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changeset 352:1f5fe8f482d9

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Only support I/O through the ethertap device if running a sufficiently recent Linux kernel
author bartv
date Wed, 25 Sep 2002 19:53:54 +0000
parents 58836890b2a0
children 9c7f9b4dfb2f
files packages/devs/eth/synth/ecosynth/current/ChangeLog packages/devs/eth/synth/ecosynth/current/doc/devs-eth-synth-ecosynth.html packages/devs/eth/synth/ecosynth/current/doc/syntheth.sgml packages/devs/eth/synth/ecosynth/current/host/configure packages/devs/eth/synth/ecosynth/current/host/configure.in packages/devs/eth/synth/ecosynth/current/host/rawether.c
diffstat 6 files changed, 255 insertions(+), 64 deletions(-) [+]
line wrap: on
line diff
--- a/packages/devs/eth/synth/ecosynth/current/ChangeLog
+++ b/packages/devs/eth/synth/ecosynth/current/ChangeLog
@@ -1,3 +1,8 @@
+2002-09-25  Bart Veer  <bartv@ecoscentric.com>
+
+	* host/configure.in, host/rawether.c, doc/syntheth.sgml: 
+	Only support the tap device if running a recent Linux kernel
+
 2002-09-22  Bart Veer  <bartv@ecoscentric.com>
 
 	* host/configure.in:
--- a/packages/devs/eth/synth/ecosynth/current/doc/devs-eth-synth-ecosynth.html
+++ b/packages/devs/eth/synth/ecosynth/current/doc/devs-eth-synth-ecosynth.html
@@ -3,9 +3,6 @@
 <!-- and conditions set forth in the Open Publication License, v1.0  -->
 <!-- or later (the latest version is presently available at          -->
 <!-- http://www.opencontent.org/openpub/).                           -->
-<!-- Distribution of substantively modified versions of this         -->
-<!-- document is prohibited without the explicit permission of the   -->
-<!-- copyright holder.                                               -->
 <!-- Distribution of the work or derivative of the work in any       -->
 <!-- standard (paper) book form is prohibited unless prior           -->
 <!-- permission is obtained from the copyright holder.               -->
@@ -428,6 +425,25 @@ documentation should be consulted, for e
 CLASS="FILENAME"
 >/usr/src/linux-2.4/Documentation/networking/tuntap.txt</TT
 >.
+If you are using an old Linux kernel then the ethertap functionality
+may be missing completely. When the <B
+CLASS="COMMAND"
+>rawether</B
+>
+program is configured and built, the <B
+CLASS="COMMAND"
+>configure</B
+>
+script will check for a file <TT
+CLASS="FILENAME"
+>/usr/include/linux/if_tun.h</TT
+>. If that
+file is missing then <B
+CLASS="COMMAND"
+>rawether</B
+> will be built without
+ethertap functionality, and only real ethernet interfaces will be
+supported.
     </P
 ><P
 >The target definition file is used to map eCos network devices on to
--- a/packages/devs/eth/synth/ecosynth/current/doc/syntheth.sgml
+++ b/packages/devs/eth/synth/ecosynth/current/doc/syntheth.sgml
@@ -237,6 +237,14 @@ your system does not have a device <file
 or a module <filename>tun.o</filename> then the appropriate kernel
 documentation should be consulted, for example
 <filename>/usr/src/linux-2.4/Documentation/networking/tuntap.txt</filename>.
+If you are using an old Linux kernel then the ethertap functionality
+may be missing completely. When the <command>rawether</command>
+program is configured and built, the <command>configure</command>
+script will check for a file <filename
+class="headerfile">/usr/include/linux/if_tun.h</filename>. If that
+file is missing then <command>rawether</command> will be built without
+ethertap functionality, and only real ethernet interfaces will be
+supported.
     </para>
     <para>
 The target definition file is used to map eCos network devices on to
--- a/packages/devs/eth/synth/ecosynth/current/host/configure
+++ b/packages/devs/eth/synth/ecosynth/current/host/configure
@@ -844,12 +844,15 @@ case "${host}" in
     i[34567]86-*-linux-gnu* ) SUPPORTED="yes";;
     * ) SUPPORTED="no"
 esac
+if test "${SUPPORTED}" = "no" ; then
+    echo "configure: warning: Synthetic target ethernet support is only available on x86 Linux hosts" 1>&2
+fi   
 
