diff --git a/icn/Makefile.in b/icn/Makefile.in
index 1344f74d..b57bfbf1 100644
--- a/icn/Makefile.in
+++ b/icn/Makefile.in
@@ -6,7 +6,7 @@
 #
 SHELL			= /bin/sh
 CFLAGS			= -Wall -O2
-INCLUDES		= -I. @DEBUGVAR@ -I@KERNELDIR@drivers/isdn/icn
+INCLUDES		= -I. @DEBUGVAR@ -I@KERNELDIR@/drivers/isdn/icn
 DEFS			=
 LDFLAGS			= -L../lib @LIBS@
 PROGRAM			= icnctrl
diff --git a/icn/aclocal.m4 b/icn/aclocal.m4
new file mode 100644
index 00000000..0d5b5a65
--- /dev/null
+++ b/icn/aclocal.m4
@@ -0,0 +1,40 @@
+dnl
+dnl Try finding linux sourcetree
+dnl
+
+AC_DEFUN(AC_FIND_KERNEL, [
+	KERNELDIR=""
+	lxdir="no"
+	tst_kerneldir="$CONFIG_KERNELDIR"
+
+	AC_ARG_WITH(kernel,
+		[  --with-kernel=DIR       Set kernel source directory [/usr/src/linux]],
+		DOTEST="y"; tst_kerneldir="${withval}")
+
+	if test "$DOTEST" = "y" || test "$CONFIG_KERNELDIR" = "y" ; then
+		AC_MSG_CHECKING([for linux kernel source in ${tst_kerneldir}])
+		CPPFLAGS="-nostdinc -I${tst_kerneldir}/drivers/isdn"
+		AC_TRY_CPP([#include <isdn_common.h>], lxdir=${tst_kerneldir},
+		AC_MSG_RESULT("no"))
+	fi
+	if test "$lxdir" = "no" ; then
+		AC_MSG_CHECKING([for linux kernel source in /usr/src/linux])
+		CPPFLAGS="-nostdinc -I/usr/src/linux/drivers/isdn"
+		AC_TRY_CPP([#include <isdn_common.h>], lxdir=/usr/src/linux)
+	fi
+	if test "$lxdir" = "no" ; then
+		AC_MSG_RESULT("$lxdir")
+		AC_MSG_CHECKING([for linux kernel source in /usr/local/src/linux])
+		CPPFLAGS="-nostdinc -I/usr/local/src/linux/drivers/isdn"
+		AC_TRY_CPP([#include <isdn_common.h>], lxdir=/usr/local/src/linux)
+	fi
+	if test "$lxdir" != "no" ; then
+		AC_MSG_RESULT("yes")
+	else
+		lxdir=""
+		AC_MSG_ERROR("Kernel source not found. You MUST specify a correct path to the linux source in the configuration.")
+	fi
+	KERNELDIR="$lxdir"
+	AC_DEFINE_UNQUOTED(KERNELDIR,"$lxdir")
+	AC_SUBST(KERNELDIR)
+])
diff --git a/icn/configure b/icn/configure
index bd353317..fc65d84d 100755
--- a/icn/configure
+++ b/icn/configure
@@ -13,7 +13,9 @@ ac_default_prefix=/usr/local
 # Any additions from configure.in:
 ac_default_prefix=/usr
 ac_help="$ac_help
---enable-dump        Enable dump feature for debugging"
+  --with-kernel=DIR       Set kernel source directory [/usr/src/linux]"
+ac_help="$ac_help
+  --enable-dump           Enable dump feature for debugging"
 
 # Initialize some variables set by options.
 # The variables have the same names as the options, with
@@ -685,7 +687,7 @@ else
   yes;
 #endif
 EOF
-if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:689: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
+if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:691: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
   ac_cv_prog_gcc=yes
 else
   ac_cv_prog_gcc=no
@@ -739,13 +741,13 @@ else
   # On the NeXT, cc -E runs the code through the compiler's parser,
   # not just through cpp.
   cat > conftest.$ac_ext <<EOF
-#line 743 "configure"
+#line 745 "configure"
 #include "confdefs.h"
 #include <assert.h>
 Syntax Error
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:749: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:751: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   :
@@ -754,13 +756,13 @@ else
   rm -rf conftest*
   CPP="${CC-cc} -E -traditional-cpp"
   cat > conftest.$ac_ext <<EOF
-#line 758 "configure"
+#line 760 "configure"
 #include "confdefs.h"
 #include <assert.h>
 Syntax Error
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:764: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:766: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   :
@@ -789,11 +791,11 @@ else
   ac_cv_c_cross=yes
 else
 cat > conftest.$ac_ext <<EOF
-#line 793 "configure"
+#line 795 "configure"
 #include "confdefs.h"
 main(){return(0);}
 EOF
-{ (eval echo configure:797: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
+{ (eval echo configure:799: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
 if test -s conftest && (./conftest; exit) 2>/dev/null; then
   ac_cv_c_cross=no
 else
@@ -811,7 +813,7 @@ if eval "test \"`echo '$''{'ac_cv_header_stdc'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 815 "configure"
+#line 817 "configure"
 #include "confdefs.h"
 #include <stdlib.h>
 #include <stdarg.h>
@@ -819,7 +821,7 @@ else
 #include <float.h>
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:823: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:825: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
@@ -834,7 +836,7 @@ rm -f conftest*
 if test $ac_cv_header_stdc = yes; then
   # SunOS 4.x string.h does not declare mem*, contrary to ANSI.
 cat > conftest.$ac_ext <<EOF
-#line 838 "configure"
+#line 840 "configure"
 #include "confdefs.h"
 #include <string.h>
 EOF
@@ -852,7 +854,7 @@ fi
 if test $ac_cv_header_stdc = yes; then
   # ISC 2.0.2 stdlib.h does not declare free, contrary to ANSI.
 cat > conftest.$ac_ext <<EOF
-#line 856 "configure"
+#line 858 "configure"
 #include "confdefs.h"
 #include <stdlib.h>
 EOF
@@ -873,7 +875,7 @@ if test "$cross_compiling" = yes; then
   :
 else
 cat > conftest.$ac_ext <<EOF
-#line 877 "configure"
+#line 879 "configure"
 #include "confdefs.h"
 #include <ctype.h>
 #define ISLOWER(c) ('a' <= (c) && (c) <= 'z')
@@ -884,7 +886,7 @@ if (XOR (islower (i), ISLOWER (i)) || toupper (i) != TOUPPER (i)) exit(2);
 exit (0); }
 
