I’m trying to make a raspberry-pi CM4 work with u-boot and an ext4 boot partition instead of the regular vfat. This is necessary for an OTA update to happen also for the boot partition with a tool called RAUC.

QUESTION: What is the advised u-boot script to handle the ext4 boot partition?

The minimal viable example of boot.scr for a running vfat partition is as below:

fdt addr ${fdt_addr} && fdt get value bootargs /chosen bootargs

fatload mmc 0:1 ${kernel_addr_r} @@KERNEL_IMAGETYPE@@
if test ! -e mmc 0:1 uboot.env; then saveenv; fi;
@@KERNEL_BOOTCMD@@ ${kernel_addr_r} - ${fdt_addr}

The boot partition is the first one on the image, created with wic tool. I’ve found out that ext4load command should make it possible to load things from the ext4 /boot, however swapping fatload to ext4load does not work. The board does not boot.
The other thing enabled are kernel config options CONFIG_CMD_EXT4 and CONFIG_CMD_EXT4_WRITE.