Phytec i.MX 93 - Page 46

i.MX 93 BSP Manual PD24.1.1 Documentation Rev.: imx8mp-pd22.1.2-51-ga548be7d
(continued from previous page)
imx93-phycore-rpmsg.dtbo
imx93-phycore-no-emmc.dtbo
imx93-phycore-no-eth.dtbo
Available overlays for phyboard-nash-imx93-1.conf are:
imx93-phyboard-nash-peb-av-010.dtbo
imx93-phycore-rpmsg.dtbo
imx93-phycore-no-emmc.dtbo
imx93-phycore-no-eth.dtbo
The usage of overlays can be congured during runtime in Linux or U-Boot. Overlays are applied during
the boot process in the bootloader after the boot command is called and before the kernel is loaded. The
next sections explain the conguration in more detail.
Set ${overlays} variable
The ${overlays} U-Boot environment variable contains a space-separated list of overlays that will be applied
during boot. Depending on the boot source the overlays have to either be placed in the boot partition of
eMMC/SD-Card or are loaded over tftp. Overlays set in the $KERNEL_DEVICETREE Yocto machine
variable will be automatically added to the boot partition of the nal WIC image.
The ${overlays} variable can be either set directly in the U-Boot environment or can be part of the external
bootenv.txt environment le. By default, the ${overlays} variable comes from the external bootenv.txt
environment le which is located in the boot partition. You can read and write the le on booted target
from linux:
target:~$ cat /boot/bootenv.txt
overlays=imx93-phyboard-segin-peb-eval-01.dtbo imx93-phyboard-segin-peb-av-02.dtbo
Note
Make sure the boot partition is mounted! If it is not you can mount it with:
target:~$ mount /dev/mmcblkXp0 /boot
Changes will take eect after the next reboot. If no bootenv.txt le is available the overlays variable can be
set directly in the U-Boot environment.
u-boot=> setenv overlays imx93-phyboard-segin-peb-av-02.dtbo
u-boot=> printenv overlays
overlays=imx93-phyboard-segin-peb-av-02.dtbo
u-boot=> boot
If a user dened ${overlays} variable should be directly loaded from U-Boot environment but there is still
an external bootenv.txt available, the ${no_bootenv} variable needs to be set as a ag:
u-boot=> setenv no_bootenv 1
u-boot=> setenv overlays imx93-phyboard-segin-peb-av-02.dtbo
u-boot=> boot
More information about the external environment can be found in U-boot External Environment subsection
of the device tree overlay section.
Device Tree (DT) 42