 EOF
-{ (eval echo configure:888: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
+{ (eval echo configure:890: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
 if test -s conftest && (./conftest; exit) 2>/dev/null; then
   :
 else
@@ -911,12 +913,12 @@ if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 915 "configure"
+#line 917 "configure"
 #include "confdefs.h"
 #include <$ac_hdr>
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:920: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:922: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
@@ -941,7 +943,6 @@ fi
 done
 
 
-
 for ac_hdr in linux/isdn.h
 do
 ac_safe=`echo "$ac_hdr" | tr './\055' '___'`
@@ -950,12 +951,12 @@ if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 954 "configure"
+#line 955 "configure"
 #include "confdefs.h"
 #include <$ac_hdr>
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:959: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:960: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
@@ -973,16 +974,97 @@ if eval "test \"`echo '$ac_cv_header_'$ac_safe`\" = yes"; then
   cat >> confdefs.h <<EOF
 #define $ac_tr_hdr 1
 EOF
- \
-	KERNELDIR="/usr/include/`find /usr/include/linux -maxdepth 0 -printf '%l\n' | sed -e s@include/linux@@`"
+ 
 else
   echo "$ac_t""no" 1>&6
-\
-    { echo "configure: error: "Missing linux/isdn.h. Kernel source installed?"" 1>&2; exit 1; }
 fi
 done
 
 
+	KERNELDIR=""
+	lxdir="no"
+	tst_kerneldir="$CONFIG_KERNELDIR"
+
+	# Check whether --with-kernel or --without-kernel was given.
+if test "${with_kernel+set}" = set; then
+  withval="$with_kernel"
+  DOTEST="y"; tst_kerneldir="${withval}"
+fi
+
+
+	if test "$DOTEST" = "y" || test "$CONFIG_KERNELDIR" = "y" ; then
+		echo $ac_n "checking for linux kernel source in ${tst_kerneldir}""... $ac_c" 1>&6
+		CPPFLAGS="-nostdinc -I${tst_kerneldir}/drivers/isdn"
+		cat > conftest.$ac_ext <<EOF
+#line 1000 "configure"
+#include "confdefs.h"
+#include <isdn_common.h>
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1005: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out`
+if test -z "$ac_err"; then
+  rm -rf conftest*
+  lxdir=${tst_kerneldir}
+else
+  echo "$ac_err" >&5
+  rm -rf conftest*
+  echo "$ac_t"""no"" 1>&6
+fi
+rm -f conftest*
+	fi
+	if test "$lxdir" = "no" ; then
+		echo $ac_n "checking for linux kernel source in /usr/src/linux""... $ac_c" 1>&6
+		CPPFLAGS="-nostdinc -I/usr/src/linux/drivers/isdn"
+		cat > conftest.$ac_ext <<EOF
+#line 1021 "configure"
+#include "confdefs.h"
+#include <isdn_common.h>
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1026: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out`
+if test -z "$ac_err"; then
+  rm -rf conftest*
+  lxdir=/usr/src/linux
+else
+  echo "$ac_err" >&5
+fi
+rm -f conftest*
+	fi
+	if test "$lxdir" = "no" ; then
+		echo "$ac_t"""$lxdir"" 1>&6
+		echo $ac_n "checking for linux kernel source in /usr/local/src/linux""... $ac_c" 1>&6
+		CPPFLAGS="-nostdinc -I/usr/local/src/linux/drivers/isdn"
+		cat > conftest.$ac_ext <<EOF
+#line 1041 "configure"
+#include "confdefs.h"
+#include <isdn_common.h>
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1046: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out`
+if test -z "$ac_err"; then
+  rm -rf conftest*
+  lxdir=/usr/local/src/linux
+else
+  echo "$ac_err" >&5
+fi
+rm -f conftest*
+	fi
+	if test "$lxdir" != "no" ; then
+		echo "$ac_t"""yes"" 1>&6
+	else
+		lxdir=""
+		{ echo "configure: error: "Kernel source not found. You MUST specify a correct path to the linux source in the configuration."" 1>&2; exit 1; }
+	fi
+	KERNELDIR="$lxdir"
+	cat >> confdefs.h <<EOF
+#define KERNELDIR "$lxdir"
+EOF
+
+	
+
 
 
 if test $ac_cv_prog_gcc = yes; then
@@ -992,7 +1074,7 @@ if eval "test \"`echo '$''{'ac_cv_prog_gcc_traditional'+set}'`\" = set"; then
 else
     ac_pattern="Autoconf.*'x'"
   cat > conftest.$ac_ext <<EOF
-#line 996 "configure"
+#line 1078 "configure"
 #include "confdefs.h"
 #include <sgtty.h>
 Autoconf TIOCGETP
@@ -1010,7 +1092,7 @@ rm -f conftest*
 
   if test $ac_cv_prog_gcc_traditional = no; then
     cat > conftest.$ac_ext <<EOF
-#line 1014 "configure"
+#line 1096 "configure"
 #include "confdefs.h"
 #include <termio.h>
 Autoconf TCGETA
@@ -1038,7 +1120,7 @@ if eval "test \"`echo '$''{'ac_cv_func_$ac_func'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1042 "configure"
+#line 1124 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char $ac_func(); below.  */
@@ -1062,7 +1144,7 @@ $ac_func();
 
