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Mind Chasers Inc.

Build, Install, and Develop with NXP's Latest Yocto Linux BSP for the MCIMX8M-EVK

We show how to build the latest NXP Yocto BSP for the NXP MCIMX8M-EVK evaluation kit for the i.MX 8MQuad processor

X-ray Engineering Services


NXP has recently updated their MCIMX8M-EVK Yocto BSP to the Linux L5.15.32 kernel. We have found that some of NXP's Yocto Linux related documentation is confusing, so we have developed this article about how we perform basic development steps with the Yocto Project, Linux kernel, and user space in the context of our i.MX8 EVK.

The steps shown below can be followed to create a working EVK system from source using an Ubuntu host as the Yocto build machine (and package server).

The Yocto Project itself has fantastic documentation, and there is a lot of it! If you're new to Yocto Project, then start with the Quick Build Guide. And don't overlook What I Wish I'd Known.

Listed below are some of the data points that we need to establish to move forward when building a Yocto image from source for our EVK:

  • The NXP i.MX 8MQuad is powered by a quad core 1.5 GHz ARM CORTEX-A53 with an auxiliary ARM M4
  • We are working with the NXP L5.15.32-2.0.0 release. This was developed using the Yocto Project Kirkstone (4.0) branch / release.
  • Kirkstone 4.0 was released May 2022 and is considered a Long Term Support release, which will be supported at least through April 2024.
  • We utilize the Wayland graphics back end. XWayland is also supported (Wayland with X11 support) by the BSP.
  • Our Yocto Machine: imx8mqevk
  • Our Yocto distro: "fsl-imx-wayland"
  • There is an EVKB and EVK. We are using the EVKB, and this has an upgrade to the WIFI over the EVK and a later revision of the i.MX8 SoC.
EVK Board

Initial Steps

As recommended by NXP, we're using the repo tool, which is a Python script developed by Google to pull all the necessary Git repositories at the correct commits based on NXP's GA release manifest. Refer to NXP's "i.MX Repo Manifest" README for additional details.

Below we install NXP's Yocto Project release in our /build/imx8/ folder:

$ mkdir -p /build/imx8; cd /build/imx8
$ repo init -u https://source.codeaurora.org/external/imx/imx-manifest -b imx-linux-kirkstone -m imx-5.15.32-2.0.0.xml

Downloading Repo source from https://gerrit.googlesource.com/git-repo
Downloading manifest from https://source.codeaurora.org/external/imx/imx-manifest
repo has been initialized in /build/imx8

$ ls -a
.  ..  .repo

$ repo sync
repo sync has finished successfully.

$ ls
imx-setup-release.sh  README  README-IMXBSP  setup-environment  sources

$ ls sources/
base          meta-clang      meta-freescale-3rdparty  meta-imx                  meta-openembedded  meta-timesys         poky
meta-browser  meta-freescale  meta-freescale-distro    meta-nxp-demo-experience  meta-qt6           meta-virtualization

Create our Yocto Project build environment under the folder bld-wayland:

$ DISTRO=fsl-imx-wayland MACHINE=imx8mqevk source imx-setup-release.sh -b bld-wayland
Your build environment has been configured with:

Your build environment has been configured with:

meta-freescale directory found

$ pwd 

$ tree
└── conf
    ├── bblayers.conf
    ├── bblayers.conf.org
    ├── local.conf
    ├── local.conf.org
    ├── local.conf.sample
    └── templateconf.cfg

Using another shell, let's take a look at the meta-sdk folder:

$ cd /build/imx8/sources/meta-imx/meta-sdk/recipes-fsl/images

$ ls *.bb
fsl-image-gui.bb  fsl-image-validation-imx.bb  imx-image-core.bb  imx-image-multimedia.bb

And it may be instructive to realize that the Git repositories under sources are not on a branch and may have been modified during the previous setup:

$ git branch
* (no branch)

$ git log
commit 5bc708f56575a878da17f2148e959c95d06cf8db (HEAD, tag: rel_imx_5.15.32_2.0.0, m/imx-linux-kirkstone, CAF/kirkstone-5.15.32-2.0.0)
Author: Jun Zhu 
Date:   Thu Jul 7 22:22:03 2022 -0700

    tensorflow-lite-extras_git.bb: Update to commit f6caf10
    - Update to new commit for 5.15.32-2.0.0 release
    - Use lfs=0 to disable error during do_fetch

