STM32MPU Buildroot external tree

This repository is a Buildroot BR2_EXTERNAL tree dedicated to supporting the STMicroelectronics STM32MP1 and STM32MP2 platforms. Using this project is not strictly necessary as Buildroot itself has support for STM32MPU, but this BR2_EXTERNAL tree provide example configurations demonstrating how to use the different features of the STM32MPU platforms.

Available configurations

This BR2_EXTERNAL tree provides height example Buildroot configurations:

1. st_stm32mp157d_dk1_defconfig, which is a minimal configuration to support the STM32MP157D Discovery Kit 1 board. It builds the TF-A firmware, U-Boot bootloader, Linux kernel and a minimal user-space composed of just Busybox.

2. st_stm32mp157d_dk1_demo_defconfig, which is a more feature-ful configuration to support the STM32MP157D-DK1 Discovery Kit 1 board. It has support for OpenGL and Qt5 for graphics, for OP-TEE as a Trusted Execution Environment, for RAUC for OTA. It also shows how Device Tree files generated by CubeMX can be integrated in a Buildroot configuration.

3. st_stm32mp157f_dk2_defconfig, which is a minimal configuration to support the STM32MP157F-DK2 Discovery Kit 2 board. It builds the TF-A firmware, U-Boot bootloader, Linux kernel and a minimal user-space composed of just Busybox.

4. st_stm32mp157f_dk2_demo_defconfig, which is a more feature-ful configuration to support the STM32MP157F-DK2 Discovery Kit 2 board. It has support for OpenGL and Qt5 for graphics, for OP-TEE as a Trusted Execution Environment, for RAUC for OTA. It also shows how Device Tree files generated by CubeMX can be integrated in a Buildroot configuration.

5. st_stm32mp135f_dk_defconfig, which is a minimal configuration to support the STM32MP135F Discovery Kit board. It builds the TF-A firmware, U-Boot bootloader, Linux kernel and a minimal user-space composed of just Busybox.

6. st_stm32mp135f_dk_demo_defconfig, which is a more feature-ful configuration to support the STM32MP135F Discovery Kit board. It has support for OpenGL and Qt5 for graphics, for OP-TEE as a Trusted Execution Environment, for RAUC for OTA. It also shows how Device Tree files generated by CubeMX can be integrated in a Buildroot configuration.

7. st_stm32mp257f_ev1_defconfig, which is a minimal configuration to support the STM32MP257F Evaluation board board. It builds the TF-A firmware, U-Boot bootloader, Linux kernel and a minimal user-space composed of just Busybox.

8. st_stm32mp257f_ev1_demo_defconfig, which is a more feature-ful configuration to support the STM32MP135F Evaluation board board. It has support for Trusted-Firmware-m, for OpenGL and Qt5 for graphics, for OP-TEE as a Trusted Execution Environment, for RAUC for OTA. It also shows how Device Tree files generated by CubeMX can be integrated in a Buildroot configuration.