 ; return 0; }
 EOF
-if { (eval echo configure:1066: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
+if { (eval echo configure:1148: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
   rm -rf conftest*
   eval "ac_cv_func_$ac_func=yes"
 else
@@ -1092,7 +1174,7 @@ else
   ac_cv_func_mmap=no
 else
 cat > conftest.$ac_ext <<EOF
-#line 1096 "configure"
+#line 1178 "configure"
 #include "confdefs.h"
 
 /* Thanks to Mike Haertel and Jim Avera for this test. */
@@ -1161,7 +1243,7 @@ main()
 }
 
 EOF
-{ (eval echo configure:1165: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
+{ (eval echo configure:1247: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
 if test -s conftest && (./conftest; exit) 2>/dev/null; then
   ac_cv_func_mmap=yes
 else
@@ -1193,7 +1275,6 @@ fi
 
 
 
-
 trap '' 1 2 15
 cat > confcache <<\EOF
 # This file is a shell script that caches the results of configure
@@ -1327,8 +1408,8 @@ s%@INSTALL_PROGRAM@%$INSTALL_PROGRAM%g
 s%@INSTALL_DATA@%$INSTALL_DATA%g
 s%@CC@%$CC%g
 s%@CPP@%$CPP%g
-s%@INSTALL@%$INSTALL%g
 s%@KERNELDIR@%$KERNELDIR%g
+s%@INSTALL@%$INSTALL%g
 s%@DEBUGVAR@%$DEBUGVAR%g
 s%@MANDATE@%$MANDATE%g
 s%@I4LCONFDIR@%$I4LCONFDIR%g
diff --git a/icn/configure.in b/icn/configure.in
index 6b0aeea6..f34581ed 100644
--- a/icn/configure.in
+++ b/icn/configure.in
@@ -16,14 +16,9 @@ dnl Checks for header files.
 AC_HEADER_STDC
 AC_CHECK_HEADERS(fcntl.h sys/ioctl.h unistd.h)
 
+AC_CHECK_HEADERS(linux/isdn.h)
 dnl Find current kernel source
-dnl done by dereferencing the symbolic link /usr/include/linux
-dnl and then stripping off include/linux from the result.
-
-AC_CHECK_HEADERS(linux/isdn.h,\
-	KERNELDIR="/usr/include/`find /usr/include/linux -maxdepth 0 -printf '%l\n' | sed -e s@include/linux@@`", \
-    AC_MSG_ERROR("Missing linux/isdn.h. Kernel source installed?"))
-
+AC_FIND_KERNEL
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 
@@ -32,11 +27,10 @@ AC_PROG_GCC_TRADITIONAL
 AC_FUNC_MMAP
 
 dnl Check, if user wants dump option for debugging
-AC_ARG_ENABLE(dump,--enable-dump        Enable dump feature for debugging,\
+AC_ARG_ENABLE(dump,[  --enable-dump           Enable dump feature for debugging],\
 	DEBUGVAR=-D__DEBUGVAR__)
 
 AC_SUBST(INSTALL)
-AC_SUBST(KERNELDIR)
 AC_SUBST(DEBUGVAR)
 AC_SUBST(MANDATE)
 AC_SUBST(I4LCONFDIR)
diff --git a/loop/aclocal.m4 b/loop/aclocal.m4
new file mode 100644
index 00000000..0d5b5a65
--- /dev/null
+++ b/loop/aclocal.m4
@@ -0,0 +1,40 @@
+dnl
+dnl Try finding linux sourcetree
+dnl
+
+AC_DEFUN(AC_FIND_KERNEL, [
+	KERNELDIR=""
+	lxdir="no"
+	tst_kerneldir="$CONFIG_KERNELDIR"
+
+	AC_ARG_WITH(kernel,
+		[  --with-kernel=DIR       Set kernel source directory [/usr/src/linux]],
+		DOTEST="y"; tst_kerneldir="${withval}")
+
+	if test "$DOTEST" = "y" || test "$CONFIG_KERNELDIR" = "y" ; then
+		AC_MSG_CHECKING([for linux kernel source in ${tst_kerneldir}])
+		CPPFLAGS="-nostdinc -I${tst_kerneldir}/drivers/isdn"
+		AC_TRY_CPP([#include <isdn_common.h>], lxdir=${tst_kerneldir},
+		AC_MSG_RESULT("no"))
+	fi
+	if test "$lxdir" = "no" ; then
+		AC_MSG_CHECKING([for linux kernel source in /usr/src/linux])
+		CPPFLAGS="-nostdinc -I/usr/src/linux/drivers/isdn"
+		AC_TRY_CPP([#include <isdn_common.h>], lxdir=/usr/src/linux)
+	fi
+	if test "$lxdir" = "no" ; then
+		AC_MSG_RESULT("$lxdir")
+		AC_MSG_CHECKING([for linux kernel source in /usr/local/src/linux])
+		CPPFLAGS="-nostdinc -I/usr/local/src/linux/drivers/isdn"
+		AC_TRY_CPP([#include <isdn_common.h>], lxdir=/usr/local/src/linux)
+	fi
+	if test "$lxdir" != "no" ; then
+		AC_MSG_RESULT("yes")
+	else
+		lxdir=""
+		AC_MSG_ERROR("Kernel source not found. You MUST specify a correct path to the linux source in the configuration.")
+	fi
+	KERNELDIR="$lxdir"
+	AC_DEFINE_UNQUOTED(KERNELDIR,"$lxdir")
+	AC_SUBST(KERNELDIR)
+])
diff --git a/loop/configure b/loop/configure
index 59ce466a..319820d3 100755
--- a/loop/configure
+++ b/loop/configure
@@ -12,6 +12,8 @@ ac_help=
 ac_default_prefix=/usr/local
 # Any additions from configure.in:
 ac_default_prefix=/usr
+ac_help="$ac_help
+  --with-kernel=DIR       Set kernel source directory [/usr/src/linux]"
 ac_help="$ac_help
 --enable-dump        Enable dump feature for debugging"
 