 if test "${SUPPORTED}" = "yes" ; then
     # Extract the first word of "gcc", so it can be a program name with args.
 set dummy gcc; ac_word=$2
 echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
-echo "configure:853: checking for $ac_word" >&5
+echo "configure:856: checking for $ac_word" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_CC'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -879,7 +882,7 @@ if test -z "$CC"; then
   # Extract the first word of "cc", so it can be a program name with args.
 set dummy cc; ac_word=$2
 echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
-echo "configure:883: checking for $ac_word" >&5
+echo "configure:886: checking for $ac_word" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_CC'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -930,7 +933,7 @@ fi
       # Extract the first word of "cl", so it can be a program name with args.
 set dummy cl; ac_word=$2
 echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
-echo "configure:934: checking for $ac_word" >&5
+echo "configure:937: checking for $ac_word" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_CC'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -962,7 +965,7 @@ fi
 fi
 
 echo $ac_n "checking whether the C compiler ($CC $CFLAGS $LDFLAGS) works""... $ac_c" 1>&6
-echo "configure:966: checking whether the C compiler ($CC $CFLAGS $LDFLAGS) works" >&5
+echo "configure:969: checking whether the C compiler ($CC $CFLAGS $LDFLAGS) works" >&5
 
 ac_ext=c
 # CFLAGS is not in ac_cpp because -g, -O, etc. are not valid cpp options.
@@ -973,12 +976,12 @@ cross_compiling=$ac_cv_prog_cc_cross
 
 cat > conftest.$ac_ext << EOF
 
-#line 977 "configure"
+#line 980 "configure"
 #include "confdefs.h"
 
 main(){return(0);}
 EOF
-if { (eval echo configure:982: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:985: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   ac_cv_prog_cc_works=yes
   # If we can't run a trivial program, we are probably using a cross compiler.
   if (./conftest; exit) 2>/dev/null; then
@@ -1004,12 +1007,12 @@ if test $ac_cv_prog_cc_works = no; then
   { echo "configure: error: installation or configuration problem: C compiler cannot create executables." 1>&2; exit 1; }
 fi
 echo $ac_n "checking whether the C compiler ($CC $CFLAGS $LDFLAGS) is a cross-compiler""... $ac_c" 1>&6
-echo "configure:1008: checking whether the C compiler ($CC $CFLAGS $LDFLAGS) is a cross-compiler" >&5
+echo "configure:1011: checking whether the C compiler ($CC $CFLAGS $LDFLAGS) is a cross-compiler" >&5
 echo "$ac_t""$ac_cv_prog_cc_cross" 1>&6
 cross_compiling=$ac_cv_prog_cc_cross
 
 echo $ac_n "checking whether we are using GNU C""... $ac_c" 1>&6
-echo "configure:1013: checking whether we are using GNU C" >&5
+echo "configure:1016: checking whether we are using GNU C" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_gcc'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -1018,7 +1021,7 @@ else
   yes;
 #endif
 EOF
-if { ac_try='${CC-cc} -E conftest.c'; { (eval echo configure:1022: \"$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:1025: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
   ac_cv_prog_gcc=yes
 else
   ac_cv_prog_gcc=no
@@ -1037,7 +1040,7 @@ ac_test_CFLAGS="${CFLAGS+set}"
 ac_save_CFLAGS="$CFLAGS"
 CFLAGS=
 echo $ac_n "checking whether ${CC-cc} accepts -g""... $ac_c" 1>&6
-echo "configure:1041: checking whether ${CC-cc} accepts -g" >&5
+echo "configure:1044: checking whether ${CC-cc} accepts -g" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_cc_g'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -1073,7 +1076,7 @@ do
 # Extract the first word of "$ac_prog", so it can be a program name with args.
 set dummy $ac_prog; ac_word=$2
 echo $ac_n "checking for $ac_word""... $ac_c" 1>&6
-echo "configure:1077: checking for $ac_word" >&5
+echo "configure:1080: checking for $ac_word" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_CXX'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -1105,7 +1108,7 @@ test -n "$CXX" || CXX="gcc"
 
 
 echo $ac_n "checking whether the C++ compiler ($CXX $CXXFLAGS $LDFLAGS) works""... $ac_c" 1>&6
-echo "configure:1109: checking whether the C++ compiler ($CXX $CXXFLAGS $LDFLAGS) works" >&5
+echo "configure:1112: checking whether the C++ compiler ($CXX $CXXFLAGS $LDFLAGS) works" >&5
 
 ac_ext=C
 # CXXFLAGS is not in ac_cpp because -g, -O, etc. are not valid cpp options.
@@ -1116,12 +1119,12 @@ cross_compiling=$ac_cv_prog_cxx_cross
 