Feature	st_stm32mp157d_dk1	st_stm32mp157f_dk2	st_stm32mp157d_dk1_demo	st_stm32mp157f_dk2_demo	st_stm32mp135f_dk	st_stm32mp135f_dk_demo	st_stm32mp257f_ev1	st_stm32mp257f_ev1_demo
TF-A	v2.8-stm32mp-r2	v2.8-stm32mp-r2	v2.8-stm32mp-r2	v2.8-stm32mp-r2	v2.8-stm32mp-r2	v2.8-stm32mp-r2	v2.8-stm32mp-r2	v2.8-stm32mp-r2
U-Boot	v2022.10-stm32mp-r2	v2022.10-stm32mp-r2	v2022.10-stm32mp-r2	v2022.10-stm32mp-r2	v2022.10-stm32mp-r2	v2022.10-stm32mp-r2	v2022.10-stm32mp-r2	v2022.10-stm32mp-r2
Linux	v6.1-stm32mp-r2	v6.1-stm32mp-r2	v6.1-stm32mp-r2	v6.1-stm32mp-r2	v6.1-stm32mp-r2	v6.1-stm32mp-r2	v6.1-stm32mp-r2	v6.1-stm32mp-r2
OP-TEE	3.19.0-stm32mp-r2	3.19.0-stm32mp-r2	3.19.0-stm32mp-r2	3.19.0-stm32mp-r2	3.19.0-stm32mp-r2	3.19.0-stm32mp-r2	3.19.0-stm32mp-r2	3.19.0-stm32mp-r2
TF-M	N/A	N/A	N/A	N/A	N/A	N/A	No	v1.7.0-stm32mp25-r9.1-w2425
Qt5	No	No	Yes	Yes	No	Yes	No	Yes
OpenGL	No	No	Yes	Yes	No	Yes	No	Yes
WiFi	N/A	No	N/A	Yes	No	Yes	N/A	N/A
Bluetooth	N/A	No	N/A	Yes	No	Yes	N/A	N/A
Audio	No	No	Yes	Yes	N/A	N/A	N/A	N/A
Video	N/A	N/A	N/A	N/A	No	Yes	No	Yes
CubeMX v6.12.0 Device Tree	No	No	Yes	Yes	No	Yes	No	No
Cortex M Firmware examples	No	No	Yes Cortex M4	Yes Cortex M4	N/A	N/A	No	Yes Cortex M33
RAUC OTA	No	No	Yes	Yes	No	Yes	No	Yes

Note that upstream Buildroot also contains pre-defined configurations for STM32MPU platforms, but they use the upstream versions of TF-A, U-Boot and Linux, while the configurations in this BR2_EXTERNAL tree use the versions provided and supported by ST.

Starter package

If you want to use Buildroot on STM32MPU platforms without building everything yourself from source, we provide below a Starter Package. For each release and each Buildroot configuration, we provide:

• A README file that documents how the Starter Package has been built

• A pre-built image, ready to flash on an SD card, together with a Block map (which can be used with bmaptool to optimize the flashing process). This image contains a fully working system, with bootloaders, Linux kernel and root filesystem. Look at the flash and boot section to discover how to use the prebuilt images.

• A Software Development Kit (SDK) that contains a cross-compiler and set of libraries that allow you to build applications for the target. See the Buildroot advanced usage documentation to find out how to use the SDK.

• The complete list of open-source licenses and complete source code of all software components included in the pre-built image, for license compliance.

The following table provides the links to all these artifacts, compiled with the latest openstlinux-6.1-buildroot-2024.02.3-mpu-v24.06.26 release:

Configuration	README	Image	Block map	SDK	Licences	Sources
st_stm32mp157d_dk1	URL	URL	URL	URL	URL	URL
st_stm32mp157d_dk1_demo	URL	URL	URL	URL	URL	URL
st_stm32mp157f_dk2	URL	URL	URL	URL	URL	URL
st_stm32mp157f_dk2_demo	URL	URL	URL	URL	URL	URL
st_stm32mp135f_dk	URL	URL	URL	URL	URL	URL
st_stm32mp135f_dk_demo	URL	URL	URL	URL	URL	URL
st_stm32mp257f_ev1	URL	URL	URL	URL	URL	URL
st_stm32mp257f_ev1_demo	URL	URL	URL	URL	URL	URL

Building Buildroot from source

Pre-requisites

In order to use Buildroot, you need to have a Linux distribution installed on your workstation. Any reasonably recent Linux distribution (Ubuntu, Debian, Fedora, Redhat, OpenSuse, etc.) will work fine.

Then, you need to install a small set of packages, as described in the Buildroot manual System requirements section.

For Debian/Ubuntu distributions, the following command allows to install the necessary packages:

$ sudo apt install debianutils sed make binutils build-essential gcc g++ bash patch gzip bzip2 perl tar cpio unzip rsync file bc git

There are also optional dependencies if you want to use Buildroot features like interface configuration, legal information or documentation. Please see the corresponding manual section.

Getting the code

This BR2_EXTERNAL tree is designed to work with the 2024.02.x LTS version of Buildroot. However, we needed a few changes on top of upstream Buildroot, so you need to use our own Buildroot fork together with this BR2_EXTERNAL tree, and more precisely its st/2024.02.3 branch.

