1. Introduction[edit | edit source]
This article is intended for Yocto experts, or people who have some practical experience of the Yocto environmment.
This section describes the steps needed to create and configure a demo layer using DeviceTree files from the STM32CubeMX tool, and to add and configure a machine similar to those already supported by the OpenSTLinux Distribution Package (in particular the machine delivered inside the existing STM32MP BSP layer 'addons').
Reminder: this addon-layer is deployed under the following path in the delivery : <path of OpenSTLinux distribution delivery>/layers/meta-st/meta-st-stm32mp-addons/
2. Creating a new open embedded layer for your demo[edit | edit source]
You first need to create a new layer. See the latest How to create a new open embedded layer
After creation, you have under <path of OpenSTLinux distribution delivery>/layers/meta-st/:
$ tree meta-my-demo-layer meta-my-demo-layer ├── conf │ └── layer.conf ├── recipes-example │ └── example │ └── example.bb ├── COPYING.MIT └── README 3 directories, 4 files
2.1. Update layer.conf file[edit | edit source]
Open the layer.conf file and add the lines below for the licenses, demo layer path, and dependency with the STM32MP BSP layer 'addons' :
EULA_FILE_ST:stm32mpmydemo = "${LAYERDIR}/conf/eula/${MACHINE}" EULA_FILE_ST_MD5SUM:stm32mpmydemo = "8b505090fb679839cefbcc784afe8ce9" #Inform bitbake for adding another location to search for licenses LICENSE_PATH += "${LAYERDIR}/files/licenses" # Set a variable to get the STM32MP MX BSP location STM32MP_MY_DEMO_BASE = "${LAYERDIR}" # This should only be incremented on significant changes that may # cause compatibility issues with other layers LAYERVERSION_meta-my-demo-layer = "1" LAYERDEPENDS_meta-my-demo-layer = "stm-st-stm32mp-mx" # OpenEmbedded compatibility information # This should only be incremented on significant changes that will # cause compatibility issues with other layers LAYERVERSION_meta-my-demo-layer = "1" LAYERSERIES_COMPAT_meta-my-demo-layer = "scarthgap"
 Information
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| LAYERSERIES_COMPAT must be aligned with the version of OpenEmbedded used. Please refer to https://wiki.yoctoproject.org/wiki/Releases |
2.2. Create the machine for your demo[edit | edit source]
2.2.1. Prepare the machine configuration file[edit | edit source]
- Copy the machine delivered inside the existing STM32MP BSP layer 'addons' into your demo layer
cp <path of OpenSTLinux distribution delivery>/layers/meta-st/meta-st-stm32mp-addons/conf/machine/stm32mpXX-mx.conf <path of OpenSTLinux distribution delivery>/layers/meta-st/meta-my-demo-layer/conf/machine/stm32mp<X>-demo.conf
- Open stm32mp<X>-demo.conf and update the line below
#@NEEDED_BSPLAYERS: layers/meta-openembedded/meta-oe layers/meta-openembedded/meta-python layers/meta-st/meta-st-stm32mp-addons
- Add these lines after the series of includes:
# Define specific common machine name
MACHINEOVERRIDES .= ":stm32mpmydemo"
2.2.2. Configure the machine configuration file for your demo[edit | edit source]
In the customer machine file, move to User machine customization sections paragraph to configure your machine:
- Boot Scheme
- To select your boot scheme configuration(s), comment and uncomment the BOOTSCHEME_LABELS lines.
- Boot Device Choice
- To select your boot device configuration(s), comment and uncomment the BOOTDEVICE_LABELS lines.
- Support Feature Choice
- To select additional features to enable on board, uncomment the "MACHINE_FEATURES" proposed lines.
- Specific firmwares and kernel modules configuration
- This section allows user to configure some specificites related to its board hardware.
- - KERNEL_MODULE_AUTOLOAD you may need to feed this variable with the list of kernel modules that need to be loaded at boot time, such as 'goodix' for current touch-screen used on STM32MP157F-EV1 evaluation board.
- - BLUETOOTH_LIST in case you enable the bluetooth feature for your machine, you should set, at least, the firmware module to use for your hardware (e.g. 'linux-firmware-bluetooth-bcm4343' for STM32MP157F-DK2 discovery board).
- - WIFI_LIST in case you enable the wifi feature for your machine, you should set, at least, the firmware module to use for your hardware (e.g.'linux-firmware-bcm43430' for STM32MP157F-DK2 discovery board).