 cat > conftest.$ac_ext << EOF
 
-#line 1120 "configure"
+#line 1123 "configure"
 #include "confdefs.h"
 
 int main(){return(0);}
 EOF
-if { (eval echo configure:1125: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
+if { (eval echo configure:1128: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; } && test -s conftest${ac_exeext}; then
   ac_cv_prog_cxx_works=yes
   # If we can't run a trivial program, we are probably using a cross compiler.
   if (./conftest; exit) 2>/dev/null; then
@@ -1147,12 +1150,12 @@ if test $ac_cv_prog_cxx_works = no; then
   { echo "configure: error: installation or configuration problem: C++ compiler cannot create executables." 1>&2; exit 1; }
 fi
 echo $ac_n "checking whether the C++ compiler ($CXX $CXXFLAGS $LDFLAGS) is a cross-compiler""... $ac_c" 1>&6
-echo "configure:1151: checking whether the C++ compiler ($CXX $CXXFLAGS $LDFLAGS) is a cross-compiler" >&5
+echo "configure:1154: checking whether the C++ compiler ($CXX $CXXFLAGS $LDFLAGS) is a cross-compiler" >&5
 echo "$ac_t""$ac_cv_prog_cxx_cross" 1>&6
 cross_compiling=$ac_cv_prog_cxx_cross
 
 echo $ac_n "checking whether we are using GNU C++""... $ac_c" 1>&6
-echo "configure:1156: checking whether we are using GNU C++" >&5
+echo "configure:1159: checking whether we are using GNU C++" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_gxx'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -1161,7 +1164,7 @@ else
   yes;
 #endif
 EOF
-if { ac_try='${CXX-g++} -E conftest.C'; { (eval echo configure:1165: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
+if { ac_try='${CXX-g++} -E conftest.C'; { (eval echo configure:1168: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }; } | egrep yes >/dev/null 2>&1; then
   ac_cv_prog_gxx=yes
 else
   ac_cv_prog_gxx=no
@@ -1180,7 +1183,7 @@ ac_test_CXXFLAGS="${CXXFLAGS+set}"
 ac_save_CXXFLAGS="$CXXFLAGS"
 CXXFLAGS=
 echo $ac_n "checking whether ${CXX-g++} accepts -g""... $ac_c" 1>&6
-echo "configure:1184: checking whether ${CXX-g++} accepts -g" >&5
+echo "configure:1187: checking whether ${CXX-g++} accepts -g" >&5
 if eval "test \"`echo '$''{'ac_cv_prog_cxx_g'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -1221,7 +1224,7 @@ for ac_declaration in \
    'void exit (int);'
 do
   cat > conftest.$ac_ext <<EOF
-#line 1225 "configure"
+#line 1228 "configure"
 #include "confdefs.h"
 #include <stdlib.h>
 $ac_declaration
@@ -1229,7 +1232,7 @@ int main() {
 exit (42);
 ; return 0; }
 EOF
-if { (eval echo configure:1233: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+if { (eval echo configure:1236: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   :
 else
   echo "configure: failed program was:" >&5
@@ -1239,14 +1242,14 @@ else
 fi
 rm -f conftest*
   cat > conftest.$ac_ext <<EOF
-#line 1243 "configure"
+#line 1246 "configure"
 #include "confdefs.h"
 $ac_declaration
 int main() {
 exit (42);
 ; return 0; }
 EOF
-if { (eval echo configure:1250: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+if { (eval echo configure:1253: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   break
 else
@@ -1263,13 +1266,13 @@ fi
 
 
     echo $ac_n "checking for object suffix""... $ac_c" 1>&6
-echo "configure:1267: checking for object suffix" >&5
+echo "configure:1270: checking for object suffix" >&5
 if eval "test \"`echo '$''{'ac_cv_objext'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   rm -f conftest*
 echo 'int i = 1;' > conftest.$ac_ext
-if { (eval echo configure:1273: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+if { (eval echo configure:1276: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   for ac_file in conftest.*; do
     case $ac_file in
     *.c) ;;
@@ -1287,12 +1290,12 @@ OBJEXT=$ac_cv_objext
 ac_objext=$ac_cv_objext
 
     echo $ac_n "checking for Cygwin environment""... $ac_c" 1>&6
-echo "configure:1291: checking for Cygwin environment" >&5
+echo "configure:1294: checking for Cygwin environment" >&5
 if eval "test \"`echo '$''{'ac_cv_cygwin'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1296 "configure"
+#line 1299 "configure"
 #include "confdefs.h"
 
