Add support for UEFI

.github/workflows/ci.yml

@@ -38,3 +38,16 @@ jobs:
               --fs-skel-chown root:root \
               --script-chroot \
               alpine2-$(date +%Y-%m-%d).qcow2 -- ./example/configure.sh
+
+      - name: Build image with UEFI boot mode
+        run: |
+          sudo ./alpine-make-vm-image \
+              --image-format qcow2 \
+              --image-size 2G \
+              --boot-mode UEFI \
+              --repositories-file example/repositories \
+              --packages "$(cat example/packages)" \
+              --fs-skel-dir example/rootfs \
+              --fs-skel-chown root:root \
+              --script-chroot \
+              alpine2-$(date +%Y-%m-%d).qcow2 -- ./example/configure.sh

README.adoc

@@ -9,7 +9,8 @@ image:https://github.com/{gh-name}/workflows/CI/badge.svg["Build Status", link="
 endif::env-github[]
 
 This project provides a script for making customized https://alpinelinux.org/[Alpine Linux] disk images for virtual machines.
-It’s quite simple (300 LoC of shell), fast (~32 seconds on GitHub Actions) and requires minimum dependencies (QEMU and filesystem tools).
+You can choose between BIOS mode (using https://syslinux.org/[Syslinux]) and UEFI mode (using Linux https://docs.kernel.org/admin-guide/efi-stub.html[EFI stub]).
+It’s quite simple (400 LoC of shell), fast (~32 seconds on GitHub Actions), requires minimum dependencies (QEMU and filesystem tools).
 
 TIP: Don’t need VM, just wanna chroot into Alpine Linux?
      Try https://github.com/alpinelinux/alpine-chroot-install[alpine-chroot-install]!
@@ -23,9 +24,10 @@ TIP: Don’t need VM, just wanna chroot into Alpine Linux?
 * POSIX-sh compatible shell (e.g. Busybox ash, dash, Bash, ZSH)
 * qemu-img and qemu-nbd
 * rsync (needed only for `--fs-skel-dir`)
-* sfdisk (needed only for `--partition`)
-* mdev or udevadm (needed only for `--partition` when device hotplug doesn’t work)
+* sfdisk (needed only for `--partition` and `--boot-mode UEFI`)
+* mdev or udevadm (needed only for `--partition` and `--boot-mode UEFI` if device hotplug doesn’t work)
 * e2fsprogs (for ext4), btrfs-progs (for Btrfs), or xfsprogs (for XFS)
+* dosfstools (needed only for `--boot-mode UEFI`)
 
 All dependencies except the first two are automatically installed by the script when running on Alpine.
 

alpine-make-vm-image

@@ -25,6 +25,8 @@
 #   <script-opts>                         Arguments to pass to the script.
 #
 # Options and Environment Variables:
+#   -B --boot-mode BOOT_MODE              Either "BIOS" (default) or "UEFI".
+#
 #   -b --branch ALPINE_BRANCH             Alpine branch to install; used only when
 #                                         --repositories-file is not specified. Default is
 #                                         latest-stable.
@@ -36,6 +38,7 @@
 #                                         specified USER:GROUP.
 #
 #   -P --partition (PARTITION)            Create GUID Partition Table (GPT) with a single partition.
+#                                         GPT is always created for --boot-mode UEFI.
 #
 #   -f --image-format IMAGE_FORMAT        Format of the disk image (see qemu-img --help).
 #
@@ -189,6 +192,27 @@ blk_uuid() {
 	blkid "$dev" | sed -En 's/.*\bUUID="([^"]+)".*/\1/p'
 }
 
