buildroot/board/stmicroelectronics/common/stm32mp157/genimage.cfg

image sdcard.img {
	hdimage {
		gpt = "true"
	}

	partition fsbl1 {
		image = "u-boot-spl.stm32"
	}

	partition fsbl2 {
		image = "u-boot-spl.stm32"
	}

	partition ssbl {
		image = "u-boot.img"
	}

	partition rootfs {
		image = "rootfs.ext4"
		partition-type = 0x83
		bootable = "yes"
	}
}