PartitionTable: Initial GPT Support, Adding Block Limit

Also added a script to handle creation of GPT partitioned disk (with
GRUB config file). Block limit will be used to disallow potential access
to other partitions.

Kernel/build-gpt-image-grub.sh

@@ -0,0 +1,87 @@
+#!/bin/bash
+
+set -e
+
+die() {
+    echo "die: $@"
+    exit 1
+}
+
+if [ $(id -u) != 0 ]; then
+    die "this script needs to run as root"
+fi
+
+grub=$(which grub-install 2>/dev/null) || true
+if [[ -z "$grub" ]]; then
+    grub=$(which grub2-install 2>/dev/null) || true
+fi
+if [ -z "$grub" ]; then
+    echo "can't find a grub-install or grub2-install binary, oh no"
+    exit 1
+fi
+echo "using grub-install at ${grub}"
+
+echo "setting up disk image..."
+dd if=/dev/zero of=_disk_image bs=1M count=${DISK_SIZE:-701} status=none || die "couldn't create disk image"
+chown 1000:1000 _disk_image || die "couldn't adjust permissions on disk image"
+echo "done"
+
+echo -n "creating loopback device... "
+dev=$(losetup --find --partscan --show _disk_image)
+if [ -z $dev ]; then
+    die "couldn't mount loopback device"
+fi
+echo "loopback device is at ${dev}"
+
+cleanup() {
+    if [ -d mnt ]; then
+        echo -n "unmounting filesystem... "
+        umount mnt || ( sleep 1 && sync && umount mnt )
+        rm -rf mnt
+        echo "done"
+    fi
+
+    if [ -e ${dev} ]; then
+        echo -n "cleaning up loopback device... "
+        losetup -d ${dev}
+        echo "done"
+    fi
+}
+trap cleanup EXIT
+
+echo -n "creating partition table... "
+parted -s ${dev} mklabel gpt mkpart BIOSBOOT ext3 1MiB 8MiB mkpart OS ext2 8MiB 700MiB set 1 bios_grub || die "couldn't partition disk"
+echo "done"
+
+echo -n "destroying old filesystem... "
+dd if=/dev/zero of=${dev}p2 bs=1M count=1 status=none || die "couldn't destroy old filesystem"
+echo "done"
+
+echo -n "creating new filesystem... "
+mke2fs -q ${dev}p2 || die "couldn't create filesystem"
+echo "done"
+
+echo -n "mounting filesystem... "
+mkdir -p mnt
+mount ${dev}p2 mnt/ || die "couldn't mount filesystem"
+echo "done"
+
+./build-root-filesystem.sh
+
+echo -n "creating /boot... "
+mkdir -p mnt/boot
+echo "done"
+
+echo "installing grub using $grub..."
+$grub --boot-directory=mnt/boot --target=i386-pc --modules="ext2 part_msdos part_gpt" ${dev}
+
+if [ -d mnt/boot/grub2 ]; then
+    cp grub_gpt.cfg mnt/boot/grub2/grub.cfg
+else
+    cp grub_gpt.cfg mnt/boot/grub/grub.cfg
+fi
+echo "done"
+
+echo -n "installing kernel in /boot... "
+cp kernel mnt/boot
+echo "done"