On this page:
- Building NXP/Embedian’s Yocto real-time Kirkstone BSP Distribution
- Introduction
- Generating SSH Keys
- Overview of the meta-embedian Yocto Layer
- Setting Up the Tools and Build Environment
- Setup microSD Card Manually
- Install Root File System
- Setup microSD Card Automatically
- Feed Packages
- Writing Bitbake Recipes
- Setup eMMC Manually
- Install Root File System
- Setup eMMC Automatically
- Video Decoding
- WiFi
Building NXP/Embedian’s Yocto real-time Kirkstone BSP Distribution
Eric Lee
version 1.0a, 10/29/2024
Introduction
This document describes how Embedian builds a customized version of real-time edge NXP’s i.MX8M Plus (8MP) official Yocto Kirkstone BSP release for Embedian's pITX-MX8M-PLUS product platform. It is for application that requires mission critical. The approach is to pull from Embedian's public facing GIT repository and build that using bitbake. The reason why we use this approach is that it allows co-development. The build output is comprised of binary images, feed packages, and an SDK for pITX-MX8M-PLUS specific development.
NXP makes their i.MX series official bsp build scripts available via the following GIT repository:
NXP makes their real-time-edge official meta-layer available via the following GIT repository:
Freescale community BSP release build script is available via the following repository:
It is this repository that actually pulls in the meta-imx/meta-bsp project to perform the Linux BSP builds for NXP's i.MX8MP ARM Cortext-A53 chips.
Generating SSH Keys
We recommend you use SSH keys to establish a secure connection between your computer and Embedian Gitlab server. The steps below will walk you through generating an SSH key and then adding the public key to our Gitlab account.
Step 1. Check for SSH keys
First, we need to check for existing ssh keys on your computer. Open up Git Bash and run:
Check the directory listing to see if you have a file named either id_rsa.pub or id_dsa.pub. If you don't have either of those files go to step 2. Otherwise, you already have an existing keypair, and you can skip to step 3.
Step 2. Generate a new SSH key
To generate a new SSH key, enter the code below. We want the default settings so when asked to enter a file in which to save the key, just press enter.
Step 3. Add your SSH key to Embedian Gitlab Server
Copy the key to your clipboard.
Go to Embedian Git Server. At Profile Setting --> SSH Keys --> Add SSH Key
Paste your public key and press "Add Key" and your are done.
Overview of the meta-embedian Yocto Layer
The supplied meta-embedian Yocto compliant layer has the following organization:
Notes on meta-embedian layer content
conf/machine/*
This folder contains the machine definitions for all Embedian's platform and backup repository in Embedian. These select the associated kernel, kernel config, u-boot, u-boot config, and tar.bz2 image settings.
recipes-bsp/u-boot/*
This folder contains recipes used to build DAS U-boot for all Embedian's platform.
recipes-bsp/imx-atf/*
This folder contains recipes used to enable console port for Embedian's i.MX8MM platform.
recipes-bsp/imx-sc-firmware/*
This folder contains system control firmware binary for Embedian's i.MX8QM platform.
recipes-bsp/alsa-state/*
This folder contains sgtl5000 sound chip default state for all Embedian's platform.
recipes-bsp/imx-mkimage/*
This folder contains imx-mkimage tool for Embedian's i.MX8MQ, i.MX8MM, i.MX8QM, i.MX8MP platform.
recipes-core/busybox/*
This folder remove telnetd from bysybox for all Embedian's platform.
recipes-core/psplash/*
This folder customized Yocto boot psplash for all Embedian's platform.
recipes-kernel/linux/*
Contains the recipes needed to build for all Embedian's platform Linux kernels.
recipes-nxp/images/*
Remove the packages that broken the building process and do not need for real-time-edge rootfs.
Setting Up the Tools and Build Environment
To build the latest NXP i.MX8M Plus meta-bsp, you first need an Ubuntu 20.04 or 22.04 LTS installation. Since bitbake does not accept building images using root privileges, please do not login as a root user when performing the instructions in this section.