The bitbake command below will build an sdcard image in the deploy folder that we can use to boot our NXP EVK. Return to our original build shell:

$ bitbake imx-image-multimedia


Build Configuration:
BB_VERSION           = "2.0.0"
BUILD_SYS            = "x86_64-linux"
NATIVELSBSTRING      = "universal"
TARGET_SYS           = "aarch64-poky-linux"
MACHINE              = "imx8mqevk"
DISTRO               = "fsl-imx-wayland"
DISTRO_VERSION       = "5.15-kirkstone"
TUNE_FEATURES        = "aarch64 armv8a crc crypto"
TARGET_FPU           = ""
meta-poky            = "HEAD:27de52e402ae000dfa502d52908cd6e6aef923ec"
meta-python          = "HEAD:5357c7a40eaf8d1bcf7ff58edbba8e9527e40c7d"
meta-freescale       = "HEAD:2fb1ce365338126aad365012ebb913b3e4a9f1be"
meta-freescale-3rdparty = "HEAD:de0eb1408150d77f9cce97c559f9a5a3c71e5d6c"
meta-freescale-distro = "HEAD:fc15f5003043da23212596be7366ae2547c308ad"
meta-v2x             = "HEAD:5bc708f56575a878da17f2148e959c95d06cf8db"
meta-nxp-demo-experience = "HEAD:8fade3993b832ecd823771644f2a7b731f8f4527"
meta-chromium        = "HEAD:d25d8ee98a656b2534d0eec6138ef264529fab4f"
meta-clang           = "HEAD:85d956d95401479ca666139e31f662f60c156d5f"
meta-filesystems     = "HEAD:5357c7a40eaf8d1bcf7ff58edbba8e9527e40c7d"
meta-qt6             = "HEAD:b2894aad5c1aaa85f2f5c7b94391b7c51c39e555"
meta-virtualization  = "HEAD:973c8d0964c6f40338857efe5b8009b2f647d485"

WARNING: tesseract-lang-4.1.0-r0 do_fetch: Failed to fetch URL git://github.com/tesseract-ocr/tessdata.git;branch=master;protocol=https, attempting MIRRORS if available
WARNING: imx-image-multimedia-1.0-r0 do_rootfs: QA Issue: The license listed BSD was not in the licenses collected for recipe sigma-dut [license-file-missing]
WARNING: imx-image-multimedia-1.0-r0 do_rootfs: QA Issue: The license listed BSD was not in the licenses collected for recipe sudo [license-file-missing]
WARNING: imx-image-multimedia-1.0-r0 do_rootfs: QA Issue: The license listed BSD was not in the licenses collected for recipe sudo [license-file-missing]
WARNING: imx-image-multimedia-1.0-r0 do_rootfs: QA Issue: The license listed BSD was not in the licenses collected for recipe sudo [license-file-missing]
WARNING: imx-image-multimedia-1.0-r0 do_rootfs: QA Issue: The license listed BSD was not in the licenses collected for recipe wireless-tools [license-file-missing]

When we want to come back to the build system, we can do the following:

$ cd /build/imx8

$ source sources/poky/oe-init-build-env bld-wayland/

### Shell environment set up for builds. ###

You can now run 'bitbake <target>'

Common targets are:

You can also run generated qemu images with a command like 'runqemu qemux86'

Other commonly useful commands are:
 - 'devtool' and 'recipetool' handle common recipe tasks
 - 'bitbake-layers' handles common layer tasks
 - 'oe-pkgdata-util' handles common target package tasks

$ bitbake imx-image-multimedia

Burning our *.wic image on an SD Card

Let's first take a look at the image file system types we have configured:

$ bitbake imx-image-multimedia -e | grep ^IMAGE_FSTYPES
IMAGE_FSTYPES="wic.bmap  wic.bz2 tar.bz2"

We decompress the *wic.bz2 file before writing our SD Card. We run the following in our Ubuntu shell on our build machine:

