i.MX 93 EVK debug console relocation [Continued]

Introduction.

This is an update to the previous article i.MX 93/91 debug console relocation with Yocto Project. It was initiated because a customer wanted to replicate the mentioned document in newer BSPs.

i.MX93EVK uses LPUART1 as the debug console, this article will contribute to relocate debug console to LPUART2, which is connected to USB-to-UART FTDI bridge, so it's very easy to confirm your changes.

Key differences from the past article are we don't explore porting tools but provide specific instructions and code, you will follow this article to confirm changes made on your own or replicate this process, if you want to explore BSP customizing tools and process, review the other article. BSP version is LF-6.12.49 Yocto Walnascar. HW setup simplifies too.

1. Hardware Setup.

i.MX93EVK featuring REV A1.
Connect USB Type-C PD power source to J301.
Connect USB type-C cable to USB debug J1401.
Connect USB type-C cable to USB1 J401.
[Optional] SD card for booting, eMMC is the other option.

2. Yocto Project setup for recipes development.

Start by creating a fresh build.

$ cd ~
$ mkdir Yocto-BSP
$ cd Yocto-BSP
$ repo init -u https://github.com/nxp-imx/imx-manifest -b imx-linux-walnascar -m imx-6.12.49-2.2.0.xml
$ repo sync

You can build any image, custom projects may need multiple builds for development, then imx-image-core is a great option since it's light and compiling it requires less time.

$ MACHINE=imx93-11x11-lpddr4x-evk DISTRO=fsl-imx-xwayland source imx-setup-release.sh -b i.MX93
$ bitbake imx-image-core

OE Connectivity Sanity Checker can cause issues if not configured, you can skip host connectivity tests.

Patches provided in this document are for testing purposes, they lack upstreaming status to Yocto Project as they simulate an early starter porting process, you can disable QA errors that interrupt bitbaking and turn them to warnings.

ERROR: do_patch: QA Issue: Missing Upstream-Status in patch
Please add according to https://docs.yoctoproject.org/contributor-guide/
ERROR: do_patch: Fatal QA errors were found, failing task.
ERROR: Task failed with exit code '1'

Make the following modification.

$ nano conf/local.conf

CONNECTIVITY_CHECK_URIS = ""
ERROR_QA:remove = "patch-status"
WARN_QA:append = " patch-status"

3. Add debug-console-relocation layer to Yocto environment build.

As said at the introduction, you are provided with the meta-layer zipped so you can just move it to your Yocto build directory.

# Feel free to change this path to your download path
$ cd ~
$ unzip meta-imx-console.zip
$ cp -r meta-imx-console ~/Yocto-BSP/sources
$ cd ~/Yocto-BSP/i.MX93
$ bitbake-layers add-layer meta-imx-console
$ bitbake-layers show-layers

You should be able to see the following output

layer                 path                                                                    priority
========================================================================================================
core                  /home/joseph/Yocto-Console/sources/poky/meta                 5
yocto                 /home/joseph/Yocto-Console/sources/poky/meta-poky            5
openembedded-layer    /home/joseph/Yocto-Console/sources/meta-openembedded/meta-oe  5
multimedia-layer      /home/joseph/Yocto-Console/sources/meta-openembedded/meta-multimedia  5
meta-python           /home/joseph/Yocto-Console/sources/meta-openembedded/meta-python  5
freescale-layer       /home/joseph/Yocto-Console/sources/meta-freescale            5
freescale-3rdparty    /home/joseph/Yocto-Console/sources/meta-freescale-3rdparty   4
freescale-distro      /home/joseph/Yocto-Console/sources/meta-freescale-distro     4
fsl-bsp-release       /home/joseph/Yocto-Console/sources/meta-imx/meta-imx-bsp     8
fsl-sdk-release       /home/joseph/Yocto-Console/sources/meta-imx/meta-imx-sdk     8
imx-machine-learning  /home/joseph/Yocto-Console/sources/meta-imx/meta-imx-ml      9
v2x-imx               /home/joseph/Yocto-Console/sources/meta-imx/meta-imx-v2x     9
imx-demo              /home/joseph/Yocto-Console/sources/meta-nxp-demo-experience  7
nxp-matter-baseline   /home/joseph/Yocto-Console/sources/meta-nxp-connectivity/meta-nxp-matter-baseline  7
nxp-openthread        /home/joseph/Yocto-Console/sources/meta-nxp-connectivity/meta-nxp-openthread  7
meta-arm              /home/joseph/Yocto-Console/sources/meta-arm/meta-arm         5
arm-toolchain         /home/joseph/Yocto-Console/sources/meta-arm/meta-arm-toolchain  5
clang-layer           /home/joseph/Yocto-Console/sources/meta-clang                7
gnome-layer           /home/joseph/Yocto-Console/sources/meta-openembedded/meta-gnome  5
networking-layer      /home/joseph/Yocto-Console/sources/meta-openembedded/meta-networking  5
filesystems-layer     /home/joseph/Yocto-Console/sources/meta-openembedded/meta-filesystems  5
perl-layer            /home/joseph/Yocto-Console/sources/meta-openembedded/meta-perl  5
qt6-layer             /home/joseph/Yocto-Console/sources/meta-qt6                  5
parsec-layer          /home/joseph/Yocto-Console/sources/meta-security/meta-parsec  5
tpm-layer             /home/joseph/Yocto-Console/sources/meta-security/meta-tpm    6
virtualization-layer  /home/joseph/Yocto-Console/sources/meta-virtualization       8
meta-freescale-ml     /home/joseph/Yocto-Console/sources/meta-freescale-ml         8
meta-imx-console      /home/joseph/Yocto-Console/sources/meta-imx-console          9

* Remember to run all steps within the Yocto session, otherwise source your setup again. *

$ cd Yocto-BSP
$ source imx-setup-release.sh -b i.MX93

4. Rebuild the core image.

Perform bitbake command again, it unpacks, patches, builds, deploys the source code and creates the root filesystem again with only running a few tasks.

NOTE: Tasks Summary: Attempted 11106 tasks of which 10941 didn't need to be rerun and all succeeded.

You can find the images for flashing under the build folder.

$ cd tmp/deploy/images/imx93-11x11-lpddr4x-evk/
$ zstd -d imx-image-core-imx93-11x11-lpddr4x-evk.rootfs-*.wic.zst
imx-image-core-imx93-11x11-lpddr4x-evk.rootfs-20260207040424.wic.zst: 2596424704 bytes

Flash the imx-boot firmware and imx-image-core root filesystem.

$ uuu -b emmc_all imx-boot-imx93-11x11-lpddr4x-evk-sd.bin-flash_singleboot imx-image-core-imx93-11x11-lpddr4x-evk.rootfs-*.wic

Conclusions.

You can open the consoles for Cortex-A and Cortex-M to experiment booting a normal image and the relocated LPUART image.

* This new image would require Cortex-M demos to change debug console to LPUART1. *

Debug console outputs through LPUART2 and prints a custom message.

Normal image debug console.

Remember that the patches below are provided as is, they were developed under LF-6.12.49. When using them you are subject to the record of acceptance and legal compliance from EULA agreement in your Yocto build. If applying them under other circumstances (another BSP repository, another Yocto version, etc.) or the same circumstances, and they fail, please create a support ticket to help you.

Extras.

If you compare the differences at patch-level, you can see that only a file was relocated in U-boot, the file containing the environment variables was renamed and the syntax changes a little.

The procedure performed was the same as the last article, if you are making your own layer, remember to modify conf/layer.conf with:

BBFILE_PRIORITY_meta-imx-console = "9"
#LAYERDEPENDS_meta-imx-console = "core"