Building U-Boot for MitySOM-AM57X¶
- Table of contents
- Building U-Boot for MitySOM-AM57X
Before you begin¶
There are multiple ways to customize and compile the U-Boot for your project. Please try to build U-Boot as-is with no changes before you try to add your customizations. This will ensure your environment and toolchain are setup correctly.
- Docker Build - Build using a Docker image (as described in Docker Build Environment
- ARM toolchain - You can use a previously compiled ARM toolchain provided by ARM.
- Yocto Environment - If you are using the docker environment and Yocto for your filesystem, you can use its tools to customize and build U-Boot.
In most cases, you will use one of the first two options for initial bring-up and testing. Then, once you have everything working you can integrate your custom code into Yocto.
Critical Link U-Boot Repository¶
Critical Link recommends using the mitysom-u-boot-2023.04 branch on our git server: https://support.criticallink.com/gitweb/?p=u-boot-ti.git;a=summary
Other MitySOM-AM57x U-Boot branches seen on the repository should not be considered stable, and are used for internal feature development.
U-Boot Build - Docker¶
See Docker Build Environment for details on how to setup and install the Docker build environment. Once that is installed, you can build U-Boot using the following commands:
git clone --branch mitysom-u-boot-2023.04 https://support.criticallink.com/git/u-boot-ti.git cd u-boot-ti docker run --rm --volume "$PWD:/work" --workdir=/work mitysom_ubuntu:22.04 ./57x-build.sh
If the build is successful, you will see MLO and u-boot.img files in the current directory. You can copy those to your boot media to test your new build. When U-Boot boots, it will display the build date and time. Please check this to make sure your new U-Boot files are being used.
For example, note the two dates, one for the MLO and one for the u-boot.img:
U-Boot SPL 2023.04-00489-g5da3ed2aefa (Jul 30 2025 - 11:46:33 -0400) DRA762-GP ES1.0 ABZ package no pinctrl state for default mode Firmware loading failed for ipu2 Trying to boot from MMC1 Loading Environment from FAT... *** Error - No Valid Environment Area found *** Warning - bad env area, using default environment Loading Environment from MMC... MMC Device 1 not found *** Warning - No MMC card found, using default environment U-Boot 2023.04-00489-g5da3ed2aefa (Jul 30 2025 - 11:46:33 -0400)
An example pinmux for Critical Link's development board can be found in board/cl/mitysom-57x/mux_data.h.
Please contact Critical Link at info@criticallink.com if you need help with customizing your defconfig and pinmux for your application.
Deploy Scripts/Helpful Scripts¶
Several additional scripts are provided to do helpful things.
57x-copy.sh - Copies the files to a locally mounted SD card (assumed to be at /media/$USER).57x-push.sh - Push the files to a SD card connected to a board over the network. You must supply a SSH connection string as the first argument (ex: root@<board ip address> ) or configure a ssh host target.
U-Boot Build - Yocto¶
For this option, you should have an environment setup as described in Docker build environment and Building the filesystem for the MitySOM-AM57x.
With this option, the general Yocto setup configures your build environment. You can compile U-Boot by running bitbake commands from your build directory.
Customize your U-Boot¶
You can customize U-Boot by pointing the U-Boot recipe to your new branch location.
In your Yocto meta layer, create a u-boot bbappend file. File name is important to match existing u-boot recipe name, as of Feb 2021 the name is below
[meta-mitysom.git] / recipes-bsp / u-boot / attachment:u-boot-cl-ti_2023.04.bb
mkdir recipes-bsp/u-boot/ vim u-boot-ti-staging_2023.03.bbappend
UBOOT_GIT_URI_mitysom-am57x = "git://support.criticallink.com/git/u-boot-ti.git"
UBOOT_GIT_PROTOCOL_mitysom-am57x = "http"
BRANCH = "mitysom-u-boot-2023.04"
SRCREV = "${AUTOREV}"
- Point UBOOT_GIT_URI* to your repository
- Update BRANCH to match your branch
- SRCREV can be set to a specific git hash if you want to lock to a specific commit instead of letting it grab the latest in the branch.
Building U-Boot¶
Then, to build U-Boot (note that this is within the previously configured Docker environment):
oe-layersetup$ ./docker-poky.sh pokyuser@cc6ebed1f954:/work$ ./57x-setup.sh --next pokyuser@cc6ebed1f954:/work$ export MACHINE=mitysom-am57x pokyuser@cc6ebed1f954:/work$ pushd build pokyuser@cc6ebed1f954:/work$ source conf/setenv user@8ec23474095b:~$ MACHINE=mitysom-am57x bitbake virtual/bootloader
If the build is successful, you will find your MLO and u-boot.img file in build/deploy-ti/images/mitysom-am57x/.
Verifying Your U-Boot Output and Build¶
If successful, you should see the following in the build output:
MKIMAGE u-boot.img MKIMAGE MLO make[1]: Leaving directory '/export/home/jsava/u-boot-ti/build-mitysom57x'
When U-Boot boots, it will display the build date and time. Please check this to make sure your new U-Boot files are being used.
U-Boot SPL 2023.04-g5766bfa7bf (Aug 07 2025 - 19:34:19 +0000) DRA762-GP ES1.0 ABZ package no pinctrl state for default mode Firmware loading failed for ipu2 Trying to boot from MMC1 Loading Environment from FAT... OK U-Boot 2023.04-g5766bfa7bf (Aug 07 2025 - 19:34:19 +0000) CPU : DRA762-GP ES1.0 ABZ package Model: Critical Link MitySOM-AM57x Board: MitySOM-57x FPGA DRAM: 2 GiB Core: 74 devices, 28 uclasses, devicetree: separate MMC: OMAP SD/MMC: 0 Loading Environment from FAT... OK MitySOM-57x - Model No: 5728-PJ-4AA-RC Serial No: 20015828 Part Number: 80-001294RC-1B Warning: fastboot.board_rev: unknown board revision invalid mmc device board_set_pru_ethaddr Net: eth4: ethernet@48484000
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