DESK-MX6UL-L/Development/Building the Yocto BSP

History
Issue Date	Notes
2021/07/21	First DESK-MX6UL-L release
2022/03/16	DESK-MX6UL-L 3.0.0 release
2023/05/05	DESK-MX6UL-L 4.0.0 release
2024/07/01	DESK-MX6UL-L 4.1.0 release
2024/10/25	DESK-MX6UL-L 4.2.1 release

Building the Yocto BSP

Quick reference

Repository Information

Repository	Yocto BSP Layer
URL	git@git.dave.eu:desk-mx-l/meta-desk-mx.git
stable branch	kirkstone
stable tag	desk-mx6ul-l-4.1.0

Build targets

Name	Description
dave-image-devel	This image include tools for development/debugging
desk-image-qt6	This image include a Qt6 graphic backend on framebuffer

Introduction

As known, in addition to a bootloader and the o.s. kernel, an embedded Linux system needs a root file system to operate. The root file system must contain everything needed to support the Linux system (applications, settings, data, etc.). The root file system is the file system that is contained on the same partition on which the root directory is located. The Linux kernel, at the end of its startup stage, mounts the root file system on the configured root device and finally launches the /sbin/init, the first user space process and "father" of all the other processes. For more information on the Linux filesystem, please refer to http://www.thegeekstuff.com/2010/09/linux-file-system-structure/.

DESK-MX6UL-L provides one (or more) pre-built root file system, that can be used during the evaluation/development/deployment cycle. For instance, the root file system included in the dave-image-devel image is suited for the development phase, since it provides a relatively rich set of packages including tools and libraries used to debug the application code. The pre-built root file systems are located here: /home/dvdk/desk-mx-l/rfs/<kit_name>.

Besides the pre-built root file systems, DAVE also provides a rich repository containing pre-built applications and libraries. These packages can be easily installed on the target by using the dnf tool. Please refer to this application note for more details.

To generate the supported root file systems, the build of the Yocto BSP has to be run. The output of this process is an image containing the U-Boot binary file, the Linux kernel image, and the selected root file system image. The following sections describe in detail how to execute this operation.

For more general information regarding the Yocto build system, please refer to the dedicated category page.

How to build the Yocto BSP images including the U-Boot binary file, the Linux kernel image, and the target root file system image with KAS

The following procedure requires access to the DAVE Embedded Systems' git repositories. Access to such repositories is granted to the development kit's owners only. Please refer to this page for detailed instructions on how to get it.

This process requires a lot of hardware resources in terms of disk storage, RAM, and processing power. For this reason, it also is recommended to consider the use of a physical machine. For more details on this topic, please refer to the NXP documentation on this BSP, i.e. the i.MX Yocto Project User's Guide, which talks about the host setup for the Yocto build system.

Initialize the build environment

Check that the following packages are installed:

dvdk@vagrant:~$ sudo apt-get update && sudo apt install gawk wget git diffstat unzip texinfo gcc build-essential chrpath socat cpio python3 python3-pip python3-pexpect xz-utils debianutils iputils-ping python3-git python3-jinja2 libegl1-mesa libsdl1.2-dev pylint3 xterm python3-subunit mesa-common-dev zstd liblz4-tool virtualenv 

Before running the build, the KAS environment must be initialized properly.

