sl/mnt OK, lukas.

# MMC boot command
bootcmd_mmc=load mmc 0:1 ${loadaddr} kernel.itb; bootm

# Network boot command and vars
bootcmd_net=dhcp; tftpboot ${loadaddr} kernel.itb; bootm
autoload=no
serverip=192.168.0.1

# U-Boot will run this after loading this file
bootcmd_txt=run bootcmd_mmc

# Kernel cmdline
bootargs=cma=256M console=ttyS1,115200 root=/dev/mmcblk0p3 rootflags=subvol=root
rw rootwait