tools: disable building qemu-trad per default

Using qemu-traditional as device model is deprecated for some time now.

So change the default for building it to "disable". This will affect
ioemu-stubdom, too, as there is a direct dependency between the two.

Today it is possible to use a PVH/HVM Linux-based stubdom as device
model. Additionally using ioemu-stubdom isn't really helping for
security, as it requires to run a very old and potentially buggy qemu
version in a PV domain. This is adding probably more security problems
than it is removing by using a stubdom.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Acked-by: Ian Jackson <iwj@xenproject.org>
Release-acked-by: Ian Jackson <iwj@xenproject.org>

tools/configure.ac

@@ -120,18 +120,7 @@ AC_SUBST(LINUX_BACKEND_MODULES)
 
 AC_ARG_ENABLE([qemu-traditional],
     AS_HELP_STRING([--enable-qemu-traditional],
-                   [Enable qemu traditional device model, (DEFAULT is on for Linux or NetBSD x86, otherwise off)]),,[
-    case "$host_cpu" in
-        i[[3456]]86|x86_64)
-           enable_qemu_traditional="yes";;
-        *) enable_qemu_traditional="no";;
-    esac
-    case "$host_os" in
-        freebsd*)
-           enable_qemu_traditional="no";;
-    esac
-
-])
+                   [Enable qemu traditional device model, (DEFAULT is off)]))
 AS_IF([test "x$enable_qemu_traditional" = "xyes"], [
 AC_DEFINE([HAVE_QEMU_TRADITIONAL], [1], [Qemu traditional enabled])
     qemu_traditional=y],[