--- DistUpgradeQuirks.py.orig	2014-03-05 09:55:23.128905859 +0700
+++ DistUpgradeQuirks.py	2014-03-05 10:12:04.596902543 +0700
@@ -148,6 +148,7 @@
         self._test_and_warn_on_i8xx()
 
     def from_precisePostInitialUpdate(self):
+        self._checkPae()
         self._test_and_warn_for_unity_3d_support()
 
     def oneiricPostInitialUpdate(self):
@@ -478,6 +479,27 @@
         except Exception as e:
             logging.warning("error during unlink of old crash files (%s)" % e)
 
+    def _checkPae(self):
+        " check PAE in /proc/cpuinfo"
+        # upgrade from Precise will fail if PAE is not in cpu flags
+        logging.debug("_checkPae")
+        pae = 0
+        f = open('/proc/cpuinfo', 'r')
+        for s in f:
+            if re.match(r'^\s*flags\s*:.*pae', s):
+                pae = 1
+        f.close()
+        if not pae:
+            logging.error("no pae in /proc/cpuinfo")
+            summary = _("PAE not enabled")
+            msg = _("Your system uses a CPU that does not have PAE enabled. "
+                    "Ubuntu only supports non-PAE systems up to Ubuntu "
+                    "12.04. To upgrade to a later version of Ubuntu, you "
+                    "must enable PAE (if this is possible) - see "
+                    "http://help.ubuntu.com/community/EnablingPAE")
+            self._view.error(summary, msg)
+            self.controller.abort()
+
     def _checkVideoDriver(self, name):
         " check if the given driver is in use in xorg.conf "
         XORG = "/etc/X11/xorg.conf"