Once you have Ubuntu 20.04 or 22.04 LTS running, install the additional required support packages using the following console command:
To get the BSP you need to have 'repo' installed and use it as:
Install the 'repo' utility:
Download the BSP Yocto Project Environment.
Download the Embedian Yocto build script and meta layer.
Choose "y" to accept EULA.This script will create and bring you to ~/real-time-edge/build-imx-real-time-edge directory.
Building the target platforms
To build Embedian/NXP Yocto BSP, use the following commands:
Once it done, you can find all required images under ~/real-time-edge/<build directory>/tmp/deploy/images/<machine name>/
You may want to build programs that aren’t installed into a root file system so you can make them available via a feed site (described below.) To do this you can build the package directly and then build the package named package-index to add the new package to the feed site.
The following example builds the tcpdump program and makes it available on the feed site:
Once the build(s) are completed you’ll find the resulting images, rpm and licenses in folder
~/real-time-edge/<build directory>/tmp/deploy.deploy/images/<machine name>/*
This folder contains the binary images for the root file system and the Embedian pITX-MX8M-PLUS specific version of the boot file, Image and device tree file. Specifically the images are:
deploy/images/<machine name>/imx-boot-<machine name>-sd.bin-flash_evk
This is boot file binary for pITX-MX8M-PLUS.
deploy/images/<machine name>/Image
The kernel Image for pITX-MX8M-PLUS.
deploy/images/<machine name>/<device tee file>
Selecting display configuration is a matter of selecting an appropriate DTB file under deploy/images/<machine name>/<device tee file>
All available DTB files are listed in the table below.
| DTB File Name | Description |
|---|---|
imx8mp-pitx.dtb | Device tree blob for no display configuration. |
imx8mp-pitx-hdmi.dtb | Device tree blob for HDMI display configuration. |
imx8mp-pitx-lvds.dtb | Device tree blob for LVDS display configuration. |
imx8mp-pitx-m7.dtb | Device tree blob for Cortex-M7 co-processor configuration. |
deploy/images/<machine name>/fsl-image-validation-imx-<machine name>.*
Embedian root file system images for software development on Embedian’s pITX-MX8M-PLUS platforms without QT6.
deploy/images/<machine name>/fsl-image-qt6-validation-imx-<machine name>.*
Embedian root file system images for software development on Embedian’s pITX-MX8M-PLUS with QT6.
deploy/deb/*
This folder contains all the packages used to construct the root file system images. They are in deb format (similar format to Debian packages) and can be dynamically installed on the target platform via a properly constructed feed file. Here is an example of the feed file (named base- feeds.conf) that is used internally at Embedian to install upgrades onto a pITX-MX8M-PLUS platform without reflashing the file system:
deploy/licenses/* A database of all licenses used in all packages built for the system.
Setup microSD Card Manually
For these instruction, we are assuming: DISK=/dev/mmcblk0, "lsblk" is very useful for determining the device id.
Erase microSD card:
Create Partition Layout: Leave 1MB offset for boot file.
With util-linux v2.26, sfdisk was rewritten and is now based on libfdisk.
Create Partitions:
Format Partitions:
Mount Partitions:
On some systems, these partitions may be auto-mounted...
Install Boot File (imx-boot-<machine name>-sd.bin-flash_evk)
Boot file is factory default flashed at on-module eMMC flash.
If on-module eMMC Flash is empty
In some cases, when eMMC flash is erased or the u-boot is under development, we need a way to boot from microSD card first. Users need to set port 1-3 of SW2 to ON ON ON. In this way, pITX-MX8M-PLUS will always boot up from microSD card.
Fuse flash.bin to the microSD card.
If on-module eMMC Flash is not empty
The <boot file> is pre-installed in on-module eMMC flash at factory default. pITX-MX8M-PLUS is designed to always boot up from on-module eMMC flash and to load Image, device tree blob and root file systems based on the setting of SW2 port 1-3. If users need to fuse your own flash.bin or perform u-boot upgrade. This section will instruct you how to do that.
Copy <boot file> to the second partition home directory of your microSD card and boot into microSD card. Go to home directory and you should see flash.bin file.
