buildroot/board/khadas/vim3/genimage.cfg

image boot.vfat {
	vfat {
		files = {
			"Image",
			"meson-g12b-a311d-khadas-vim3.dtb",
			"extlinux"
		}

		label = "boot"
	}

	size = 64M
}

image sdcard.img {
	hdimage {
	}

	partition boot {
		partition-type = 0xC
		bootable = "true"
		image="boot.vfat"
		size = 64M
		offset = 2M
	}

	partition rootfs {
		partition-type = 0x83
		image = "rootfs.ext2"
		size = 128M
		offset = 0
	}
}