@@ -685,7 +687,7 @@ else
   yes;
 #endif
 EOF
-if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:689: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
+if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:691: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
   ac_cv_prog_gcc=yes
 else
   ac_cv_prog_gcc=no
@@ -739,13 +741,13 @@ else
   # On the NeXT, cc -E runs the code through the compiler's parser,
   # not just through cpp.
   cat > conftest.$ac_ext <<EOF
-#line 743 "configure"
+#line 745 "configure"
 #include "confdefs.h"
 #include <assert.h>
 Syntax Error
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:749: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:751: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   :
@@ -754,13 +756,13 @@ else
   rm -rf conftest*
   CPP="${CC-cc} -E -traditional-cpp"
   cat > conftest.$ac_ext <<EOF
-#line 758 "configure"
+#line 760 "configure"
 #include "confdefs.h"
 #include <assert.h>
 Syntax Error
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:764: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:766: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   :
@@ -789,11 +791,11 @@ else
   ac_cv_c_cross=yes
 else
 cat > conftest.$ac_ext <<EOF
-#line 793 "configure"
+#line 795 "configure"
 #include "confdefs.h"
 main(){return(0);}
 EOF
-{ (eval echo configure:797: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
+{ (eval echo configure:799: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
 if test -s conftest && (./conftest; exit) 2>/dev/null; then
   ac_cv_c_cross=no
 else
@@ -811,7 +813,7 @@ if eval "test \"`echo '$''{'ac_cv_header_stdc'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 815 "configure"
+#line 817 "configure"
 #include "confdefs.h"
 #include <stdlib.h>
 #include <stdarg.h>
@@ -819,7 +821,7 @@ else
 #include <float.h>
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:823: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:825: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
@@ -834,7 +836,7 @@ rm -f conftest*
 if test $ac_cv_header_stdc = yes; then
   # SunOS 4.x string.h does not declare mem*, contrary to ANSI.
 cat > conftest.$ac_ext <<EOF
-#line 838 "configure"
+#line 840 "configure"
 #include "confdefs.h"
 #include <string.h>
 EOF
@@ -852,7 +854,7 @@ fi
 if test $ac_cv_header_stdc = yes; then
   # ISC 2.0.2 stdlib.h does not declare free, contrary to ANSI.
 cat > conftest.$ac_ext <<EOF
-#line 856 "configure"
+#line 858 "configure"
 #include "confdefs.h"
 #include <stdlib.h>
 EOF
@@ -873,7 +875,7 @@ if test "$cross_compiling" = yes; then
   :
 else
 cat > conftest.$ac_ext <<EOF
-#line 877 "configure"
+#line 879 "configure"
 #include "confdefs.h"
 #include <ctype.h>
 #define ISLOWER(c) ('a' <= (c) && (c) <= 'z')
@@ -884,7 +886,7 @@ if (XOR (islower (i), ISLOWER (i)) || toupper (i) != TOUPPER (i)) exit(2);
 exit (0); }
 
 EOF
-{ (eval echo configure:888: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
+{ (eval echo configure:890: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
 if test -s conftest && (./conftest; exit) 2>/dev/null; then
   :
 else
@@ -911,12 +913,12 @@ if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 915 "configure"
+#line 917 "configure"
 #include "confdefs.h"
 #include <$ac_hdr>
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:920: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:922: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
@@ -941,7 +943,6 @@ fi
 done
 
 
-
 for ac_hdr in linux/isdn.h
 do
 ac_safe=`echo "$ac_hdr" | tr './\055' '___'`
@@ -950,12 +951,12 @@ if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 954 "configure"
+#line 955 "configure"
 #include "confdefs.h"
 #include <$ac_hdr>
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:959: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:960: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
@@ -973,16 +974,97 @@ if eval "test \"`echo '$ac_cv_header_'$ac_safe`\" = yes"; then
   cat >> confdefs.h <<EOF
 #define $ac_tr_hdr 1
 EOF
- \
-	KERNELDIR="/usr/include/`find /usr/include/linux -maxdepth 0 -printf '%l\n' | sed -e s@include/linux@@`"
+ 
 else
   echo "$ac_t""no" 1>&6
-\
-    { echo "configure: error: "Missing linux/isdn.h. Kernel source installed?"" 1>&2; exit 1; }
 fi
 done
 