- CubeMX Project config
- You have to uncomment and configure the following variables to set your CubeMX project:
- - CUBEMX_DTB name of CubeMX generated device tree files, without file extension (e.g. stm32mp135f-<ProjectName>-mx)
- - CUBEMX_PROJECT path of CubeMX generated device tree files relative to layer path folder (e.g. mx/STM32MP135F-DK/my-demo/DeviceTree/my-demo)
- - CUBEMX_SOC_PACKAGE indicates (in upper case) which STM32MP package is used:
- - A: no crypt
- - C: crypt
- - D: no crypt, performance
- - F: crypt, performance
- This setting allows to set on Optee-os build the CFG_STM32_CRYP config switch to manage the presence of crypt hardware or not.
- - CUBEMX_BOARD_DDR_SIZE indicates the size of DDR available on BOARD in MB unit:
- - 512: 521MB size
- - 1024: 1GB size
- This setting allows to set on Optee-os build the CFG_DRAM_SIZE config switch.
- - CUBEMX_SOC_DVFS_OFF indicates if you like to disable the DVFS which are activated by default.
- - 0: Nothing specific done extra configuration switch defined
- - 1: Manage extra config switch for Optee-os build
In order to give a better view on how to configure these variables, some machine samples are provided to show how to set-up a disco and eval board CubeMX machine: refer to conf/machine/examples from meta-st-stm32mp-addons layer.
2.3. Associate EULA with the new demo machine[edit | edit source]
Copy the eula folder delivered inside the existing STM32MP BSP layer 'addons' into your demo layer
cp -Rf <path of OpenSTLinux distribution delivery>/layers/meta-st/meta-st-stm32mp-addons/conf/eula/ <path of OpenSTLinux distribution delivery>/layers/meta-st/meta-my-demo-layer/conf/.
Cleanup unexpected symbolic links from eula folder newly populated:
find <path of OpenSTLinux distribution delivery>/layers/meta-st/meta-my-demo-layer/conf/eula -type l -exec rm -f {} \;
Then create the symbolic link with the machine used for your demo:
cd <path of OpenSTLinux distribution delivery>/layers/meta-st/meta-my-demo-layer/conf/eula
ln -sf ST_EULA_SLA stm32mpX-demo
2.4. Move DeviceTree files and project coming from STM32CubeMX tool[edit | edit source]
The principle is that the user generates devicetree files for the targeted demo from the STM32CubeMX tool.
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These files are then moved into the “mx” folder created into your demo layer : <path of OpenSTLinux distribution delivery>/layers/meta-st/meta-my-demo-layer/mx/
Sub-folders are created and populated with the generated devicetree files:
mx/${CUBEMX_PROJECT}/kernel
mx/${CUBEMX_PROJECT}/u-boot
mx/${CUBEMX_PROJECT}/tf-a
mx/${CUBEMX_PROJECT}/optee-os
With CUBEMX_PROJECT that is equal to the value defined inside the machine used for the demo.
2.5. Update the README file[edit | edit source]
Please update the README file with the information needed for building and executing the demo.
2.6. Clean up useless content[edit | edit source]
You can delete the content of the recipes-example folder created by the create-layer command.
After making all of the updates, your demo layer should be similar to:
$ tree meta-my-demo-layer
meta-my-demo-layer
├── conf
│ ├── eula
│ │ ├── ST_EULA_SLA
│ │ ├── stm32mp''X''-demo -> ST_EULA_SLA
│ │ └── ...
│ ├── machine
│ │ └── stm32mp''X''-demo.conf
│ └── layer.conf
├── mx
│ └── ${CUBEMX_PROJECT}
│ ├── kernel
│ │ └── stm32mpXXXx-my-demo-mx.dts
│ ├── optee-os
│ │ └── stm32mpXXXx-my-demo-mx.dts
│ ├── tf-a
│ │ ├── stm32mpXX-mx.dtsi
│ │ ├── stm32mpXXXx-my-demo-mx.dts
│ │ └── stm32mpXXXx-my-demo-mx-fw-config.dts
│ └── u-boot
│ ├── stm32mpXXXx-my-demo-mx.dts
│ └── stm32mpXXXx-my-demo-mx-u-boot.dtsi
├── COPYING.MIT
└── README
3. Adding specific recipes and content necessary for your demo[edit | edit source]
Examples of further add-on components:
- Recipes for installing distro-specific configuration files
- Any image recipes specific to user distribution
- A psplash append file for a branded splash screen
- Any other append files to make custom changes
Some other added components (*bb) are more specific: images, system services, and so on (a non-exhaustive list is shown below):
- Recipes-core for psplash screen, systemd services
- Recipes-samples for example images
...