+# Creates GPT parition table on the device $1 for boot mode $2 (BIOS or UEFI).
+create_gpt() {
+	local dev="$1"
+	local mode="$2"
+
+	case "$mode" in
+		BIOS) printf '%s\n' \
+			'label: gpt' \
+			'name=system,type=L,bootable,attrs=LegacyBIOSBootable' \
+			| sfdisk "$dev"
+		;;
+		UEFI) printf '%s\n' \
+			'label: gpt' \
+			'name=efi,type=U,size=128M,bootable' \
+			'name=system,type=L' \
+			| sfdisk "$nbd_dev"
+		;;
+		*) die "Invalid mode: $mode";;
+	esac
+}
+
 # Writes Alpine APK keys embedded in this script into directory $1.
 dump_alpine_keys() {
 	local dest_dir="$1"
@@ -221,6 +245,7 @@ fs_progs_pkg() {
 	case "$fs" in
 		ext4) echo 'e2fsprogs';;
 		btrfs) echo 'btrfs-progs';;
+		vfat) echo 'dosfstools';;
 		xfs) echo 'xfsprogs';;
 	esac
 }
@@ -350,14 +375,15 @@ wgets() (
 
 #=============================  M a i n  ==============================#
 
-opts=$(getopt -n $PROGNAME -o b:cCf:hi:k:m:p:Pr:s:S:tv \
-	-l branch:,fs-skel-chown:,fs-skel-dir:,image-format:,image-size:,initfs-features:,kernel-flavor:,keys-dir:,mirror-uri:,no-cleanup,packages:,partition,repositories-file:,rootfs:,script-chroot,serial-console,help,version \
+opts=$(getopt -n $PROGNAME -o b:B:cCf:hi:k:m:p:Pr:s:S:tv \
+	-l boot-mode:,branch:,fs-skel-chown:,fs-skel-dir:,image-format:,image-size:,initfs-features:,kernel-flavor:,keys-dir:,mirror-uri:,no-cleanup,packages:,partition,repositories-file:,rootfs:,script-chroot,serial-console,help,version \
 	-- "$@") || help 1 >&2
 
 eval set -- "$opts"
 while [ $# -gt 0 ]; do
 	n=2
 	case "$1" in
+		-B | --boot-mode) BOOT_MODE="$2";;
 		-b | --branch) ALPINE_BRANCH="$2";;
 		-S | --fs-skel-dir) FS_SKEL_DIR="$(realpath "$2")";;
 		     --fs-skel-chown) FS_SKEL_CHOWN="$2";;
@@ -383,6 +409,7 @@ done
 
 : ${ALPINE_BRANCH:="latest-stable"}
 : ${ALPINE_MIRROR:="http://dl-cdn.alpinelinux.org/alpine"}
+: ${BOOT_MODE:="BIOS"}
 : ${CLEANUP:="yes"}
 : ${FS_SKEL_CHOWN:=}
 : ${FS_SKEL_DIR:=}
@@ -402,6 +429,12 @@ case "$ALPINE_BRANCH" in
 	[0-9]*) ALPINE_BRANCH="v$ALPINE_BRANCH";;
 esac
 
+case "$BOOT_MODE" in
+	BIOS | bios) BOOT_MODE='BIOS';;
+	UEFI | uefi) BOOT_MODE='UEFI';;
+	*) die "Invalid boot-mode: $BOOT_MODE";;
+esac
+
 if [ -f /etc/alpine-release ]; then
 	: ${INSTALL_HOST_PKGS:="yes"}
 else
@@ -428,7 +461,9 @@ if [ "$INSTALL_HOST_PKGS" = yes ]; then
 	if ! grep -q -w "$ROOTFS" /proc/filesystems; then
 		modprobe $ROOTFS
 	fi
-	_apk add -t $VIRTUAL_PKG qemu-img $(fs_progs_pkg "$ROOTFS") rsync sfdisk
+
+	[ "$BOOT_MODE" = 'UEFI' ] && vfatpkg="$(fs_progs_pkg 'vfat')" || vfatpkg=
+	_apk add -t $VIRTUAL_PKG qemu-img $(fs_progs_pkg "$ROOTFS") $vfatpkg rsync sfdisk
 fi
 
 #-----------------------------------------------------------------------
@@ -455,20 +490,30 @@ nbd_dev=$(attach_image "$IMAGE_FILE" "$IMAGE_FORMAT")
 
