bootable: u-boot: handle UBOOT_KERNEL_DTB being unset better

- require it for boot.scr scenario
- allow it for extlinux.conf, setup fdtdir
- better extlinux LABEL

Signed-off-by: Ricardo Pardini <[email protected]>

Author: rpardini

bash/bootable/armbian-u-boot.sh

@@ -188,6 +188,13 @@ function write_uboot_script() {
 	declare fat32_root_dir="${1}"
 	declare boot_cmd_file="${fat32_root_dir}/boot.cmd"
 
+	# It is absolutely unlikely that a (vendor/legacy) boot script will be used with a board that has fdtfile preset correctly.
+	# Thus check UBOOT_KERNEL_DTB is set, or bomb.
+	if [[ -z "${UBOOT_KERNEL_DTB}" ]]; then
+		log error "UBOOT_KERNEL_DTB is unset -- vendor/boot.scr requires a DTB to be set"
+		exit 2
+	fi
+
 	declare console_extra_args="${bootable_info['CONSOLE_EXTRA_ARGS']:-""}"
 	cat <<- BOOT_CMD > "${boot_cmd_file}"
 		# Hook u-boot bootscript; mkimage -C none -A arm -T script -d /boot.cmd /boot.scr
@@ -233,14 +240,25 @@ function write_uboot_extlinux() {
 	mkdir -p "${fat32_root_dir}/extlinux"
 	declare extlinux_conf="${fat32_root_dir}/extlinux/extlinux.conf"
 	cat <<- EXTLINUX_CONF > "${extlinux_conf}"
-		DEFAULT hook
-		LABEL hook
+		DEFAULT Tinkerbell Hook ${BOARD} ${BRANCH}
+		LABEL Tinkerbell Hook ${BOARD} ${BRANCH}
 			linux /vmlinuz
 			initrd /initramfs
 			append ${bootargs} ${tinkerbell_args}
-			fdt /dtb/${UBOOT_KERNEL_DTB}
 	EXTLINUX_CONF
-	# @TODO: fdtdir when UBOOT_KERNEL_DTB is unset
+
+	# If UBOOT_KERNEL_DTB is not set, just pass the fdtdir
+	if [[ -z "${UBOOT_KERNEL_DTB}" ]]; then
+		log info "UBOOT_KERNEL_DTB is unset; using fdtdir instead"
+		cat <<- EXTLINUX_CONF_FDTDIR >> "${extlinux_conf}"
+			fdtdir /dtb/
+		EXTLINUX_CONF_FDTDIR
+	else
+		log info "UBOOT_KERNEL_DTB is set (${UBOOT_KERNEL_DTB}); using it in extlinux.conf"
+		cat <<- EXTLINUX_CONF_DTB >> "${extlinux_conf}"
+			fdt /dtb/${UBOOT_KERNEL_DTB}
+		EXTLINUX_CONF_DTB
+	fi
 
 	log_file_bat "${extlinux_conf}" "info" "Produced Armbian u-boot extlinux.conf"