$ cd /build/imx8/bld-wayland/tmp/deploy/images/imx8mqevk/

$ ls *.bz2
imx-image-multimedia-imx8mqevk-20220711122450.rootfs.tar.bz2  imx-image-multimedia-imx8mqevk.tar.bz2
imx-image-multimedia-imx8mqevk-20220711122450.rootfs.wic.bz2  imx-image-multimedia-imx8mqevk.wic.bz2

$ bunzip2 -vfk imx-image-multimedia-imx8mqevk.wic.bz2

file imx-image-multimedia-imx8mqevk.wic
imx-image-multimedia-imx8mqevk.wic: DOS/MBR boot sector; 
partition 1 : ID=0xc, active, start-CHS (0x80,0,1), end-CHS (0x3ff,3,32), startsector 16384, 170392 sectors; 
partition 2 : ID=0x83, start-CHS (0x3ff,3,32), end-CHS (0x3ff,3,32), startsector 196608, 8444606 sectors

Note that the resulting *.wic image is ~3.5GB, but we expect this to grow significantly once we add a toolchain and other packages.

Our next step is to program our SD Card, which is inserted but not mounted in our Ubuntu host:

$ sudo fdisk /dev/mmcblk0

Welcome to fdisk (util-linux 2.31.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Command (m for help): p

Disk /dev/mmcblk0: 29.7 GiB, 31914983424 bytes, 62333952 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xa0a5537f

Let's use dd to write our wic file to our SD Card.

$ sudo dd if=imx-image-multimedia-imx8mqevk.wic of=/dev/mmcblk0 bs=1M status=progress
2746220544 bytes (2.7 GB, 2.6 GiB) copied, 1 s, 2.7 GB/s
4219+1 records in
4219+1 records out
4424301568 bytes (4.4 GB, 4.1 GiB) copied, 182.402 s, 24.3 MB/s

Let's take a look at what we just did. As you can see below, this process created two partitions (as expected).

$ sudo fdisk -l /dev/mmcblk0

Disk /dev/mmcblk0: 29.7 GiB, 31914983424 bytes, 62333952 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xa0a5537f

Device         Boot  Start     End Sectors  Size Id Type
/dev/mmcblk0p1 *     16384  186775  170392 83.2M  c W95 FAT32 (LBA)
/dev/mmcblk0p2      196608 8641213 8444606    4G 83 Linux

Note that we can also insert our programmed SD Card back into our Ubuntu host later and make changes to the partitions and their contents.

Notes on Directories and Source

imx-image-multimedia.bb can be found in sources/meta-imx/meta-sdk/recipes-fsl/images

As you may have noticed, there are several NXP layers under sources. Here's one way to determine where a recipe is located:

$ cd /build/imx8/sources/
$ find . -name 'linux-imx*bb'

We can see above that the linux-imx_5.15 recipe is located in the meta-imx/meta-bsp layer. This makes sense since NXP tells us that the purpose of this layer is to introduce new features into the Yocto Project build that might not have been availble for the Yocto Kirkstone release.

View the manifest:

$ cd /build/imx8/bld-wayland/tmp/deploy/images/imx8mqevk

$ more imx-image-multimedia-imx8mqevk.manifest | more
acl armv8a 2.3.1-r0
adwaita-icon-theme-symbolic all 41.0-r0
alsa-conf armv8a-mx8m
alsa-plugins-pulseaudio-conf armv8a 1.2.6-r0
alsa-state imx8mqevk 0.2.0-r5
alsa-states imx8mqevk 0.2.0-r5
alsa-tools armv8a 1.2.5-r0
alsa-topology-conf all
alsa-ucm-conf all

It can be confusing trying to determine where the source is hosted that is used to build our image. One way of determining this is shown below:

$ cd /build/imx8/bld-wayland/tmp/work/

$ ls
all-poky-linux  armv8a-mx8m-poky-linux  armv8a-poky-linux  imx8mqevk-poky-linux  x86_64-linux

$ grep url imx8mqevk-poky-linux/linux-imx/5.15.32+gitAUTOINC+fa6c316859-r0/git/.git/config 
	url = https://source.codeaurora.org/external/imx/linux-imx.git
$ grep url imx8mqevk-poky-linux/u-boot-imx/2022.04-r0/git/.git/config
	url = https://source.codeaurora.org/external/imx/uboot-imx.git

Remote login via SSH

We find that our EVK Linux image supports Ethernet connectivity without requiring customization.

