initial buildroot for linux 5.15

board/sifive/hifive-unleashed/genimage_sdcard.cfg

@@ -0,0 +1,23 @@
+image sdcard.img {
+	hdimage {
+		gpt = true
+	}
+
+	partition u-boot-spl {
+		image = "u-boot-spl.bin"
+		offset = 17K
+		partition-type-uuid = 5B193300-FC78-40CD-8002-E86C45580B47
+	}
+
+	partition u-boot {
+		image = "u-boot.itb"
+		offset = 1041K
+		partition-type-uuid = 2E54B353-1271-4842-806F-E436D6AF6985
+	}
+
+	partition rootfs {
+		image = "rootfs.ext4"
+		partition-type-uuid = 0FC63DAF-8483-4772-8E79-3D69D8477DE4
+		bootable = true
+	}
+}