 
 #-----------------------------------------------------------------------
-if [ "$PARTITION" = yes ]; then
+if [ "$PARTITION" = yes ] || [ "$BOOT_MODE" = 'UEFI' ]; then
 	einfo 'Creating GPT partition table'
 
-	printf '%s\n' \
-		'label: gpt' \
-		'name=system,type=L,bootable,attrs=LegacyBIOSBootable' \
-		| sfdisk "$nbd_dev"
-	root_dev="${nbd_dev}p1"
+	create_gpt "$nbd_dev" "$BOOT_MODE"
+
+	if [ "$BOOT_MODE" = 'BIOS' ]; then
+		root_dev="${nbd_dev}p1"
+	else
+		esp_dev="${nbd_dev}p1"
+		root_dev="${nbd_dev}p2"
+	fi
 	# This is needed when running in a container.
 	settle_dev_node "$root_dev" || die "system didn't create $root_dev node"
 else
 	root_dev="$nbd_dev"
 fi
 
+#-----------------------------------------------------------------------
+if [ "$BOOT_MODE" = 'UEFI' ]; then
+	einfo 'Formatting EFI system partition'
+
+	mkfs.fat -F32 -n EFI "$esp_dev"
+fi
+
 #-----------------------------------------------------------------------
 einfo "Formatting image to $ROOTFS"
 
@@ -487,6 +532,11 @@ einfo "Mounting image at $mount_dir"
 
 mount "$root_dev" "$mount_dir"
 
+if [ "$BOOT_MODE" = 'UEFI' ]; then
+	install -d -m 000 "$mount_dir"/boot
+	mount -t vfat "$esp_dev" "$mount_dir"/boot
+fi
+
 #-----------------------------------------------------------------------
 einfo 'Installing base system'
 
@@ -532,23 +582,39 @@ else
 fi
 
 #-----------------------------------------------------------------------
-einfo 'Setting up extlinux bootloader'
+if [ "$BOOT_MODE" = 'BIOS' ]; then
+	einfo 'Setting up extlinux bootloader'
 
-_apk add --root . --no-scripts syslinux
-setup_extlinux . "UUID=$root_uuid" "$ROOTFS" "$KERNEL_FLAVOR" "$SERIAL_PORT"
+	_apk add --root . --no-scripts syslinux
+	setup_extlinux . "UUID=$root_uuid" "$ROOTFS" "$KERNEL_FLAVOR" "$SERIAL_PORT"
 
-if [ "$PARTITION" = yes ]; then
-	dd bs=440 count=1 conv=notrunc if=usr/share/syslinux/gptmbr.bin of="$nbd_dev"
-	sync
+	if [ "$PARTITION" = yes ]; then
+		dd bs=440 count=1 conv=notrunc if=usr/share/syslinux/gptmbr.bin of="$nbd_dev"
+		sync
+	fi
 fi
 
+#-----------------------------------------------------------------------
+einfo 'Configuring system'
+
 cat > etc/fstab <<-EOF
 	# <fs>		<mountpoint>	<type>	<opts>		<dump/pass>
 	UUID=$root_uuid	/		$ROOTFS	relatime	0 1
 EOF
 
-#-----------------------------------------------------------------------
-einfo 'Configuring system'
+if [ "$BOOT_MODE" = 'UEFI' ]; then
+	echo "LABEL=EFI	/boot		vfat\
+	rw,relatime,fmask=0022,codepage=437,iocharset=ascii,shortname=mixed,utf8,errors=remount-ro	0 2" \
+	>> etc/fstab
+
+	# This script is interpreted by UEFI.
+	echo "vmlinuz-$KERNEL_FLAVOR" \
+		"initrd=initramfs-$KERNEL_FLAVOR" \
+		"root=UUID=$root_uuid" \
+		"rootfstype=$ROOTFS" \
+		${SERIAL_PORT:+"console=ttyS0"} \
+		> boot/startup.nsh
+fi
 
 # We just prepare this config, but don't start the networking service.
 cat > etc/network/interfaces <<-EOF