diff -up /dev/null gmp-4.2.2/mpn/s390x/gmp-mparam.h
--- /dev/null	2008-09-01 10:12:52.609021969 +0200
+++ gmp-4.2.2/mpn/s390x/gmp-mparam.h	2008-09-01 13:04:05.000000000 +0200
@@ -0,0 +1,27 @@
+/* gmp-mparam.h -- Compiler/machine parameter header file.
+
+Copyright (C) 1991, 1993, 1994, 1995 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of the GNU Library General Public License as published by
+the Free Software Foundation; either version 2 of the License, or (at your
+option) any later version.
+
+The GNU MP Library is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
+License for more details.
+
+You should have received a copy of the GNU Library General Public License
+along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+MA 02111-1307, USA. */
+
+#define BITS_PER_MP_LIMB 64
+#define BYTES_PER_MP_LIMB 8
+#define BITS_PER_LONGINT 64
+#define BITS_PER_INT 32
+#define BITS_PER_SHORTINT 16
+#define BITS_PER_CHAR 8
diff -up gmp-4.2.2/mpn/s390/gmp-mparam.h.s390 gmp-4.2.2/mpn/s390/gmp-mparam.h
--- gmp-4.2.2/mpn/s390/gmp-mparam.h.s390	2007-08-30 20:31:41.000000000 +0200
+++ gmp-4.2.2/mpn/s390/gmp-mparam.h	2008-09-01 13:04:05.000000000 +0200
@@ -18,7 +18,8 @@ You should have received a copy of the G
 along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
 
 
-/* BITS_PER_MP_LIMB etc generated by configure */
+#define BITS_PER_MP_LIMB 32
+#define BYTES_PER_MP_LIMB 4
 
 
 /* Generated by tuneup.c, 2001-12-03, gcc 2.95 */
diff -up gmp-4.2.2/configure.in.s390 gmp-4.2.2/configure.in
--- gmp-4.2.2/configure.in.s390	2007-09-09 18:39:14.000000000 +0200
+++ gmp-4.2.2/configure.in	2008-09-01 13:04:05.000000000 +0200
@@ -1054,6 +1054,11 @@ case $host in
     ;;
 
 
+  s390x-*-*)
+    gcc_cflags="-g -O2 $fomit_frame_pointer"
+    path="s390x"
+    #extra_functions="udiv_w_sdiv"
+    ;;
   # IBM s/370 and similar
   [s3[6-9]0*-*-*])
     gcc_cflags="-O2 $fomit_frame_pointer"