signals 3.3.4. Control and Status Registers 3.3.5. Instruction Cycles 3.3.6. Trap Controller (CLINT) 3.3.7. Memory and I/O Organization 3.3.8. RISC-V based Debug Module 3.3.9. Error Correction Code (ECC)
3.3.6. Trap Controller (CLINT) x
3.3.6.1. Related Control and Status Register 3.3.6.2. Direct Mode 3.3.6.3. Vectored Mode
3.3.6.1. Related Control and Status Register x
3.3.6.1.1. Machine Status Register (mstatus) 3.3.6.1.2. Machine Trap-Vector Base-Address Register (mtvec) 3.3.6.1.3. Machine Interrupt Register (mip and mie) 3.3.6.1.4. Machine Exception Program Counter Register (mepc) 3.3.6.1.5. Machine Cause Register (mcause) 3.3.6.1.6. Machine Trap Value Register (mtval)
3.3.6.2. Direct Mode x
3.3.6.2.1. Hardware Implementation 3.3.6.2.2. Software Implementation
3.3.6.3. Vectored Mode x
3.3.6.3.1. Hardware Implementation 3.3.6.3.2. Software Implementation
3.3.7. Memory and I/O Organization x
3.3.7.1. Instruction and Data Buses 3.3.7.2. Address Map
3.3.7.1. Instruction and Data Buses x
3.3.7.1.1. Instruction Manager Port 3.3.7.1.2. Data Manager Port 3.3.7.1.3. Choosing a Suitable Interface
3.3.8. RISC-V based Debug Module x
3.3.8.1. Debug Module 3.3.8.2. Abstract Commands 3.3.8.3. Program Buffer 3.3.8.4. Debug Mode 3.3.8.5. Hardware Trigger Module 3.3.8.6. JTAG Debug Transport Module 3.3.8.7. Nios® V Processor Implementation
3.3.8.1. Debug Module x
3.3.8.1.1. Reset/Halt/Run Control 3.3.8.1.2. Hart States 3.3.8.1.3. Debug Module Register
3.3.8.2. Abstract Commands x
3.3.8.2.1. Access Register Command 3.3.8.2.2. Using Access Register Command
3.3.8.3. Program Buffer x
3.3.8.3.1. Using Program Buffer
3.3.8.4. Debug Mode x
3.3.8.4.1. Enter Debug Mode 3.3.8.4.2. Exit Debug Mode 3.3.8.4.3. Core Debug Registers
3.3.8.5. Hardware Trigger Module x
3.3.8.5.1. Trigger Registers 3.3.8.5.2. Type of Address/Data Match Triggers 3.3.8.5.3. Using Triggers
3.3.8.6. JTAG Debug Transport Module x
3.3.8.6.1. JTAG DTM Registers 3.3.8.6.2. Accessing Debug Module Interface
3.4. Programming Model x
3.4.1. Privilege Levels 3.4.2. Control and Status Registers (CSR) Mapping
3.4.1. Privilege Levels x
3.4.1.1. Machine Mode (M-mode) 3.4.1.2. Debug Mode (D-mode)
3.4.2. Control and Status Registers (CSR) Mapping x
3.4.2.1. Control and Status Register Field 3.4.2.2. Memory Mapped Registers Fields
3.5. Core Implementation x
3.5.1. Instruction Set Reference
4. Nios® V/g Processor x
4.1. Processor Performance Benchmarks 4.2. Processor Pipeline 4.3. Processor Architecture 4.4. Programming Model 4.5. Core Implementation
4.3. Processor Architecture x
4.3.1. General-Purpose Register File 4.3.2. Arithmetic Logic Unit 4.3.3. Multipy and Divide Units 4.3.4. Floating-Point Unit 4.3.5. Custom Instruction 4.3.6. Instruction Cycles 4.3.7. Reset and Debug Signals 4.3.8. Control and Status Registers 4.3.9. Trap Controller (CLINT) 4.3.10. Memory and I/O Organization 4.3.11. RISC-V based Debug Module 4.3.12. Error Correction Code (ECC) 4.3.13. Branch Prediction 4.3.14. Lockstep Module
4.3.4. Floating-Point Unit x
4.3.4.1. IEEE 754 Exception Conditions 4.3.4.2. Floating Point Operations
4.3.4.2. Floating Point Operations x
4.3.4.2.1. Floating Point Classification
4.3.9. Trap Controller (CLINT) x
4.3.9.1. Related Control and Status Register 4.3.9.2. Direct Mode 4.3.9.3. Vectored Mode
4.3.9.1. Related Control and Status Register x
4.3.9.1.1. Machine Status Register (mstatus) 4.3.9.1.2. Machine Trap-Vector Base-Address Register (mtvec) 4.3.9.1.3. Machine Interrupt Register (mip and mie) 4.3.9.1.4. Machine Exception Program Counter Register (mepc) 4.3.9.1.5. Machine Cause Register (mcause) 4.3.9.1.6. Machine Trap Value Register (mtval) 4.3.9.1.7. Machine Second Trap Value Register (mtval2)