 
+	KERNELDIR=""
+	lxdir="no"
+	tst_kerneldir="$CONFIG_KERNELDIR"
+
+	# Check whether --with-kernel or --without-kernel was given.
+if test "${with_kernel+set}" = set; then
+  withval="$with_kernel"
+  DOTEST="y"; tst_kerneldir="${withval}"
+fi
+
+
+	if test "$DOTEST" = "y" || test "$CONFIG_KERNELDIR" = "y" ; then
+		echo $ac_n "checking for linux kernel source in ${tst_kerneldir}""... $ac_c" 1>&6
+		CPPFLAGS="-nostdinc -I${tst_kerneldir}/drivers/isdn"
+		cat > conftest.$ac_ext <<EOF
+#line 1000 "configure"
+#include "confdefs.h"
+#include <isdn_common.h>
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1005: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out`
+if test -z "$ac_err"; then
+  rm -rf conftest*
+  lxdir=${tst_kerneldir}
+else
+  echo "$ac_err" >&5
+  rm -rf conftest*
+  echo "$ac_t"""no"" 1>&6
+fi
+rm -f conftest*
+	fi
+	if test "$lxdir" = "no" ; then
+		echo $ac_n "checking for linux kernel source in /usr/src/linux""... $ac_c" 1>&6
+		CPPFLAGS="-nostdinc -I/usr/src/linux/drivers/isdn"
+		cat > conftest.$ac_ext <<EOF
+#line 1021 "configure"
+#include "confdefs.h"
+#include <isdn_common.h>
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1026: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out`
+if test -z "$ac_err"; then
+  rm -rf conftest*
+  lxdir=/usr/src/linux
+else
+  echo "$ac_err" >&5
+fi
+rm -f conftest*
+	fi
+	if test "$lxdir" = "no" ; then
+		echo "$ac_t"""$lxdir"" 1>&6
+		echo $ac_n "checking for linux kernel source in /usr/local/src/linux""... $ac_c" 1>&6
+		CPPFLAGS="-nostdinc -I/usr/local/src/linux/drivers/isdn"
+		cat > conftest.$ac_ext <<EOF
+#line 1041 "configure"
+#include "confdefs.h"
+#include <isdn_common.h>
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1046: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out`
+if test -z "$ac_err"; then
+  rm -rf conftest*
+  lxdir=/usr/local/src/linux
+else
+  echo "$ac_err" >&5
+fi
+rm -f conftest*
+	fi
+	if test "$lxdir" != "no" ; then
+		echo "$ac_t"""yes"" 1>&6
+	else
+		lxdir=""
+		{ echo "configure: error: "Kernel source not found. You MUST specify a correct path to the linux source in the configuration."" 1>&2; exit 1; }
+	fi
+	KERNELDIR="$lxdir"
+	cat >> confdefs.h <<EOF
+#define KERNELDIR "$lxdir"
+EOF
+
+	
+
 
 
 if test $ac_cv_prog_gcc = yes; then
@@ -992,7 +1074,7 @@ if eval "test \"`echo '$''{'ac_cv_prog_gcc_traditional'+set}'`\" = set"; then
 else
     ac_pattern="Autoconf.*'x'"
   cat > conftest.$ac_ext <<EOF
-#line 996 "configure"
+#line 1078 "configure"
 #include "confdefs.h"
 #include <sgtty.h>
 Autoconf TIOCGETP
@@ -1010,7 +1092,7 @@ rm -f conftest*
 
   if test $ac_cv_prog_gcc_traditional = no; then
     cat > conftest.$ac_ext <<EOF
-#line 1014 "configure"
+#line 1096 "configure"
 #include "confdefs.h"
 #include <termio.h>
 Autoconf TCGETA
@@ -1038,7 +1120,7 @@ if eval "test \"`echo '$''{'ac_cv_func_$ac_func'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1042 "configure"
+#line 1124 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char $ac_func(); below.  */
@@ -1062,7 +1144,7 @@ $ac_func();
 
 ; return 0; }
 EOF
-if { (eval echo configure:1066: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
+if { (eval echo configure:1148: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
   rm -rf conftest*
   eval "ac_cv_func_$ac_func=yes"
 else
@@ -1092,7 +1174,7 @@ else
   ac_cv_func_mmap=no
 else
 cat > conftest.$ac_ext <<EOF
-#line 1096 "configure"
+#line 1178 "configure"
 #include "confdefs.h"
 
 /* Thanks to Mike Haertel and Jim Avera for this test. */
@@ -1161,7 +1243,7 @@ main()
 }
 
 EOF
-{ (eval echo configure:1165: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
+{ (eval echo configure:1247: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
 if test -s conftest && (./conftest; exit) 2>/dev/null; then
   ac_cv_func_mmap=yes
 else
@@ -1193,7 +1275,6 @@ fi
 
 
 
-
 trap '' 1 2 15
 cat > confcache <<\EOF
 # This file is a shell script that caches the results of configure
@@ -1327,8 +1408,8 @@ s%@INSTALL_PROGRAM@%$INSTALL_PROGRAM%g
 s%@INSTALL_DATA@%$INSTALL_DATA%g
 s%@CC@%$CC%g
 s%@CPP@%$CPP%g
-s%@INSTALL@%$INSTALL%g
 s%@KERNELDIR@%$KERNELDIR%g
+s%@INSTALL@%$INSTALL%g
 s%@DEBUGVAR@%$DEBUGVAR%g
 s%@MANDATE@%$MANDATE%g
 s%@I4LCONFDIR@%$I4LCONFDIR%g
diff --git a/loop/configure.in b/loop/configure.in
index 6e1482bb..dbc7667d 100644
--- a/loop/configure.in
+++ b/loop/configure.in
@@ -16,14 +16,9 @@ dnl Checks for header files.
 AC_HEADER_STDC
 AC_CHECK_HEADERS(fcntl.h sys/ioctl.h unistd.h)
 
