1. Introduction[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 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 ├── COPYING.MIT ├── README └── recipes-example └── example └── example.bb 3 directories, 4 files
2.1. Update layer.conf file[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"
2.2. Create the machine for your demo[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/stm32mp1-mx.conf <path of OpenSTLinux distribution delivery>/layers/meta-st/meta-my-demo-layer/conf/machine/stm32mp1-demo.conf
- Open stm32mp1-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
- Replace STM32MP_MX_BASE by STM32MP_MY_DEMO_BASE
- Add these lines :
# Define specific common machine name
MACHINEOVERRIDES .= ":stm32mpmydemo"
- Uncomment variables to configure your own Boot Mode Choice, Boot Device Choice, Board Type Choice, DeviceTree files and path
2.3. Associate EULA with the new demo machine[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/.
Then replace the existing symbolic link with the machine used for your demo:
$ rm stm32mp1-mx $ ln -s ST_EULA_SLA stm32mp1-demo
2.4. Move DeviceTree files and project coming from STM32CubeMX tool[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 source]
Please update the README file with the information needed for building and executing the demo.
2.6. Clean up useless content[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 │ └── stm32mp1-demo -> ST_EULA_SLA │ └── ... │ └── layer.conf │ └── machine │ └── stm32mp1-demo.conf ├── COPYING.MIT ├── mx │ └── STM32MP157C-EV1 │ └── my-demo │ └── DeviceTree │ └── my-demo │ └── kernel │ └── stm32mp157c-my-demo.dts │ └── tf-a │ └── stm32mp157c-my-demo.dts │ └── stm32mp15-mx.h │ └── u-boot │ └── stm32mp157c-my-demo.dts │ └── stm32mp157c-my-demo-u-boot.dtsi │ └── stm32mp15-mx.h │ └── optee-os │ └── stm32mp157c-my-demo.dts └── README
3. Adding specific recipes and content necessary for your demo[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
...