Index: tools/tools/nanobsd/defaults.sh
===================================================================
--- tools/tools/nanobsd/defaults.sh
+++ tools/tools/nanobsd/defaults.sh
@@ -140,9 +140,12 @@
 # Can be "file" or "swap"
 NANO_MD_BACKING="file"
 
-# for swap type md(4) backing, write out the mbr only
+# For swap type md(4) backing, write out the mbr only
 NANO_IMAGE_MBRONLY=true
 
+# Partitioning scheme: MBR or GPT
+NANO_PART_SCHEME=MBR
+
 # Progress Print level
 PPLEVEL=3
 
@@ -419,7 +422,7 @@
 	echo "$NANO_RAM_TMPVARSIZE" > conf/base/var/md_size
 
 	# pick up config files from the special partition
-	echo "mount -o ro /dev/${NANO_DRIVE}s3" > conf/default/etc/remount
+	echo "mount -o ro /dev/${NANO_DRIVE}${SLICE}3" > conf/default/etc/remount
 
 	# Put /tmp on the /var ramdisk (could be symlink already)
 	nano_rm -rf tmp
@@ -443,8 +446,8 @@
 	# save config file for scripts
 	echo "NANO_DRIVE=${NANO_DRIVE}" > etc/nanobsd.conf
 
-	echo "/dev/${NANO_DRIVE}s1a / ufs ro 1 1" > etc/fstab
-	echo "/dev/${NANO_DRIVE}s3 /cfg ufs rw,noauto 2 2" >> etc/fstab
+	echo "/dev/${NANO_DRIVE}${SYS1_SLICE} / ufs ro 1 1" > etc/fstab
+	echo "/dev/${NANO_DRIVE}${SLICE}3 /cfg ufs rw,noauto 2 2" >> etc/fstab
 	mkdir -p cfg
 	)
 )
@@ -505,25 +508,37 @@
 	pprint 3 "log: ${NANO_OBJ}/_.di"
 
 	(
-	echo $NANO_MEDIASIZE $NANO_IMAGES \
+        case $NANO_PART_SCHEME in
+          	MBR)
+			unset GPART_LABEL
+			GPART_BOOTFL="active"
+			GPART_UFS="freebsd"
+			NANO_GPART_MEDIASIZE=${NANO_MEDIASIZE}
+			;;
+		GPT)
+			GPART_LABEL="-l ${NANO_LABEL}"
+			GPART_BOOTFL="bootme"
+			GPART_UFS="freebsd-ufs"
+			NANO_GPART_MEDIASIZE=$((${NANO_MEDIASIZE} - 256))
+			# Reserve 256 sectors for boot partition
+			;;
+	esac
+	echo $NANO_GPART_MEDIASIZE $NANO_IMAGES \
 		$NANO_SECTS $NANO_HEADS \
 		$NANO_CODESIZE $NANO_CONFSIZE $NANO_DATASIZE |
+        
 	awk '
 	{
 		printf "# %s\n", $0
 
+		print "create -s '$NANO_PART_SCHEME'"
+
 		# size of cylinder in sectors
 		cs = $3 * $4
 
 		# number of full cylinders on media
 		cyl = int ($1 / cs)
 
-		# output fdisk geometry spec, truncate cyls to 1023
-		if (cyl <= 1023)
-			print "g c" cyl " h" $4 " s" $3
-		else
-			print "g c" 1023 " h" $4 " s" $3
-
 		if ($7 > 0) { 
 			# size of data partition in full cylinders
 			dsl = int (($7 + cs - 1) / cs)
@@ -542,36 +557,35 @@
 		}
 
 		# First image partition start at second track
-		print "p 1 165 " $3, isl * cs - $3
+		print "add -t ${GPART_UFS} -b " $3 " -s " isl * cs - $3 " -i 1 ${GPART_LABEL+${GPART_LABEL}${SLICE}1}"
+		print "set -i 1 -a ${GPART_BOOTFL}"
 		c = isl * cs;
 
 		# Second image partition (if any) also starts offset one 
 		# track to keep them identical.
 		if ($2 > 1) {
-			print "p 2 165 " $3 + c, isl * cs - $3
+			print "add -t ${GPART_UFS} -b " $3 + c " -s " isl * cs - $3 " -i 2 ${GPART_LABEL+${GPART_LABEL}${SLICE}2}"
 			c += isl * cs;
 		}
 