$ git clone -b st/2024.02.3 https://github.com/bootlin/buildroot.git

See our documentation on internal details for more information about the changes we have compared to upstream Buildroot.

Now, clone the matching branch of the BR2_EXTERNAL tree:

$ git clone -b st/2024.02.3 https://github.com/bootlin/buildroot-external-st.git

You now have side-by-side a buildroot directory and a buildroot-external-st directory.

Configure and build

Go to the Buildroot directory:

$ cd buildroot/

And then, configure the system you want to build by using one of the 8 defconfigs provided in this BR2_EXTERNAL tree. For example:

buildroot/ $ make BR2_EXTERNAL=../buildroot-external-st st_stm32mp157f_dk2_defconfig

We are passing two informations to make:

1. The path to BR2_EXTERNAL tree, which we have cloned side-by-side to the Buildroot repository

2. The name of the Buildroot configuration we want to build.

If you want to further customize the Buildroot configuration, you can now run make menuconfig, but for your first build, we recommend you to keep the configuration unchanged so that you can verify that everything is working for you.

Start the build:

buildroot/ $ make

This will automaticaly download and build the entire Linux system for your STM32MPU platform: cross-compilation toolchain, firmware, bootloader, Linux kernel, root filesystem. It might take between 30 and 60 minutes depending on the configuration you have chosen and how powerful your machine is.

Flashing and booting the system

The Buildroot configurations generate a compressed ready-to-use SD card image, available as output/images/sdcard.img.gz. You can also use the prebuilt images downloaded from the starter package section.

Flash this image on a SD card:

buildroot/ $ gzip -dc sdcard.img.gz | dd of=/dev/sdX bs=1M

You can also use the block map image file to accelerate the flashing process. The block map image is available as output/images/sdcard.img.bmap or can be downloaded from the starter package section. Both the block map file and the SD card image has to be in the same directory.

Note: bmaptool will not erase empty partition like the U-boot environment partition.

buildroot/ $ bmaptool copy sdcard.img.gz /dev/sdbX

(Note: this assumes your SD card appears as /dev/sdX on your system.)

Then:

1. Insert the microSD card

   • STM32MP157: connector CN15
   • STM32MP135: connector CN3
   • STM32MP257: connector CN1

2. Plug a micro-USB cable or USB-C for STM32MP257 and run your serial communication program on /dev/ttyACM0.

   • STM32MP157: connector CN11
   • STM32MP135: connector CN10
   • STM32MP257: connector CN21

3. Configure the SW1 switch to boot on SD card

   • STM32MP157: BOOT0 and BOOT2 to ON
   • STM32MP135: BOOT0 to ON, BOOT1 to OPEN, BOOT2 to ON
   • STM32MP257: BOOT0 to ON, BOOT1 and BOOT2 and BOOT3 to OPEN

4. Plug a USB-C cable or Barrel cable for STM32MP257 to power-up the board

   • STM32MP157: connector CN6
   • STM32MP135: connector CN12
   • STM32MP257: connector CN20

5. The system will start, with the console on UART. You can log-in as root with no password for the minimal configuration, or with root as the password for the demo configurations.

Note: it is also possible to flash the SD card while leaving it into the board, by using the STM32 Cube Programmer. See our Using the STM32 Cube Programmer page for more details.

Going further

• Using the STM32 Cube Programmer
• Using Device Tree files generated by STM32 CubeMX
• Using the Firmware examples for the Cortex M
• Testing display support
• Using WiFi
• Using Bluetooth
• Using Audio
• Using Camera
• Using Qt5 demos
• Using OP-TEE
• Using OTA with RAUC
• Internal details on this BR2_EXTERNAL tree
• Release notes

References

• Buildroot
• Buildroot reference manual
• Buildroot system development training course, with freely available training materials

Support

You can contact Bootlin at info@bootlin.com for commercial support on using Buildroot on STM32MP1 and STM32MP2 platforms.