Below are the environment variables that can be set in the u-boot console to boot the Renesas Gen3 ULCB boards.

Adjust board type with the following identifiers:

* 'm3ulcb' for Renesas Gen3 Starter Kit Pro
* 'h3ulcb' for Renesas Gen3 Starter Kit Premium

################## Common options #####################
# these options are common to all configurations:

# choose board
setenv board m3ulcb
# or
setenv board h3ulcb

# kernel file
setenv set_bootkfile 'setenv bootkfile Image'
setenv bootkaddr 0x48080000

# dtb file
setenv set_bootdfile 'setenv bootdfile Image-r8a7796-${board}.dtb'
setenv bootdaddr 0x48000000

# initrd
setenv set_bootifile 'setenv bootifile initramfs-netboot-image-${board}.ext4.gz'
setenv bootiaddr 0x5C3F9520
setenv bootisize 3A6AB6

# kernel args
setenv bootargs_console 'console=ttySC0,115200 ignore_loglevel'
setenv bootargs_video 'vmalloc=384M video=HDMI-A-1:1920x1080-32@60'
setenv bootargs_extra 'rw rootfstype=ext4 rootwait rootdelay=2'

################ Boot on MMC (SDcard) #################

setenv bootargs_root 'root=/dev/mmcblk1p1'
setenv bootmmc '0:1'
setenv bootkload_sd 'ext4load mmc ${bootmmc} ${bootkaddr} boot/${bootkfile}'
setenv bootdload_sd 'ext4load mmc ${bootmmc} ${bootdaddr} boot/${bootdfile}'
setenv bootload_sd 'run set_bootkfile; run bootkload_sd; run set_bootdfile; run bootdload_sd'
setenv bootcmd 'setenv bootargs ${bootargs_console} ${bootargs_video} ${bootargs_root} ${bootargs_extra}; run bootload_sd; booti ${bootkaddr} - ${bootdaddr}'

################ Boot on MMC (SDcard) with initrd ######

setenv bootargs_root 'root=/dev/ram0 ramdisk_size=16384'
setenv bootmmc '0:1'
setenv bootkload_sd 'ext4load mmc ${bootmmc} ${bootkaddr} boot/${bootkfile}'
setenv bootdload_sd 'ext4load mmc ${bootmmc} ${bootdaddr} boot/${bootdfile}'
setenv bootiload_sd 'ext4load mmc ${bootmmc} ${bootiaddr} boot/${bootifile}'
setenv bootload_sd 'run set_bootkfile; run bootkload_sd; run set_bootdfile; run bootdload_sd; run set_bootifile; run bootiload_sd'

setenv bootcmd 'setenv bootargs ${bootargs_console} ${bootargs_video} ${bootargs_root} ${bootargs_extra}; run bootload_sd; booti ${bootkaddr} ${bootiaddr}:${bootisize} ${bootdaddr}'

################ Netboot through TFTP+NBD ##################
# replace <IP> addresses by appropriate addresses

setenv ipaddr '<board_IP>'
setenv serverip '<server_IP>'

setenv bootargs_root 'root=/dev/ram0 ramdisk_size=16384 ip=dhcp'
setenv bootkload_net 'tftp ${bootkaddr} ${board}/${bootkfile}'
setenv bootdload_net 'tftp ${bootdaddr} ${board}/${bootdfile}'
setenv bootiload_net 'tftp ${bootiaddr} ${board}/${bootifile}'
setenv bootload_net 'run set_bootkfile; run bootkload_net; run set_bootdfile; run bootdload_net; run set_bootifile; run bootiload_net'

setenv bootcmd 'setenv bootargs ${bootargs_console} ${bootargs_video} ${bootargs_root} ${bootargs_extra} nbd.server=${serverip}; run bootload_net; booti ${bootkaddr} ${bootiaddr}:${bootisize} ${bootdaddr}'