IOT-GATE-iMX7 and SBC-IOT-iMX7: U-Boot: Building Images

Overview

The CompuLab device IOT-GATE-iMX7/SBC-IOT-iMX7 firmware consists of two components: Secondary Program Loader (SPL) and U-Boot. Both components are based on U-Boot source code.
SPL is the bootstrap utility invoked by the CPU internal boot ROM code of the i.MX7 SoC. U-Boot initializes hardware modules necessary for system boot and loads the operating system.
The latest U-Boot package is available at the CL-SOM-iMX7 Resources web page.

Building Firmware images for IOT-GATE-iMX7/SBC-IOT-iMX7

Getting U-Boot sources

There are two ways to get U-Boot sources that can be used as a baseline for the IOT-GATE-iMX7/SBC-IOT-iMX7 U-Boot. You can create a copy of "Das U-Boot" source tree or download a snapshot and extract it.
We assume that you have created /home/development/cl-som-imx7/u-boot directory for the IOT-GATE-iMX7/SBC-IOT-iMX7 B-Boot development.

Git clone

• Install git version control system.
• Create a clone of U-Boot tree

cd /home/development/cl-som-imx7/u-boot
git clone https://github.com/compulab/u-boot.git -b v2017.07-cl-som-imx7-1.9 u-boot-cl-som-imx7
cd u-boot-cl-som-imx7

• Create a branch for CL-SOM-iMX7 development

git checkout -b cl-som-imx7-1.9-devel

Building the firmware images

• First, compile U-Boot. The following commands create the u-boot.imx binary (along with other image types):

export ARCH=arm
export CROSS_COMPILE=arm-none-linux-eabi-
make mrproper
make cl-som-imx7_defconfig && make

• Merge the SPL and U-Boot images into one firmware image:

dd if=/dev/zero count=640 bs=1K | tr '\000' '\377' > cl-som-imx7-firmware
dd if=SPL of=cl-som-imx7-firmware bs=1K seek=1 conv=notrunc
dd if=u-boot.img of=cl-som-imx7-firmware bs=1K seek=64 conv=notrunc

• You can now install the cl-som-imx7-firmware file into an SD card or IOT-GATE-iMX7/SBC-IOT-iMX7 SPI flash.

See also

• Firmware Update
• Creating a bootable SD card
• U-Boot: Quick reference
• U-Boot images
• U-Boot documentation