dvdk@vagrant:~$ virtualenv -p /usr/bin/python3 venv
created virtual environment CPython3.8.10.final.0-64 in 351ms
  creator CPython3Posix(dest=/home/dvdk/venv, clear=False, no_vcs_ignore=False, global=False)
  seeder FromAppData(download=False, pip=bundle, setuptools=bundle, wheel=bundle, via=copy, app_data_dir=/home/dvdk/.local/share/virtualenv)
    added seed packages: pip==24.0, setuptools==69.1.1, wheel==0.42.0
  activators BashActivator,CShellActivator,FishActivator,NushellActivator,PowerShellActivator,PythonActivator
dvdk@vagrant:~$ source venv/bin/activate
(venv) dvdk@vagrant:~$ pip3 install kas==4.2
Collecting kas==4.2
  Downloading kas-4.2.tar.gz (39 kB)
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
  Preparing metadata (pyproject.toml) ... done
Collecting PyYAML<7,>=3.0 (from kas==4.2)
  Using cached PyYAML-6.0.1-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl.metadata (2.1 kB)
Collecting distro<2,>=1.0.0 (from kas==4.2)
  Downloading distro-1.9.0-py3-none-any.whl.metadata (6.8 kB)
Collecting jsonschema<5,>=2.5.0 (from kas==4.2)
  Using cached jsonschema-4.21.1-py3-none-any.whl.metadata (7.8 kB)
Collecting kconfiglib<15,>=14.1.0 (from kas==4.2)
  Downloading kconfiglib-14.1.0-py2.py3-none-any.whl.metadata (39 kB)
Collecting attrs>=22.2.0 (from jsonschema<5,>=2.5.0->kas==4.2)
  Using cached attrs-23.2.0-py3-none-any.whl.metadata (9.5 kB)
Collecting importlib-resources>=1.4.0 (from jsonschema<5,>=2.5.0->kas==4.2)
  Downloading importlib_resources-6.4.0-py3-none-any.whl.metadata (3.9 kB)
Collecting jsonschema-specifications>=2023.03.6 (from jsonschema<5,>=2.5.0->kas==4.2)
  Using cached jsonschema_specifications-2023.12.1-py3-none-any.whl.metadata (3.0 kB)
Collecting pkgutil-resolve-name>=1.3.10 (from jsonschema<5,>=2.5.0->kas==4.2)
  Using cached pkgutil_resolve_name-1.3.10-py3-none-any.whl.metadata (624 bytes)
Collecting referencing>=0.28.4 (from jsonschema<5,>=2.5.0->kas==4.2)
  Downloading referencing-0.34.0-py3-none-any.whl.metadata (2.8 kB)
Collecting rpds-py>=0.7.1 (from jsonschema<5,>=2.5.0->kas==4.2)
  Using cached rpds_py-0.18.0-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl.metadata (4.1 kB)
Collecting zipp>=3.1.0 (from importlib-resources>=1.4.0->jsonschema<5,>=2.5.0->kas==4.2)
  Downloading zipp-3.18.1-py3-none-any.whl.metadata (3.5 kB)
Downloading distro-1.9.0-py3-none-any.whl (20 kB)
Using cached jsonschema-4.21.1-py3-none-any.whl (85 kB)
Downloading kconfiglib-14.1.0-py2.py3-none-any.whl (145 kB)
   ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 145.9/145.9 kB 12.2 MB/s eta 0:00:00
Using cached PyYAML-6.0.1-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (736 kB)
Using cached attrs-23.2.0-py3-none-any.whl (60 kB)
Downloading importlib_resources-6.4.0-py3-none-any.whl (38 kB)
Using cached jsonschema_specifications-2023.12.1-py3-none-any.whl (18 kB)
Using cached pkgutil_resolve_name-1.3.10-py3-none-any.whl (4.7 kB)
Downloading referencing-0.34.0-py3-none-any.whl (26 kB)
Using cached rpds_py-0.18.0-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (1.1 MB)
Downloading zipp-3.18.1-py3-none-any.whl (8.2 kB)
Building wheels for collected packages: kas
  Building wheel for kas (pyproject.toml) ... done
  Created wheel for kas: filename=kas-4.2-py3-none-any.whl size=57786 sha256=919ab9cedc442039708d8846f9fb02e8b43d823cb54d8785737bf46361c594a6
  Stored in directory: /home/dvdk/.cache/pip/wheels/5f/47/a7/e9a292a85a88f96c6b3d834d5e9aceb6927ae2e2b89b123ecb
Successfully built kas
Installing collected packages: zipp, rpds-py, PyYAML, pkgutil-resolve-name, kconfiglib, distro, attrs, referencing, importlib-resources, jsonschema-specifications, jsonschema, kas
Successfully installed PyYAML-6.0.1 attrs-23.2.0 distro-1.9.0 importlib-resources-6.4.0 jsonschema-4.21.1 jsonschema-specifications-2023.12.1 kas-4.2 kconfiglib-14.1.0 pkgutil-resolve-name-1.3.10 referencing-0.34.0 rpds-py-0.18.0 zipp-3.18.1
(venv) dvdk@vagrant:~$

