Creating-a-Bootscript.md

^{Back | Contents
Appendix}

Creating a Bootscript

• Summary
• Pre-requisites
• Steps
  • Create the bootscript source file
  • Compile the boot script source
  • Copy the compiled script to de10-nano
• References

Summary

If you need to run some additional commands at boot time, instead of updating bootcmd in u-boot sources and writing to sd card, it's easier to just create a script file and copy that to the fat partition. Here we will create a simple bootscript that enables the required registers for access to SDRAM.

Pre-requisites

You will require U-Boot sources available as described in the Building U-Boot section. This section shows how to modify bootcmd to check for a bootscript and you will need to have followed the same/similar steps when setting up U-Boot for your device.

Steps

Create the bootscript source file

We'll first write all the commands we need in a text file called bootscript.txt. This file will be compiled into a bootscript image file.

For my specific example, I need to perform the following steps:

1. Check if an image titled sdr.rbf is present in the fat partition.
2. If yes, then modify registers before flashing the design and then modify a few registers after than and then continue.

The code I'm using here is specific to accessing SDRAM from the FPGA, you can replace it with whatever you need:

if test -e mmc 0:1 sdr.rbf; then
  echo "Found sdr.rbf"
  mw 0xFFC25080 0x0
  fatload mmc 0:1 0x3000000 sdr.rbf
  fpga load 0 0x3000000 0x700000
  mw 0xFFC2505C 0xA
  mw 0xFFC25080 0xFFFF
else
  echo sdr.rbf not found, doing nothing
fi;

Save this as bootscript.txt.

Compile the boot script source

We need to compile the bootscript source so that U-Boot can read it. U-Boot ships with a compiler called mkimage which we'll use to compile for the de10-nano as follows:

$DEWD/u-boot/tools/mkimage -C none -A arm -T script -d bootscript.txt u-boot.scr

The params used here are explained as follows:

• -C none - No compression
• -A arm - ARM architecture
• -T script - this is a script type
• -d booscript.txt - path to the source file
• u-boot.scr - Output file name

Copy the compiled script to de10-nano

Copy the u-boot.scr to the fat partition of the de10-nano. This can be done with the following commands:

scp u-boot.scr root@<de10-ip-address>:~

# Login to de10-nano and copy the file to fat.
ssh root@<de10-ip-address>
mkdir -p fat
mount /dev/mmcblk0p1 fat
cp u-boot.scr fat/
umount fat

And that's it!

References

Sunxi U-Boot - The command, syntax and params for mkimage are from this page.

Next | Back to table of contents

Back | SSH Without Password

^{Appendix | Table of Contents}