+AC_CHECK_HEADERS(linux/isdn.h)
 dnl Find current kernel source
-dnl done by dereferencing the symbolic link /usr/include/linux
-dnl and then stripping off include/linux from the result.
-
-AC_CHECK_HEADERS(linux/isdn.h,\
-	KERNELDIR="/usr/include/`find /usr/include/linux -maxdepth 0 -printf '%l\n' | sed -e s@include/linux@@`", \
-    AC_MSG_ERROR("Missing linux/isdn.h. Kernel source installed?"))
-
+AC_FIND_KERNEL
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 
@@ -36,7 +31,6 @@ AC_ARG_ENABLE(dump,--enable-dump        Enable dump feature for debugging,\
 	DEBUGVAR=-D__DEBUGVAR__)
 
 AC_SUBST(INSTALL)
-AC_SUBST(KERNELDIR)
 AC_SUBST(DEBUGVAR)
 AC_SUBST(MANDATE)
 AC_SUBST(I4LCONFDIR)
diff --git a/pcbit/Makefile.in b/pcbit/Makefile.in
index 5d759fd0..a894a00b 100644
--- a/pcbit/Makefile.in
+++ b/pcbit/Makefile.in
@@ -6,7 +6,7 @@
 #
 SHELL			= /bin/sh
 CFLAGS			= -Wall -Wstrict-prototypes -O2 -g
-INCLUDES		= -I. -DDEBUG -I@KERNELDIR@drivers/isdn/pcbit
+INCLUDES		= -I. -DDEBUG -I@KERNELDIR@/drivers/isdn/pcbit
 LDFLAGS			= -L../lib @LIBS@
 PROGRAM			= pcbitctl
 MODULES			= pcbitctl.o convhexbin.o
diff --git a/pcbit/aclocal.m4 b/pcbit/aclocal.m4
new file mode 100644
index 00000000..0d5b5a65
--- /dev/null
+++ b/pcbit/aclocal.m4
@@ -0,0 +1,40 @@
+dnl
+dnl Try finding linux sourcetree
+dnl
+
+AC_DEFUN(AC_FIND_KERNEL, [
+	KERNELDIR=""
+	lxdir="no"
+	tst_kerneldir="$CONFIG_KERNELDIR"
+
+	AC_ARG_WITH(kernel,
+		[  --with-kernel=DIR       Set kernel source directory [/usr/src/linux]],
+		DOTEST="y"; tst_kerneldir="${withval}")
+
+	if test "$DOTEST" = "y" || test "$CONFIG_KERNELDIR" = "y" ; then
+		AC_MSG_CHECKING([for linux kernel source in ${tst_kerneldir}])
+		CPPFLAGS="-nostdinc -I${tst_kerneldir}/drivers/isdn"
+		AC_TRY_CPP([#include <isdn_common.h>], lxdir=${tst_kerneldir},
+		AC_MSG_RESULT("no"))
+	fi
+	if test "$lxdir" = "no" ; then
+		AC_MSG_CHECKING([for linux kernel source in /usr/src/linux])
+		CPPFLAGS="-nostdinc -I/usr/src/linux/drivers/isdn"
+		AC_TRY_CPP([#include <isdn_common.h>], lxdir=/usr/src/linux)
+	fi
+	if test "$lxdir" = "no" ; then
+		AC_MSG_RESULT("$lxdir")
+		AC_MSG_CHECKING([for linux kernel source in /usr/local/src/linux])
+		CPPFLAGS="-nostdinc -I/usr/local/src/linux/drivers/isdn"
+		AC_TRY_CPP([#include <isdn_common.h>], lxdir=/usr/local/src/linux)
+	fi
+	if test "$lxdir" != "no" ; then
+		AC_MSG_RESULT("yes")
+	else
+		lxdir=""
+		AC_MSG_ERROR("Kernel source not found. You MUST specify a correct path to the linux source in the configuration.")
+	fi
+	KERNELDIR="$lxdir"
+	AC_DEFINE_UNQUOTED(KERNELDIR,"$lxdir")
+	AC_SUBST(KERNELDIR)
+])
diff --git a/pcbit/configure b/pcbit/configure
index 134c3b24..29406d18 100755
--- a/pcbit/configure
+++ b/pcbit/configure
@@ -12,6 +12,8 @@ ac_help=
 ac_default_prefix=/usr/local
 # Any additions from configure.in:
 ac_default_prefix=/usr
+ac_help="$ac_help
+  --with-kernel=DIR       Set kernel source directory [/usr/src/linux]"
 
