+dnl ** Booting from unregisterised .hc files?
+dnl --------------------------------------------------------------
+AC_ARG_ENABLE(hc-boot-unregisterised,
+[ --enable-hc-boot-unregisterised
+ With --enable-hc-boot, treat the intermediate .hc files as
+ unregisterised rather than registerised code.
+ (This option is mostly of interest to porters.)
+],
+[BootingFromUnregisterisedHc=YES],
+[BootingFromUnregisterisedHc=NO]
+)
+AC_SUBST(BootingFromUnregisterisedHc)
+
+if test "$BootingFromHc" = "NO"; then
+if test "$BootingFromUnregisterisedHc" = "YES"; then
+AC_MSG_ERROR([--enable-hc-boot-unregisterised requires --enable-hc-boot.])
+fi;
+fi;
+