Nios® V Processor Reference Manual

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ID 683632
Date 11/15/2021
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Document Table of Contents
Document Table of Contents x
1. About this Document 2. Nios® V/m Processor 3. Document Revision History for the Nios® V Processor Reference Manual
1. About this Document x
1.1. Overview
2. Nios® V/m 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. Control and Status Registers 2.3.4. Exception Controller 2.3.5. Interrupt Controller 2.3.6. Memory and I/O Organization 2.3.7. RISC-V based Debug Module
2.3.5. Interrupt Controller x
2.3.5.1. Timer and Software Interrupt Module
2.3.6. Memory and I/O Organization x
2.3.6.1. Instruction and Data Buses
2.3.6.1. Instruction and Data Buses x
2.3.6.1.1. Instruction Manager Port 2.3.6.1.2. Data Manager Port 2.3.6.1.3. Address Map
2.3.7. RISC-V based Debug Module x
2.3.7.1. Debug Mode 2.3.7.2. Halt from Debug Module 2.3.7.3. Debug Implementation 2.3.7.4. Abstract Commands in Debug Mode 2.3.7.5. Hardware/Software Interface
2.4. Programming Model x
2.4.1. Privilege Levels 2.4.2. Control and Status Registers (CSR) Mapping
2.4.1. Privilege Levels x
2.4.1.1. Machine Mode (M-mode) 2.4.1.2. Debug Mode (D-mode)
2.4.2. Control and Status Registers (CSR) Mapping x
2.4.2.1. Control and Status Register Field
2.5. Core Implementation x
2.5.1. Instruction Set Reference
1. About this Document
2. Nios® V/m Processor
3. Document Revision History for the Nios® V Processor Reference Manual

2.3.7.5. Hardware/Software Interface

Debug Module read or write to Debug Module registers, which initiate the interaction with the debugger. Each register has a fixed address as specified in the RISC-V Debug Support specification. Debugger can determine the register implementation status by write or read from the Debug Module registers. Unimplemented registers return 0 when read.

Debugger can check the status of the system by reading Debug Module Status (dmstatus) register. Debug Module Status register is read-only and provides status of the Debug Module and the selected harts.

You can access a specific hart by writing to the hartsel field in dmcontrol. Other fields in dmcontrol specify the action a debugger can take.

Halt Summary 0 (haltsum0) register reflects the status of a hart (halted/not halted). The LSB of this register can reflect whether hart is halted or not. Other bits is always 0. This is a read-only register of the debugger.

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