Make move_disk work on bare metal

* Use -S32 -H64 --force to trick sfdisk into allowing MiB-aligned
  partitions on a drive that reports a CHS geometry
* Explicitly create partition at sector 2097152 (=1GiB)
* Force mkfs.ext4 to overwrite any existing filesystem it might find
* Wait up to 2 minutes for the disk to become readable (especially
  USB drives often show up with a delay)

steps/jump/move_disk.sh

@@ -10,13 +10,25 @@ mkdir -p /dev /etc
 mount -t devtmpfs none /dev &> /junk || true # no /dev/null yet
 rm /junk &> /dev/null || true
 
+timeout=120
+while ! dd if=/dev/${DISK} of=/dev/null bs=512 count=1; do
+    sleep 1
+    # shellcheck disable=SC2219
+    let timeout--
+    if [ "${timeout}" -le 0 ]; then
+        echo "Timeout reached for disk to become accessible"
+        false
+    fi
+done
+
 # Create partition if it doesn't exist
 if [ $(($(stat -c "%Lr" "/dev/${DISK}") % 8)) -eq 0 ]; then
     echo "Creating partition table..."
-    echo ";" | sfdisk "/dev/${DISK}"
+    # Start at 1GiB, use -S32 -H64 to align to MiB rather than cylinder boundary
+    echo "2097152;" | sfdisk -uS -S32 -H64 --force "/dev/${DISK}"
     fdisk -l "/dev/${DISK}"
     echo "Creating ext4 partition..."
-    mkfs.ext4 "/dev/${DISK}1"
+    mkfs.ext4 -F -F "/dev/${DISK}1"
     DISK="${DISK}1"
 fi