then, create an working directory and fetch the meta-desk-mx repositories with the proper branch:

(venv) dvdk@vagrant:~$ mkdir desk-mx-l/yocto
(venv) dvdk@vagrant:~$ cd desk-mx-l/yocto
(venv) dvdk@vagrant:~/desk-mx-l/yocto$ git clone git@git.dave.eu:desk-mx-l/meta-desk-mx.git -b desk-mx6ul-l-4.2.1

Running the build

Please note that even the basic root file system requires a few hours to build on a mid/hi range desktop (4-6 cores, 8-12 GiB RAM) also depending on your Internet connection speed (all sources are fetched from the network). Nearly 20GiB of disk space is required for the build. The process may be slowed down significantly since the performances of a virtual machine are reduced if compared to the physical hardware. Thus, it's recommended to check the hardware capabilities of the host system and, when building with Yocto is required, to consider the following options:

• Migrating the build system to a physical machine
• Assuming that the host system has the required resources, extending the hardware capabilities of the default MVM (e.g. adding more cores and disk space).

Once the initialization phase, developers can choose the Yocto image to build with KAS

• for example build of dave-image-devel image with DESK-MX6UL-L AxelULite machine and fsl-imx-fb distro, enter the repo directory and

(venv) dvdk@vagrant:~/desk-mx-l/yocto$ cd meta-desk-mx/
(venv) dvdk@vagrant:~/desk-mx-l/yocto/meta-desk-mx$ kas build desk-mx6ul-axelulite_devel_fb.yml

• for example build of dave-image-devel image with DESK-MX6UL-L SBC Rialto machine and fsl-imx-fb distro, enter the repo directory and

(venv) dvdk@vagrant:~/desk-mx-l/yocto$ cd meta-desk-mx/
(venv) dvdk@vagrant:~/desk-mx-l/yocto/meta-desk-mx$ kas build desk-mx6ul-rialto_devel_fb.yml

Once the build process is completed, the resulting files (the U-Boot binaries, the Linux kernel image, the device tree blob, the .tar.gz compressed root file system image, etc.) will be available in build/tmp/deploy/images/<machine_name>.

Generating the SDKs

In way to get the corresponding SDK for QT6, perform the following command:

(venv) dvdk@vagrant:~/desk-mx-l/yocto/meta-desk-mx$ KAS_TASK="populate_sdk" kas build desk-mx6ul-axelulite_qt6_fb.yml

Generating the Toolchain

The toolchain can be created by the following command:

(venv) dvdk@vagrant:~/desk-mx-l/yocto/meta-desk-mx$ KAS_TARGET="meta-toolchain" kas build desk-mx6ul-axelulite_devel_fb.yml

(venv) dvdk@vagrant:~/desk-mx-l/yocto/meta-desk-mx$ KAS_TARGET="meta-toolchain" kas build desk-mx6ul-rialto_devel_fb.yml

Building additional packages

To build additional packages, for example memtester the user need to perform the following command

(venv) dvdk@vagrant:~/desk-mx-l/yocto/meta-desk-mx$ KAS_TARGET="memtester" kas build desk-mx6ul-axelulite_devel_fb.yml

(venv) dvdk@vagrant:~/desk-mx-l/yocto/meta-desk-mx$ KAS_TARGET="memtester" kas build desk-mx6ul-rialto_devel_fb.yml

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