 		# Config partition starts at cylinder boundary.
-		print "p 3 165 " c, csl * cs
+		print "add -t ${GPART_UFS} -b " c " -s " csl * cs " -i 3 ${GPART_LABEL+${GPART_LABEL}${SLICE}3}"
 		c += csl * cs
 
 		# Data partition (if any) starts at cylinder boundary.
 		if ($7 > 0) {
-			print "p 4 165 " c, dsl * cs
+			print "add -t ${GPART_UFS} -b " c " -s " dsl * cs " -i 4 ${GPART_LABEL+${GPART_LABEL}${SLICE}4}"
 		} else if ($7 < 0 && $1 > c) {
-			print "p 4 165 " c, $1 - c
+			print "add -t ${GPART_UFS} -b " c " -s " $1 - c " -i 4 ${GPART_LABEL+${GPART_LABEL}${SLICE}4}"
 		} else if ($1 < c) {
 			print "Disk space overcommitted by", \
 			    c - $1, "sectors" > "/dev/stderr"
 			exit 2
 		}
-
-		# Force slice 1 to be marked active. This is necessary
-		# for booting the image from a USB device to work.
-		print "a 1"
+		print "commit!"
+		print "show!"
 	}
-	' > ${NANO_OBJ}/_.fdisk
+	' | sed -e 's/^[^#]/gpart &/' -e 's/[^!]$/& -f x!/' -e 's/!$/ ${MD}/' > ${NANO_OBJ}/_.gpart
 
 	IMG=${NANO_DISKIMGDIR}/${NANO_IMGNAME}
 	MNT=${NANO_OBJ}/_.mnt
@@ -590,23 +604,39 @@
 
 	trap "echo 'Running exit trap code' ; df -i ${MNT} ; nano_umount ${MNT} || true ; mdconfig -d -u $MD" 1 2 15 EXIT
 
-	fdisk -i -f ${NANO_OBJ}/_.fdisk ${MD}
-	fdisk ${MD}
+	(set -x; . ${NANO_OBJ}/_.gpart)
 	# XXX: params
 	# XXX: pick up cached boot* files, they may not be in image anymore.
-	if [ -f ${NANO_WORLDDIR}/${NANO_BOOTLOADER} ]; then
-		boot0cfg -B -b ${NANO_WORLDDIR}/${NANO_BOOTLOADER} ${NANO_BOOT0CFG} ${MD}
-	fi
-	if [ -f ${NANO_WORLDDIR}/boot/boot ]; then
-		bsdlabel -w -B -b ${NANO_WORLDDIR}/boot/boot ${MD}s1
-	else
-		bsdlabel -w ${MD}s1
-	fi
-	bsdlabel ${MD}s1
+
+	case $NANO_PART_SCHEME in
+		MBR)
+			# For MBR, we need to create a disklabel in the system slice to hold the
+			# boot blocks.
+			if [ -f ${NANO_WORLDDIR}/${NANO_BOOTLOADER} ]; then
+				boot0cfg -B -b ${NANO_WORLDDIR}/${NANO_BOOTLOADER} ${NANO_BOOT0CFG} ${MD}
+			fi
+			if [ -f ${NANO_WORLDDIR}/boot/boot ]; then
+				bsdlabel -w -B -b ${NANO_WORLDDIR}/boot/boot ${MD}s1
+			else
+				bsdlabel -w ${MD}s1
+			fi
+			bsdlabel ${MD}s1
+			;;
+		GPT)
+			# For GPT, no bsdlabel is required, since the boot blocks live in their
+			# own freebsd-boot partition, and in any case gptboot expects freebsd-ufs
+			# partitions to contain an UFS filesystem, *not* a bsdlabel.
+			gpart add -t freebsd-boot -s 256 -i 15 ${GPART_LABEL}boot -f x ${MD}
+			if [ -f ${NANO_WORLDDIR}/boot/pmbr -a -f ${NANO_WORLDDIR}/boot/gptboot ]; then
+				gpart bootcode -b ${NANO_WORLDDIR}/boot/pmbr -p ${NANO_WORLDDIR}/boot/gptboot -i 15 -f x ${MD}
+			fi
+			gpart commit ${MD}
+			;;
+	esac
 
