board/pine64/rock64/genimage.cfg

image sdcard.img {
    hdimage {
    }

    partition uboot-spl {
        in-partition-table = "no"
        image = "u-boot-tpl-spl.img"
        offset = 32768 # 512 * 0x40 from start of sd card
    }

    partition uboot {
        in-partition-table = "no"
        image = "u-boot.itb"
        offset = 262144 # 512 * 0x200 from start of sd card
    }

    partition rootfs {
        partition-type = 0x83
        bootable = "yes"
        image = "rootfs.ext2"
        size = 500M
    }
}