 int main() {
@@ -1303,7 +1306,7 @@ int main() {
 return __CYGWIN__;
 ; return 0; }
 EOF
-if { (eval echo configure:1307: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+if { (eval echo configure:1310: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   ac_cv_cygwin=yes
 else
@@ -1320,19 +1323,19 @@ echo "$ac_t""$ac_cv_cygwin" 1>&6
 CYGWIN=
 test "$ac_cv_cygwin" = yes && CYGWIN=yes
 echo $ac_n "checking for mingw32 environment""... $ac_c" 1>&6
-echo "configure:1324: checking for mingw32 environment" >&5
+echo "configure:1327: checking for mingw32 environment" >&5
 if eval "test \"`echo '$''{'ac_cv_mingw32'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
   cat > conftest.$ac_ext <<EOF
-#line 1329 "configure"
+#line 1332 "configure"
 #include "confdefs.h"
 
 int main() {
 return __MINGW32__;
 ; return 0; }
 EOF
-if { (eval echo configure:1336: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
+if { (eval echo configure:1339: \"$ac_compile\") 1>&5; (eval $ac_compile) 2>&5; }; then
   rm -rf conftest*
   ac_cv_mingw32=yes
 else
@@ -1351,7 +1354,7 @@ test "$ac_cv_mingw32" = yes && MINGW32=y
 
 
 echo $ac_n "checking for executable suffix""... $ac_c" 1>&6
-echo "configure:1355: checking for executable suffix" >&5
+echo "configure:1358: checking for executable suffix" >&5
 if eval "test \"`echo '$''{'ac_cv_exeext'+set}'`\" = set"; then
   echo $ac_n "(cached) $ac_c" 1>&6
 else
@@ -1361,7 +1364,7 @@ else
   rm -f conftest*
   echo 'int main () { return 0; }' > conftest.$ac_ext
   ac_cv_exeext=
-  if { (eval echo configure:1365: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
+  if { (eval echo configure:1368: \"$ac_link\") 1>&5; (eval $ac_link) 2>&5; }; then
     for file in conftest.*; do
       case $file in
       *.c | *.o | *.obj) ;;
@@ -1399,7 +1402,7 @@ ac_exeext=$EXEEXT
     
 
     echo $ac_n "checking "for Visual C++"""... $ac_c" 1>&6
-echo "configure:1403: checking "for Visual C++"" >&5
+echo "configure:1406: checking "for Visual C++"" >&5
     MSVC="no";
     if test "${CC}" = "cl" ; then
        MSVC="yes"
@@ -1438,7 +1441,7 @@ fi
     
 
     echo $ac_n "checking "the default compiler flags"""... $ac_c" 1>&6
-echo "configure:1442: checking "the default compiler flags"" >&5
+echo "configure:1445: checking "the default compiler flags"" >&5
 
             ecosflags_enable_debug="no"
     # Check whether --enable-debug or --disable-debug was given.
@@ -1531,6 +1534,135 @@ fi
     
     
 
