buildroot/board/embest/riotboard/genimage.cfg

image sdcard.img {
	hdimage {
	}

	partition u-boot {
		in-partition-table = "no"
		image = "u-boot.imx"
		offset = 1K
	}

	partition rootfs {
		partition-type = 0x83
		image = "rootfs.ext2"
		offset = 1M
		size = 60M
	}
}