 # Initialize some variables set by options.
 # The variables have the same names as the options, with
@@ -601,7 +603,7 @@ else
   yes;
 #endif
 EOF
-if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:605: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
+if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:607: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
   ac_cv_prog_gcc=yes
 else
   ac_cv_prog_gcc=no
@@ -733,13 +735,13 @@ else
   # On the NeXT, cc -E runs the code through the compiler's parser,
   # not just through cpp.
   cat > conftest.$ac_ext <<EOF
-#line 737 "configure"
+#line 739 "configure"
 #include "confdefs.h"
 #include <assert.h>
 Syntax Error
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:743: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:745: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   :
@@ -748,13 +750,13 @@ else
   rm -rf conftest*
   CPP="${CC-cc} -E -traditional-cpp"
   cat > conftest.$ac_ext <<EOF
-#line 752 "configure"
+#line 754 "configure"
 #include "confdefs.h"
 #include <assert.h>
 Syntax Error
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:758: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:760: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   :
@@ -783,11 +785,11 @@ else
   ac_cv_c_cross=yes
 else
 cat > conftest.$ac_ext <<EOF
-#line 787 "configure"
+#line 789 "configure"
 #include "confdefs.h"
 main(){return(0);}
 EOF
-{ (eval echo configure:791: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
+{ (eval echo configure:793: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
 if test -s conftest && (./conftest; exit) 2>/dev/null; then
   ac_cv_c_cross=no
 else
@@ -805,7 +807,7 @@ if eval "test \"`echo '$''{'ac_cv_header_stdc'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 809 "configure"
+#line 811 "configure"
 #include "confdefs.h"
 #include <stdlib.h>
 #include <stdarg.h>
@@ -813,7 +815,7 @@ else
 #include <float.h>
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:817: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:819: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
@@ -828,7 +830,7 @@ rm -f conftest*
 if test $ac_cv_header_stdc = yes; then
   # SunOS 4.x string.h does not declare mem*, contrary to ANSI.
 cat > conftest.$ac_ext <<EOF
-#line 832 "configure"
+#line 834 "configure"
 #include "confdefs.h"
 #include <string.h>
 EOF
@@ -846,7 +848,7 @@ fi
 if test $ac_cv_header_stdc = yes; then
   # ISC 2.0.2 stdlib.h does not declare free, contrary to ANSI.
 cat > conftest.$ac_ext <<EOF
-#line 850 "configure"
+#line 852 "configure"
 #include "confdefs.h"
 #include <stdlib.h>
 EOF
@@ -867,7 +869,7 @@ if test "$cross_compiling" = yes; then
   :
 else
 cat > conftest.$ac_ext <<EOF
-#line 871 "configure"
+#line 873 "configure"
 #include "confdefs.h"
 #include <ctype.h>
 #define ISLOWER(c) ('a' <= (c) && (c) <= 'z')
@@ -878,7 +880,7 @@ if (XOR (islower (i), ISLOWER (i)) || toupper (i) != TOUPPER (i)) exit(2);
 exit (0); }
 
 EOF
-{ (eval echo configure:882: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
+{ (eval echo configure:884: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }
 if test -s conftest && (./conftest; exit) 2>/dev/null; then
   :
 else
@@ -905,12 +907,12 @@ if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 909 "configure"
+#line 911 "configure"
 #include "confdefs.h"
 #include <$ac_hdr>
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:914: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:916: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
@@ -935,7 +937,6 @@ fi
 done
 
 
-
 for ac_hdr in linux/isdn.h
 do
 ac_safe=`echo "$ac_hdr" | tr './\055' '___'`
@@ -944,12 +945,12 @@ if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 948 "configure"
+#line 949 "configure"
 #include "confdefs.h"
 #include <$ac_hdr>
 EOF
 ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
-{ (eval echo configure:953: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+{ (eval echo configure:954: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
 ac_err=`grep -v '^ *+' conftest.out`
 if test -z "$ac_err"; then
   rm -rf conftest*
@@ -967,16 +968,98 @@ if eval "test \"`echo '$ac_cv_header_'$ac_safe`\" = yes"; then
   cat >> confdefs.h <<EOF
 #define $ac_tr_hdr 1
 EOF
- \
-	KERNELDIR="/usr/include/`find /usr/include/linux -maxdepth 0 -printf '%l\n' | sed -e s@include/linux@@`"
+ 
 else
   echo "$ac_t""no" 1>&6
-\
-    { echo "configure: error: "Missing linux/isdn.h. Kernel source installed?"" 1>&2; exit 1; }
 fi
 done
 
 
+	KERNELDIR=""
+	lxdir="no"
+	tst_kerneldir="$CONFIG_KERNELDIR"
+
+	# Check whether --with-kernel or --without-kernel was given.
+if test "${with_kernel+set}" = set; then
+  withval="$with_kernel"
+  DOTEST="y"; tst_kerneldir="${withval}"
+fi
+
+
+	if test "$DOTEST" = "y" || test "$CONFIG_KERNELDIR" = "y" ; then
+		echo $ac_n "checking for linux kernel source in ${tst_kerneldir}""... $ac_c" 1>&6
+		CPPFLAGS="-nostdinc -I${tst_kerneldir}/drivers/isdn"
+		cat > conftest.$ac_ext <<EOF
+#line 994 "configure"
+#include "confdefs.h"
+#include <isdn_common.h>
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:999: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out`
+if test -z "$ac_err"; then
+  rm -rf conftest*
+  lxdir=${tst_kerneldir}
+else
+  echo "$ac_err" >&5
+  rm -rf conftest*
+  echo "$ac_t"""no"" 1>&6
+fi
+rm -f conftest*
+	fi
+	if test "$lxdir" = "no" ; then
+		echo $ac_n "checking for linux kernel source in /usr/src/linux""... $ac_c" 1>&6
+		CPPFLAGS="-nostdinc -I/usr/src/linux/drivers/isdn"
+		cat > conftest.$ac_ext <<EOF
+#line 1015 "configure"
+#include "confdefs.h"
+#include <isdn_common.h>
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1020: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out`
+if test -z "$ac_err"; then
+  rm -rf conftest*
+  lxdir=/usr/src/linux
+else
+  echo "$ac_err" >&5
+fi
+rm -f conftest*
+	fi
+	if test "$lxdir" = "no" ; then
+		echo "$ac_t"""$lxdir"" 1>&6
+		echo $ac_n "checking for linux kernel source in /usr/local/src/linux""... $ac_c" 1>&6
+		CPPFLAGS="-nostdinc -I/usr/local/src/linux/drivers/isdn"
+		cat > conftest.$ac_ext <<EOF
+#line 1035 "configure"
+#include "confdefs.h"
+#include <isdn_common.h>
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1040: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out`
+if test -z "$ac_err"; then
+  rm -rf conftest*
+  lxdir=/usr/local/src/linux
+else
+  echo "$ac_err" >&5
+fi
+rm -f conftest*
+	fi
+	if test "$lxdir" != "no" ; then
+		echo "$ac_t"""yes"" 1>&6
+	else
+		lxdir=""
+		{ echo "configure: error: "Kernel source not found. You MUST specify a correct path to the linux source in the configuration."" 1>&2; exit 1; }
+	fi
+	KERNELDIR="$lxdir"
+	cat >> confdefs.h <<EOF
+#define KERNELDIR "$lxdir"
+EOF
+
+	
+
+
 
