scripts/mkimg.base: add efi loaders to the iso image

Strictly the 'efi' folder is not needed since it's in the efi.img.
However, converting .iso to USB stick is a lot simpler when the
EFI folder is in the .iso too. This allows just copying .iso contents
to the USB stick and EFI boot will work. While Rufus supports
extracting the boot files from efi.img, it was considered more
portable to add the copy. This also simplifies updating setup-bootable
to prepare EFI bootable disks.

scripts/mkimg.base.sh

@@ -165,28 +165,20 @@ grub_gen_earlyconf() {
 	EOF
 }
 
-build_grubefi_img() {
+build_grub_efi() {
 	local _format="$1"
 	local _efi="$2"
-	local _tmpdir="$WORKDIR/efiboot.$3"
-
-	# extra packages needed: grub-efi mtools
 
 	# Prepare grub-efi bootloader
-	mkdir -p "$_tmpdir/efi/boot"
-	grub_gen_earlyconf > "$_tmpdir"/grub_early.cfg
+	mkdir -p "$DESTDIR/efi/boot"
+	grub_gen_earlyconf > "$WORKDIR/grub_early.$3.cfg"
 	grub-mkimage \
-		--config="$_tmpdir"/grub_early.cfg \
+		--config="$WORKDIR/grub_early.$3.cfg" \
 		--prefix="/boot/grub" \
-		--output="$_tmpdir/efi/boot/$_efi" \
+		--output="$DESTDIR/efi/boot/$_efi" \
 		--format="$_format" \
 		--compression="xz" \
 		$grub_mod
-
-	# Create the EFI image
-	mkdir -p ${DESTDIR}/boot/grub/
-	mformat -i ${DESTDIR}/boot/grub/efi.img -C -f 1440 ::
-	mcopy -i ${DESTDIR}/boot/grub/efi.img -s $_tmpdir/efi ::
 }
 
 section_grubieee1275() {
@@ -197,7 +189,7 @@ section_grubieee1275() {
 	build_section grub_cfg boot/grub/grub.cfg $(grub_gen_config | checksum)
 }
 
-section_grubefi() {
+section_grub_efi() {
 	[ -n "$grub_mod" ] || return 0
 	[ "$output_format" = "iso" ] || return 0
 
@@ -217,7 +209,7 @@ section_grubefi() {
 	esac
 
 	build_section grub_cfg boot/grub/grub.cfg $(grub_gen_config | checksum)
-	build_section grubefi_img $_format $_efi $(grub_gen_earlyconf | checksum)
+	build_section grub_efi $_format $_efi $(grub_gen_earlyconf | checksum)
 }
 
 create_image_iso() {
@@ -236,8 +228,12 @@ create_image_iso() {
 			-boot-info-table
 			"
 	fi
-	if [ -e "${DESTDIR}/boot/grub/efi.img" ]; then
-		# efi boot enabled
+	if [ -e "${DESTDIR}/efi" -a -e "${DESTDIR}/boot/grub" ]; then
+		# Create the EFI boot partition image
+		mformat -i ${DESTDIR}/boot/grub/efi.img -C -f 1440 ::
+		mcopy -i ${DESTDIR}/boot/grub/efi.img -s ${DESTDIR}/efi ::
+
+		# Enable EFI boot
 		if [ -z "$_isolinux" ]; then
 			# efi boot only
 			_efiboot="