MCIMX6UL-EVKB is a i.MX 6UltraLite Evaluation Kit.
It uses the NXP i.MX 6ULL (900 MHz Arm Cortex®-A7 core, MCIMX6Y2DVM09AB).
Instructions based on the porting guide – https://www.nxp.com/docs/en/user-guide/IMX_PORTING_GUIDE.pdf
Your eval board boots, but it hangs during the “starting linux kernel” message. You can’t debug the Linux kernel because it hasn’t loaded yet. So the next option is to debug the preceding U-Boot bootloader. This article explains how to configure a Yocto layer to modify the Uboot Kconfig settings (without hacking about in the tmp/work directory!)
As a simple example we will increase the auto boot delay – CONFIG_BOOTDELAY – from 3 seconds to 7 seconds.
Page Contents
- Install Yocto
- Build image-core-minimal for MACHINE= imx6ull14x14evk and DISTRO= fsl-imx-fb.
- Create custom layer called meta-custom-uboot.
- Copy existing machine file from meta-freescale layer
- Find U-Boot recipe file in meta-freescale layer
- Create bbappend file to override the recipe (for all versions)
- Add configuration fragment path to bbappend override file
- Create config fragment file
- Add Kconfig options to config fragment file
- Open local configuration file for the build
- Add new machine “custom_imx6ullevk” as preferred virtual bootloader provider for “u-boot-imx” recipe:
- The finished layer directory structure
- Rebuild the image for the new machine:
- Verify KConfig option is included in “u-boot-imx” build:
- Deploy image to build via sd card:
Install Yocto
See section 4, “Yocto Project Setup”, here –
https://www.nxp.com/docs/en/user-guide/IMX_YOCTO_PROJECT_USERS_GUIDE.pdf
Build image-core-minimal for MACHINE= imx6ull14x14evk and DISTRO= fsl-imx-fb.
DISTRO=<distro name> MACHINE=<machine name> source imx-setup-release.sh -b <build dir>
bitbake core-image-minimal
Create custom layer called meta-custom-uboot.
bitbake-layers create-layer ../sources/meta-custom-uboot
bitbake-layers add-layer ../sources/meta-custom-uboot
Copy existing machine file from meta-freescale layer
from
build/sources/meta-freescale/conf/machine/imx6ullevk.conf
to
build/sources/meta-custom-uboot/conf/machine/custom_imx6ullevk.conf
Find U-Boot recipe file in meta-freescale layer
build/sources/meta-freescale/recipes-bsp/u-boot/u-boot-imx_2020.04.bb
Create bbappend file to override the recipe (for all versions)
build/sources/meta-custom-uboot/recipes-bsp/u-boot/u-boot-imx_%.bbappend
Add configuration fragment path to bbappend override file
FILESEXTRAPATHS_prepend := "{THISDIR}/{PN}:"
SRC_URI += "file://myboot.cfg"
Create config fragment file
build/sources/meta-custom-uboot/recipes-bsp/u-boot/u-boot-imx/myboot.cfg
Add Kconfig options to config fragment file
CONFIG_BOOTDELAY=7
Open local configuration file for the build
build/conf/local.conf
Add new machine “custom_imx6ullevk” as preferred virtual bootloader provider for “u-boot-imx” recipe:
PREFERRED_PROVIDER_virtual/bootloader_custom_imx6ullevk = "u-boot-imx"
The finished layer directory structure
build/sources/meta-custom-uboot/
├── conf
│ ├── layer.conf
│ └── machine
│ └── custom_imx6ullevk.conf
├── COPYING.MIT
├── README
└── recipes-bsp
└── u-boot
├── u-boot-imx
│ └── myboot.cfg
└── u-boot-imx_%.bbappend
Rebuild the image for the new machine:
MACHINE=custom_imx6ullevk bitbake core-image-minimal
Verify KConfig option is included in “u-boot-imx” build:
cat tmp/work/custom_imx6ullevk-poky-linux-gnueabi/u-boot-imx/1_2021.04-r0/deploy-u-boot-imx/u-boot-imx-initial-env-custom_imx6ullevk-sd-2021.04-r0
Deploy image to build via sd card:
bzcat tmp/deploy/images/custom_imx6ullevk/core-image-minimal-custom_imx6ullevk.wic.bz2 | sudo dd of=/dev/mmcblk0 bs=1M status=progress conv=fsync