 if test $ac_cv_prog_gcc = yes; then
     echo $ac_n "checking whether ${CC-cc} needs -traditional""... $ac_c" 1>&6
@@ -985,7 +1068,7 @@ if eval "test \"`echo '$''{'ac_cv_prog_gcc_traditional'+set}'`\" = set"; then
 else
     ac_pattern="Autoconf.*'x'"
   cat > conftest.$ac_ext <<EOF
-#line 989 "configure"
+#line 1072 "configure"
 #include "confdefs.h"
 #include <sgtty.h>
 Autoconf TIOCGETP
@@ -1003,7 +1086,7 @@ rm -f conftest*
 
   if test $ac_cv_prog_gcc_traditional = no; then
     cat > conftest.$ac_ext <<EOF
-#line 1007 "configure"
+#line 1090 "configure"
 #include "confdefs.h"
 #include <termio.h>
 Autoconf TCGETA
@@ -1031,7 +1114,7 @@ if eval "test \"`echo '$''{'ac_cv_func_$ac_func'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1035 "configure"
+#line 1118 "configure"
 #include "confdefs.h"
 /* System header to define __stub macros and hopefully few prototypes,
     which can conflict with char $ac_func(); below.  */
@@ -1055,7 +1138,7 @@ $ac_func();
 
 ; return 0; }
 EOF
-if { (eval echo configure:1059: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
+if { (eval echo configure:1142: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
   rm -rf conftest*
   eval "ac_cv_func_$ac_func=yes"
 else
@@ -1079,7 +1162,6 @@ done
 
 
 
-
 trap '' 1 2 15
 cat > confcache <<\EOF
 # This file is a shell script that caches the results of configure
@@ -1213,8 +1295,8 @@ s%@CC@%$CC%g
 s%@INSTALL_PROGRAM@%$INSTALL_PROGRAM%g
 s%@INSTALL_DATA@%$INSTALL_DATA%g
 s%@CPP@%$CPP%g
-s%@INSTALL@%$INSTALL%g
 s%@KERNELDIR@%$KERNELDIR%g
+s%@INSTALL@%$INSTALL%g
 
 CEOF
 EOF
diff --git a/pcbit/configure.in b/pcbit/configure.in
index a646ebbf..2c1fb12e 100644
--- a/pcbit/configure.in
+++ b/pcbit/configure.in
@@ -12,13 +12,9 @@ dnl Checks for header files.
 AC_HEADER_STDC
 AC_CHECK_HEADERS(fcntl.h sys/ioctl.h unistd.h)
 
+AC_CHECK_HEADERS(linux/isdn.h)
 dnl Find current kernel source
-dnl done by dereferencing the symbolic link /usr/include/linux
-dnl and then stripping off include/linux from the result.
-
-AC_CHECK_HEADERS(linux/isdn.h,\
-	KERNELDIR="/usr/include/`find /usr/include/linux -maxdepth 0 -printf '%l\n' | sed -e s@include/linux@@`", \
-    AC_MSG_ERROR("Missing linux/isdn.h. Kernel source installed?"))
+AC_FIND_KERNEL
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 
@@ -27,5 +23,4 @@ AC_PROG_GCC_TRADITIONAL
 AC_CHECK_FUNCS(strerror)
 
 AC_SUBST(INSTALL)
-AC_SUBST(KERNELDIR)
 AC_OUTPUT(Makefile)
diff --git a/scripts/config.in b/scripts/config.in
index ce4d5b61..2c96234d 100644
--- a/scripts/config.in
+++ b/scripts/config.in
@@ -20,6 +20,7 @@ mainmenu_option next_comment
 comment 'General configuration'
 comment 'Build options'
 dep_bool 'Build programs which need X11 installed' CONFIG_BUILDX11 $CONFIG_HASX11
+string 'Kernel source directory' CONFIG_KERNELDIR
 comment 'Destination directories'
 string 'Directory to install binaries' CONFIG_BINDIR
 string 'Directory to install admin binaries' CONFIG_SBINDIR
diff --git a/scripts/defconfig b/scripts/defconfig
index 549741ba..139910df 100644
--- a/scripts/defconfig
+++ b/scripts/defconfig
@@ -11,6 +11,7 @@ CONFIG_EXPERIMENTAL=n
 # General configuration
 #
 CONFIG_BUILDX11=y
+CONFIG_KERNELDIR='/usr/src/linux'
 CONFIG_BINDIR='/usr/bin'
 CONFIG_SBINDIR='/sbin'
 CONFIG_MANDIR='/usr/man'