Fuse <boot file> to the on-module eMMC flash. (The eMMC flash is emulated as /dev/mmcblk2 in pITX-MX8M-PLUS)
uEnv.txt based bootscript
Create "uEnv.txt" boot script: ($ vim uEnv.txt)
Copy uEnv.txt to the boot partition:
Install Kernel Image
Copy Image to the boot partition:
Install Kernel Device Tree Binary
All available DTB files are listed in the table below.
| DTB File Name | Description |
|---|---|
imx8mp-pitx.dtb | Device tree blob for no display configuration. |
imx8mp-pitx-hdmi.dtb | Device tree blob for HDMI display configuration. |
imx8mp-pitx-lvds.dtb | Device tree blob for LVDS display configuration. |
imx8mp-pitx-m7.dtb | Device tree blob for Cortex-M7 co-processor configuration. |
Install Root File System
Copy Root File System:
Yocto Built Rootfs:
Remove microSD card:
Setup microSD Card Automatically
This section tells you how to set up an microSD card automatically. It mainly uses a script to do all the steps in the above section.
Set SW2 port 1-3 as (ON ON ON). The module will boot up from microSD card.
Feed Packages
You need to setup Apache2 web server on your development host machine first.
The Apache server default web page directory is /var/www/html .We need to populate it with a link pointing to our deb package repository.
The following procedure can be used on a Embedian pITX-MX8M-PLUS device to download and utilize the feed file show above to install the tcpdump terminal emulation program:
Writing Bitbake Recipes
In order to package your application and include it in the root filesystem image, you must write a BitBake recipe for it.
When starting from scratch, it is easiest to learn by example from existing recipes.
Example HelloWorld recipe using autotools
For software that uses autotools (./configure; make; make install), writing recipes can be very simple:
DESCRIPTION = "Hello World Recipe using autotools"HOMEPAGE = "http://www.embedian.com/"SECTION = "console/utils"PRIORITY = "optional"LICENSE = "GPL"PR = "r0" S = "${WORKDIR}/git" inherit autotools |
SRC_URI specifies the location to download the source from. It can take the form of any standard URL using http://, ftp://, etc. It can also fetch from SCM systems, such as git in the example above.
PR is the package revision variable. Any time a recipe is updated that should require the package to be rebuilt, this variable should be incremented.
inherit autotools brings in support for the package to be built using autotools, and thus no other instructions on how to compile and install the software are needed unless something needs to be customized.
S is the source directory variable. This specifies where the source code will exist after it is fetched from SRC_URI and unpacked. The default value is ${WORKDIR}/${PN}-${PV}, where PN is the package name and PV is the package version. Both PN and PV are set by default using the filename of the recipe, where the filename has the format PN_PV.bb.
Example HelloWorld recipe using a single source file
This example shows a simple case of building a helloworld.c file directly using the default compiler (gcc). Since it isn’t using autotools or make, we have to tell BitBake how to build it explicitly.
DESCRIPTION = "HelloWorld"SECTION = "examples"LICENSE = "GPL" SRC_URI = "file://helloworld.c" S = "${WORKDIR}" do_compile() { ${CC} ${CFLAGS} ${LDFLAGS} helloworld.c -o helloworld} do_install() { install -d ${D}${bindir} install -m 0755 helloworld ${D}${bindir}} |
In this case, SRC_URI specifies a file that must exist locally with the recipe. Since there is no code to download and unpack, we set S to WORKDIR since that is where helloworld.c will be copied to before it is built.
WORKDIR is located at ${OETREE}/<build directory>/tmp/work/armv8a-poky-linux/<package name and version> for most packages. If the package is machine-specific (rather than generic for the armv8a architecture), it may be located in the pitximx8mp4g-poky-linux subdirectory depending on your hardware (this applies to kernel packages, images, etc).
do_compile defines how to compile the source. In this case, we just call gcc directly. If it isn’t defined, do_compile runs make in the source directory by default.
do_install defines how to install the application. This example runs install to create a bin directory where the application will be copied to and then copies the application there with permissions set to 755.
D is the destination directory where the application is installed to before it is packaged.
${bindir} is the directory where most binary applications are installed, typically /usr/bin.