After boot up of our EVK and determination of our EVK's IP address, we add the IP address for the EVK board to /etc/hosts and login remotely:

ssh root@evk
The authenticity of host 'evk (' can't be established.
RSA key fingerprint is SHA256:ZOx862o0VxZf4NOaqEHROt9pU+mb4cN3t0VyvkIxffg.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'evk,<ip address>' (RSA) to the list of known hosts.

# uname -a
Linux imx8mqevk 5.15.32-lts-next+gfa6c3168595c #1 SMP PREEMPT Tue Jun 7 02:34:46 UTC 2022 aarch64 aarch64 aarch64 GNU/Linux

# cat /proc/cpuinfo 
processor	: 0
BogoMIPS	: 16.66
Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 cpuid
CPU implementer	: 0x41
CPU architecture: 8
CPU variant	: 0x0
CPU part	: 0xd03
CPU revision	: 4

processor	: 1

processor	: 2

processor	: 3

DNF and package management

We add DNF package management support to our EVK target and build machine following Yocto documentation and our article "Use DNF Package Manager on a Yocto Linux Development System"

When we're done, our conf/local.conf file looks like below:

MACHINE ??= 'imx8mqevk'
DISTRO ?= 'fsl-imx-wayland'
PACKAGE_CLASSES ?= 'package_rpm'
EXTRA_IMAGE_FEATURES ?= "debug-tweaks"
USER_CLASSES ?= "buildstats"
    STOPTASKS,${DL_DIR},1G,100K \
    STOPTASKS,/tmp,100M,100K \
    HALT,${TMPDIR},100M,1K \
    HALT,${DL_DIR},100M,1K \
    HALT,${SSTATE_DIR},100M,1K \
PACKAGECONFIG:append:pn-qemu-system-native = " sdl"

DL_DIR ?= "${BSPDIR}/downloads/"

EXTRA_IMAGE_FEATURES += "package-management"

After rebuilding, don't forget to run "bitbake package-index" on the build machine. Next, on our EVK, we run:

# dnf makecache
timer: config: 11 ms
DNF version: 4.2.2
Command: dnf makecache 
Installroot: /
Releasever: zeus
cachedir: /var/cache/dnf
Base command: makecache
Extra commands: ['makecache']
Repository 'oe-packages' is missing name in configuration, using id.
Making cache files for all metadata files.
oe-packages: has expired and will be refreshed.
repo: downloading from remote: oe-packages
oe-packages: using metadata from Sun Jun 20 14:08:43 2021.
Last metadata expiration check: 0:00:04 ago on Sun Jun 20 14:53:21 2021.
No module defaults found
timer: sack setup: 3798 ms
Metadata cache created.
Cleaning up.

Adding the GNU Toolchain to our target

We add "tools-sdk" to our IMAGE_FEATURES variable to install a full SDK on our target. After modifying IMAGE_FEATURES, we re-run our build and inspect our updated rootfs:

$ bitbake imx-image-multimedia

$ cd /build/imx8/bld-wayland/tmp/work/imx8mqevk-poky-linux/imx-image-multimedia/1.0-r0/rootfs

$ find . -name autoconf

$ find . -name gcc

Let's also take a look at the updated manifest after updating the package-index:

$ bitbake package-index

$ cd /build/imx8/bld-wayland/tmp/deploy/images/imx8mqevk/

grep autoconf grep autoconf imx-image-multimedia-imx8mqevk.manifest 
autoconf aarch64 2.69

$ grep cmake imx-image-multimedia-imx8mqevk.manifest

As you can see above, cmake isn't included in the SDK, so let's add it by using dnf as described above:

build server:

$ bitbake cmake
$ bitbake package-index

imx shell:

# dnf makecache 
# dnf install cmake

Cleaning up. 

# cmake --version
cmake version 3.15.3

CMake suite maintained and supported by Kitware (kitware.com/cmake).

Obviously, creating customizations to an SD Card partition that will be later overwritten might not be what we want. We may want to move our rootfs off of the SD Card (i.e., use an NFS mount)

In Part 2 of this article we'll discuss topics like building the Linux Kernel outside of Yocto using a Yocto generated SDK and booting our EVK via TFTP and NFS.

References and Resources

Acronyms and Terms

  • SRC: i.MX8 System Reset Controller

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