DESK-MX8M-L/Development/Building the Yocto BSP

History
ID#	Issue Date	Notes
16113	16/02/2022	First DESK-MX8M-L release
17543	24/02/2023	DESK-MX8M-L-2.0.0 release
17543	25/07/2023	DESK-MX8M-L-4.0.0 release

Building the Yocto BSP

Quick reference

Repository Information
Repository	BSP Manifest	Yocto BSP Layer
URL	git@git.dave.eu:desk-mx-l/desk-mx-l-bsp.git	git@git.dave.eu:desk-mx-l/meta-desk-mx.git
stable branch	desk-mx8m-l-4.x.x	desk-mx8m-l-4.x.x
stable tag	desk-mx8m-l-4.0.0	desk-mx8m-l-4.0.0

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-MX8M-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 desk-mx8m-l-4.x.x-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/<target_name>/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 apt-get 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 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

The following procedure requires the access to the DAVE Embedded Systems' git repositories. The access to such repositories is granted to 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

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

DESK-MX8M-L Yocto BSP uses git-repo tool to fetch all the required git repositories. To install it, please use the following commands:

dvdk@vagrant:~$ mkdir -p ~/desk-mx-l/yocto
dvdk@vagrant:~$ cd ~/desk-mx-l/yocto
dvdk@vagrant:~/desk-mx-l/yocto$ curl http://commondatastorage.googleapis.com/git-repo-downloads/repo-1 > repo
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 29945  100 29945    0     0  64816      0 --:--:-- --:--:-- --:--:-- 64676
dvdk@vagrant:~/desk-mx-l/yocto$ chmod a+x repo

then, fetch the Yocto repositories with the proper branch:

dvdk@vagrant:~/desk-mx-l/yocto$ ./repo init -u git@git.dave.eu:desk-mx-l/desk-mx-l-bsp.git -b refs/tags/desk-mx8m-l-4.0.0
dvdk@vagrant:~/desk-mx-l/yocto$ ./repo sync -c

In case of ca-certificates failures, which may appears during https access to some repo:

 Fetching projects:  11% (2/17) meta-freescale-3rdpartyfatal: unable to access 'https://source.codeaurora.org/external/imxsupport/meta-nxp-demo-experience/': server certificate verification failed. CAfile: /etc/ssl/certs/ca-
 certificates.crt CRLfile: none
 fatal: unable to access 'https://git.openembedded.org/meta-python2/': server certificate verification failed. CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none
 fatal: unable to access 'https://source.codeaurora.org/external/imxsupport/meta-nxp-demo-experience/': server certificate verification failed. CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none
 fatal: unable to access 'https://git.openembedded.org/meta-python2/': server certificate verification failed. CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none
 error: Cannot fetch meta-nxp-demo-experience from https://source.codeaurora.org/external/imxsupport/meta-nxp-demo-experience

a possible solution is to disable the SSL verification setting:

<pre class="workstation-terminal">
dvdk@vagrant:~/desk-mx-l/yocto$ export GIT_SSL_NO_VERIFY=1

Initialize DISTRO and MACHINE

Select the Weston backend (you will be asked to accept the EULA):

dvdk@vagrant:~/desk-mx-l/yocto$ DISTRO=fsl-imx-wayland MACHINE=desk-mx8mp source desk-setup-release.sh -b build-wayland
...
Do you accept the EULA you just read? (y/n) y                                                                   
EULA has been accepted.                                                                                                
                                                                                                                       
Welcome to Freescale Community BSP
...
dvdk@vagrant:~/desk-mx-l/yocto/build-wayland$

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 completed the initialization phase, developers can launch the Yocto image build process with the following commands:

dvdk@vagrant:~/desk-mx-l/yocto/build-wayland$ bitbake dave-image-devel

Where dave-image-devel is one of the images listed in here.

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

After creating an image as described in the previous version, the corresponding SDK can be generated by issuing the following command:

bitbake dave-image-devel -c populate-sdk

Again, replace dave-image-devel with one of the images listed in here.

Building additional packages

To build additional packages the user must select the DISTRO and source the desk-setup-release.sh script

dvdk@vagrant:~/desk-mx-l/yocto$ DISTRO=fsl-imx-wayland MACHINE=desk-mx8mp source desk-setup-release.sh -b build-wayland
dvdk@vagrant:~/desk-mx-l/yocto/build-wayland$

And then can run any of the bitbake command.

dvdk@vagrant:~/desk-mx-l/yocto/build-wayland$ bitbake memtester

The resulting packages (the default format is rpm) can be found inside build/tmp/deploy/rpm.

---