4.3.9.2. Direct Mode x
4.3.9.2.1. Hardware Implementation 4.3.9.2.2. Software Implementation
4.3.9.3. Vectored Mode x
4.3.9.3.1. Hardware Implementation 4.3.9.3.2. Software Implementation
4.3.10. Memory and I/O Organization x
4.3.10.1. Instruction and Data Buses 4.3.10.2. Address Map 4.3.10.3. Cache Memory 4.3.10.4. Tightly Coupled Memory
4.3.10.1. Instruction and Data Buses x
4.3.10.1.1. Instruction Manager Port 4.3.10.1.2. Data Manager Port
4.3.10.3. Cache Memory x
4.3.10.3.1. Instruction Cache 4.3.10.3.2. Data Cache 4.3.10.3.3. Configurable Cache Memory 4.3.10.3.4. Bypassing Cache (Peripheral Region) 4.3.10.3.5. Using Cache Memory Effectively
4.3.10.4. Tightly Coupled Memory x
4.3.10.4.1. Instruction and Data Tightly Coupled Memory 4.3.10.4.2. Accessing Tightly Coupled Memory 4.3.10.4.3. Using Tightly Coupled Memory Effectively
4.3.11. RISC-V based Debug Module x
4.3.11.1. Debug Module 4.3.11.2. Abstract Commands 4.3.11.3. Program Buffer 4.3.11.4. Debug Mode 4.3.11.5. Hardware Trigger Module 4.3.11.6. JTAG Debug Transport Module 4.3.11.7. Nios® V Processor Implementation
4.3.11.1. Debug Module x
4.3.11.1.1. Reset/Halt/Run Control 4.3.11.1.2. Hart States 4.3.11.1.3. Debug Module Register
4.3.11.2. Abstract Commands x
4.3.11.2.1. Access Register Command 4.3.11.2.2. Using Access Register Command
4.3.11.3. Program Buffer x
4.3.11.3.1. Using Program Buffer
4.3.11.4. Debug Mode x
4.3.11.4.1. Enter Debug Mode 4.3.11.4.2. Exit Debug Mode 4.3.11.4.3. Core Debug Registers
4.3.11.5. Hardware Trigger Module x
4.3.11.5.1. Trigger Registers 4.3.11.5.2. Type of Address/Data Match Triggers 4.3.11.5.3. Using Triggers
4.3.11.6. JTAG Debug Transport Module x
4.3.11.6.1. JTAG DTM Registers 4.3.11.6.2. Accessing Debug Module Interface
4.3.12. Error Correction Code (ECC) x
4.3.12.1. ECC Interface 4.3.12.2. ECC Error Injection 4.3.12.3. Affected CSR during ECC Event
4.4. Programming Model x
4.4.1. Privilege Levels 4.4.2. Control and Status Registers (CSR) Mapping (CLINT)
4.4.1. Privilege Levels x
4.4.1.1. Machine Mode (M-mode) 4.4.1.2. Debug Mode (D-mode)
4.4.2. Control and Status Registers (CSR) Mapping (CLINT) x
4.4.2.1. Control and Status Register Field (CLINT) 4.4.2.2. Memory Mapped Registers Fields
4.5. Core Implementation x
4.5.1. Instruction Set Reference
1. Overview
2. Nios® V/c Processor
3. Nios® V/m Processor
4. Nios® V/g Processor
5. Nios V Processor Reference Manual Archives
6. Document Revision History for the Nios® V Processor Reference Manual

3.3.8.1. Debug Module

The Debug Module supports the following operations:
  1. Provide information about the processor’s implementation to the debugger.
  2. Allow users to halt and resume the processor.
  3. Provide halt status on the processor.
  4. Provide abstract read and write access to the halted processor’s GPRs through abstract command.
  5. Provide ndm_reset_in and dbg_reset_out signals that allow debugging from the reset vector after reset.
  6. Provide abstract access to non-GPR hart registers through abstract command.
  7. Provide a Program Buffer to force the hart to execute arbitrary instructions through abstract commands.
The Nios® V processor supports only one hart. Therefore:
  • You cannot apply hart selection.
  • The bit fields that differentiate between "all harts" and "any harts" are treated as the same.
  • It simplifies related bit fields( such as dmstatus.allhavereset and dmstatus.anyhavereset to dmstatus.*havereset throughout the document.

Section Content
Reset/Halt/Run Control
Hart States
Debug Module Register

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