For a more in-depth explanation of BitBake recipes, syntax, and variables, see the Recipe Chapter of the OpenEmbedded User Manual.
Setup eMMC Manually
Setting up eMMC usually is the last step at development stage after the development work is done at your microSD card or NFS environments. From software point of view, eMMC is nothing but a non-removable microSD card on board. For pITX-MX8M-PLUS, the microSD card is always emulated as /dev/mmcblk1 and on-module eMMC is always emulated as /dev/mmcblk2. Setting up eMMC now is nothing but changing the device descriptor.
This section gives a step-by-step procedure to setup eMMC flash. Users can write a shell script your own at production to simplify the steps.
First, we need to backup the final firmware from your microSD card or NFS.
Prepare for eMMC binaries from microSD card (or NFS):
Insert microSD card into your Linux PC. For these instructions, we are assuming: DISK=/dev/mmcblk0, "lsblk" is very useful for determining the device id.
For these instruction, we are assuming: DISK=/dev/mmcblk0, "lsblk" is very useful for determining the device id.
Mount Partitions:
On some systems, these partitions may be auto-mounted...
Copy Image to rootfs partition:
Copy uEnv.txt to rootfs partition:
Copy and paste the following contents to /media/rootfs/home/root ($ sudo vim /media/rootfs/home/root/uEnv.txt)
Copy device tree blob to rootfs partition:
Copy boot file to rootfs partition:
Copy real rootfs to rootfs partition:
Remove microSD card:
Copy Binaries to eMMC from microSD card:
Insert this microSD card into your pITX-MX8M-PLUS device.
Now it will be almost the same as you did when setup your microSD card, but the eMMC device descriptor is /dev/mmcblk2 now. Booting up the device.
Erase eMMC:
Create Partition Layout:
Format Partitions:
Mount Partitions:
Install binaries for partition 1
Copy uEnv.txt/Image/*.dtb to the boot partition
Install Kernel Device Tree Binary
Install Root File System
Unmount eMMC:
Flash boot file
Switch your Boot Select to eMMC ((SW2 port 1-3 is (OFF ON OFF) ) and you will be able to boot up from eMMC now.
Setup eMMC Automatically
Boot up the module from microSD card and run the following script. The Yocto images will be written into on-module eMMC.
Shutdown the device. Set SW2 port 1-3 as (OFF ON OFF). The module will boot up from on-module eMMC.
Video Decoding
For playing video, we can use three solutions to support it.
a) # gplay-1.0 <video file>
b) # gst-launch-1.0 playbin uri=file://<video absolute path>
c) ( i ) if video container on .mp4 format
# gst-launch-1.0 filesrc location=<file name.mp4> typefind=true ! video/quicktime ! qtdemux ! queue max-size-time=0 ! vpudec ! queue max-size-time=0 ! kmssink force-hantrope=true sync=false &
( ii ) if video container on .ts format
# gst-launch-1.0 filesrc location=<file name.ts> typefind=true ! video/mpegts ! tsdemux ! queue max-size-time=0 ! vpudec ! queue max-size-time=0 ! waylandsink
WiFi
The BSP includes NXP 88W8997 wifi chipset. Users can choose mPCIe or M.2 key E form factor wifi modules based on NXP 88W8997 chipset.
M.2 Form Factor:
AzureWave P/N: AW-CM276MA-PURLaird Connectivity P/N: 60-2230CEmbedded Artists 1YM M.2 Module
mPCIe Factor:
Globascale Technologies NXP 88W8997 2x2 WiFi 802.11ac+BT 5.0 mini PCIe Card w/ Two External SMA Antennas
Boot up the device and load the driver modules in the kernel.
Verify that the module is now visible to the system.
In case you need to see which network and you can scan it and select the one you need.
Identify the network and add it to the WPA supplicant file.
Associate the Wi-Fi with config
Check if you have right SSID associated.
Use DHCP to get IP
You should be able to ping local network now.
Modify /etc/resolv.conf of your preference, you will be able to ping out.
version 1.0a, 10/29/2024
Last updated 2024-10-29