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Configuration of Booting Nios® V and settings for each Boot Option

Configuration of Booting Nios® V and settings for each Boot Option

  • Updated

1. Introduction

This article introduces the Boot method used to automatically launch application programs for the Nios® V processor (hereafter as Nios® V).
Boot methods supported include Boot Copier, Execute in Place, and SDM Boot, It is possible to boot from all Quad SPI (QSPI) Flash memory by using the Generic Serial Flash interface (GSFI).

This article introduces the Boot Option available for Nios® V and its various settings.

 

2. Types of Boot Methods

The following Boot methods are available to boot Nios® V.

  • Boot Copier
    • Downloading the program from the boot source (QSPI Flash, etc.) to RAM and executing it.

  • Execute In Place (XIP)
    • Execute the program without downloading it from the boot source.

  • SDM Boot
    • A method of downloading the program to RAM and executing it using the SDM firmware functions.

Table 1 shows the characteristics of each Boot option.

Table 1. Characteristics of each Boot option

Boot method Characteristics
Boot Copier
  • Faster execution speed in case of cache miss-hit compared to XIP.
  • Flexibility by editing Boot Copier.
  • RAM space is required to deploy the application code.
XIP
  • Immediate startup is possible.
  • RAM space can be saved.
  • When compared with Boot Copier, execution speed is slower in case of cache miss-hit.

SDM Boot
  • Supported by devices containing SDM block such as Stratix® 10 and Agilex™.
  • Requires RAM for Bootloader and RAM for Application.
  • Since it needs to be extracted to RAM, the operation after extraction is the same as Boot Copier.

 

2-1. About Boot Copier

Boot Copier is a method of executing the application code in On-Chip RAM or External RAM.

Nios® V recommends using GSFI, which saves the Application code in Flash ROM and Boots Nios® V in the following flow when Nios® V is un-reset.

  1. Release the reset of Nios® V
  2. Nios® V executes Boot Copier on Flash ROM which is set as Reset Vector.
  3. Boot Copier copies the Application code to RAM
  4. Nios® V executes the Application code in RAM.

Figure 1. System configuration when Boot Copier is used

 

2-2. About XIP

XIP is a Boot method that assigns the Application code to the Flash Controller and runs Nios® V on Flash ROM.

__.png Note: Read/write data areas such as .rwdata, .heap, and .stack sections set in Linker srcipt must be placed in RAM even when used in the XIP configuration, because they involve Flash rewriting.

The Application code is saved in Boot Memory connected to GSFI, and Nios® V is executed in the following flow triggered by the reset release.

  1. Release the reset of Nios® V
  2. Nios® V executes the Application code on the Boot Memory set to Reset Vector.

Figure 2. System configuration diagram when XIP is used

 

2-3. About SDM Boot

SDM Boot is a method of booting Nios® V by storing the Application code in Boot Memory connected to SDM for devices equipped with SDM, such as Stratix® 10 FPGAs and Agilex™ FPGAs.

SDM stands for Secure Device Manager, a module designed to enhance security functions. For more details, please refer to the following.

____.pngReference: Agilex™ FPGA "Security" section

SDM boot is performed in the following flow

  1. Nios® V is unreset
  2. Nios® V executes SDM bootloader from On-Chip Memory
  3. SDM bootloader copies the Application code stored in the Boot ROM connected to SDM to On-Chip RAM or External RAM
  4. Nios® V executes the Application code in On-Chip RAM or External RAM.

Figure 3. System configuration diagram when SDM Boot is used

 

3. Introduction of each Boot Option

Depending on the combination of Boot method and Boot Memory, there are four different ways to Boot Nios® V.

Please refer to the link in Table 2 for each type of Boot Option.

Table 2. Types of Boot Option

Boot Option Boot Memory

Application
Code Boot Option Destination

(Boot Source)

 Application
Execution Time Location 		Boot Copier

User Guide Link

GSFI Boot
(Boot Copier)

QSPI Flash Memory
(AS Configuration)

QSPI Flash
Memory

RAM
(internal, external)

 GSFI bootloader

User Guide

GSFI Boot
(XIP)

QSPI Flash Memory
(AS Configuration)

QSPI Flash
Memory

QSPI Flash Memory

 alt_load() function

User Guide

SDM Boot

QSPI Flash Memory
（QSPI Flash Memory (AS Configuration)

QSPI Flash
Memory

RAM
(internal, external)

 SDM bootloader User Guide

On-Chip RAM Boot

On-Chip Memory
(OCRAM)

 On chip RAM On-chip RAM Boot Copier not required User Guide

TCM Boot

Tightly Coupled
 Memory
 （TCM）

 Instruction TCM

Instruction
TCM

 Boot Copier not required User Guide

On chip Flash Boot(Boot Copier) *For Max10

On chip Flash
(User Flash Memory)

 User Flash Memory

On chip RAM

 Boot Copier  -

On chip Flash Boot(XIP)
*For Max10

On chip Flash
(User Flash Memory)

 User Flash Memory

User Flash
Memory

 alt load() function -

 

Please refer to the following reference document for a summary of various settings.

　 ____.png Reference: Nios® V Embedded Processor Design Handbook 4.3. Nios® V Processor Booting Methods

 

Conclusion

This article introduced the Boot Option available for Nios® V and its various settings.

We hope this article will help you to understand the features of various Boot Options, and to consider the method that best suits your specifications.

For more information on Nios® V processors, please refer to the manufacturer's page below.

 

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