 	# Create first image
-	populate_slice /dev/${MD}s1a ${NANO_WORLDDIR} ${MNT} "s1a"
-	mount /dev/${MD}s1a ${MNT}
+	populate_slice /dev/${MD}${SYS1_SLICE} ${NANO_WORLDDIR} ${MNT} "${SYS1_SLICE}"
+	mount /dev/${MD}${SYS1_SLICE} ${MNT}
 	echo "Generating mtree..."
 	( cd ${MNT} && mtree -c ) > ${NANO_OBJ}/_.mtree
 	( cd ${MNT} && du -k ) > ${NANO_OBJ}/_.du
@@ -615,26 +645,26 @@
 	if [ $NANO_IMAGES -gt 1 -a $NANO_INIT_IMG2 -gt 0 ] ; then
 		# Duplicate to second image (if present)
 		echo "Duplicating to second image..."
-		dd conv=sparse if=/dev/${MD}s1 of=/dev/${MD}s2 bs=64k
-		mount /dev/${MD}s2a ${MNT}
+		dd conv=sparse if=/dev/${MD}${SLICE}1 of=/dev/${MD}${SLICE}2 bs=64k
+		mount /dev/${MD}${SYS2_SLICE} ${MNT}
 		for f in ${MNT}/etc/fstab ${MNT}/conf/base/etc/fstab
 		do
-			sed -i "" "s=${NANO_DRIVE}s1=${NANO_DRIVE}s2=g" $f
+			sed -i "" "s=${NANO_DRIVE}${SLICE}1=${NANO_DRIVE}${SLICE}2=g" $f
 		done
 		nano_umount ${MNT}
 		# Override the label from the first partition so we
 		# don't confuse glabel with duplicates.
 		if [ ! -z ${NANO_LABEL} ]; then
-			tunefs -L ${NANO_LABEL}"s2a" /dev/${MD}s2a
+			tunefs -L ${NANO_LABEL}"${SYS2_SLICE}" /dev/${MD}${SYS2_SLICE}
 		fi
 	fi
 	
 	# Create Config slice
-	populate_cfg_slice /dev/${MD}s3 "${NANO_CFGDIR}" ${MNT} "s3"
+	populate_cfg_slice /dev/${MD}${SLICE}3 "${NANO_CFGDIR}" ${MNT} "${SLICE}3"
 
 	# Create Data slice, if any.
 	if [ $NANO_DATASIZE -ne 0 ] ; then
-		populate_data_slice /dev/${MD}s4 "${NANO_DATADIR}" ${MNT} "s4"
+		populate_data_slice /dev/${MD}${SLICE}4 "${NANO_DATADIR}" ${MNT} "${SLICE}4"
 	fi
 
 	if [ "${NANO_MD_BACKING}" = "swap" ] ; then
@@ -652,7 +682,7 @@
 
 	if ${do_copyout_partition} ; then
 		echo "Writing out _.disk.image..."
-		dd conv=sparse if=/dev/${MD}s1 of=${NANO_DISKIMGDIR}/_.disk.image bs=64k
+		dd conv=sparse if=/dev/${MD}${SLICE}1 of=${NANO_DISKIMGDIR}/_.disk.image bs=64k
 	fi
 	mdconfig -d -u $MD
 
@@ -948,6 +978,20 @@
 	# Override user's NANO_DRIVE if they specified a NANO_LABEL
 	[ ! -z "${NANO_LABEL}" ] && NANO_DRIVE="ufs/${NANO_LABEL}"
 
+	# Set SLICE prefix character according to partitioning scheme
+	case ${NANO_PART_SCHEME} in
+	MBR)
+		SLICE=s
+		SYS1_SLICE=${SLICE}1a
+		SYS2_SLICE=${SLICE}2a
+		;;
+	GPT)
+		SLICE=p
+		SYS1_SLICE=${SLICE}1
+		SYS2_SLICE=${SLICE}2
+		;;
+	esac
+
 	# Set a default NANO_TOOLS to NANO_SRC/NANO_TOOLS if it exists.
 	[ ! -d "${NANO_TOOLS}" ] && [ -d "${NANO_SRC}/${NANO_TOOLS}" ] && \
 		NANO_TOOLS="${NANO_SRC}/${NANO_TOOLS}"