+
+            echo $ac_n "checking how to run the C preprocessor""... $ac_c" 1>&6
+echo "configure:1540: checking how to run the C preprocessor" >&5
+# On Suns, sometimes $CPP names a directory.
+if test -n "$CPP" && test -d "$CPP"; then
+  CPP=
+fi
+if test -z "$CPP"; then
+if eval "test \"`echo '$''{'ac_cv_prog_CPP'+set}'`\" = set"; then
+  echo $ac_n "(cached) $ac_c" 1>&6
+else
+    # This must be in double quotes, not single quotes, because CPP may get
+  # substituted into the Makefile and "${CC-cc}" will confuse make.
+  CPP="${CC-cc} -E"
+  # On the NeXT, cc -E runs the code through the compiler's parser,
+  # not just through cpp.
+  cat > conftest.$ac_ext <<EOF
+#line 1555 "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:1561: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out | grep -v "^conftest.${ac_ext}\$"`
+if test -z "$ac_err"; then
+  :
+else
+  echo "$ac_err" >&5
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
+  rm -rf conftest*
+  CPP="${CC-cc} -E -traditional-cpp"
+  cat > conftest.$ac_ext <<EOF
+#line 1572 "configure"
+#include "confdefs.h"
+#include <assert.h>
+Syntax Error
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1578: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out | grep -v "^conftest.${ac_ext}\$"`
+if test -z "$ac_err"; then
+  :
+else
+  echo "$ac_err" >&5
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
+  rm -rf conftest*
+  CPP="${CC-cc} -nologo -E"
+  cat > conftest.$ac_ext <<EOF
+#line 1589 "configure"
+#include "confdefs.h"
+#include <assert.h>
+Syntax Error
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1595: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out | grep -v "^conftest.${ac_ext}\$"`
+if test -z "$ac_err"; then
+  :
+else
+  echo "$ac_err" >&5
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
+  rm -rf conftest*
+  CPP=/lib/cpp
+fi
+rm -f conftest*
+fi
+rm -f conftest*
+fi
+rm -f conftest*
+  ac_cv_prog_CPP="$CPP"
+fi
+  CPP="$ac_cv_prog_CPP"
+else
+  ac_cv_prog_CPP="$CPP"
+fi
+echo "$ac_t""$CPP" 1>&6
+
+for ac_hdr in "linux/if_tun.h"
+do
+ac_safe=`echo "$ac_hdr" | sed 'y%./+-%__p_%'`
+echo $ac_n "checking for $ac_hdr""... $ac_c" 1>&6
+echo "configure:1623: checking for $ac_hdr" >&5
+if eval "test \"`echo '$''{'ac_cv_header_$ac_safe'+set}'`\" = set"; then
+  echo $ac_n "(cached) $ac_c" 1>&6
+else
+  cat > conftest.$ac_ext <<EOF
+#line 1628 "configure"
+#include "confdefs.h"
+#include <$ac_hdr>
+EOF
+ac_try="$ac_cpp conftest.$ac_ext >/dev/null 2>conftest.out"
+{ (eval echo configure:1633: \"$ac_try\") 1>&5; (eval $ac_try) 2>&5; }
+ac_err=`grep -v '^ *+' conftest.out | grep -v "^conftest.${ac_ext}\$"`
+if test -z "$ac_err"; then
+  rm -rf conftest*
+  eval "ac_cv_header_$ac_safe=yes"
+else
+  echo "$ac_err" >&5
+  echo "configure: failed program was:" >&5
+  cat conftest.$ac_ext >&5
+  rm -rf conftest*
+  eval "ac_cv_header_$ac_safe=no"
+fi
+rm -f conftest*
+fi
+if eval "test \"`echo '$ac_cv_header_'$ac_safe`\" = yes"; then
+  echo "$ac_t""yes" 1>&6
+    ac_tr_hdr=HAVE_`echo $ac_hdr | sed 'y%abcdefghijklmnopqrstuvwxyz./-%ABCDEFGHIJKLMNOPQRSTUVWXYZ___%'`
+  cat >> confdefs.h <<EOF
+#define $ac_tr_hdr 1
+EOF
+ TAP_SUPPORTED="yes"
+else
+  echo "$ac_t""no" 1>&6
+TAP_SUPPORTED="no"
+fi
+done
+
+    if test "${TAP_SUPPORTED}" = "no" ; then
+        echo "configure: warning: No <linux/if_tun.h> header, ethertap support disabled." 1>&2
+    fi
+fi
+
+if test "${SUPPORTED}" = "no" ; then
+    echo "configure: warning: The synthetic ethernet support cannot be built on this platform." 1>&2
 fi
 
 
@@ -1724,6 +1856,7 @@ s%@ECOS_REPOSITORY@%$ECOS_REPOSITORY%g
 s%@PACKAGE_DIR@%$PACKAGE_DIR%g
 s%@PACKAGE_VERSION@%$PACKAGE_VERSION%g
 s%@PACKAGE_INSTALL@%$PACKAGE_INSTALL%g
+s%@CPP@%$CPP%g
 s%@SUPPORTED_TRUE@%$SUPPORTED_TRUE%g
 s%@SUPPORTED_FALSE@%$SUPPORTED_FALSE%g
 
--- a/packages/devs/eth/synth/ecosynth/current/host/configure.in
+++ b/packages/devs/eth/synth/ecosynth/current/host/configure.in
@@ -62,6 +62,9 @@ case "${host}" in
     i[[34567]]86-*-linux-gnu* ) SUPPORTED="yes";;
     * ) SUPPORTED="no"
 esac
+if test "${SUPPORTED}" = "no" ; then
+    AC_MSG_WARN([Synthetic target ethernet support is only available on x86 Linux hosts])
+fi   
 
 if test "${SUPPORTED}" = "yes" ; then
     AC_PROG_CC
@@ -71,6 +74,17 @@ if test "${SUPPORTED}" = "yes" ; then
     ECOS_PROG_MSVC
     ECOS_PROG_STANDARD_COMPILER_FLAGS
     ECOS_PACKAGE_DIRS
+
+    dnl Old kernels may not have tun/tap support. rawether can
+    dnl still operate via a spare ethernet interface.
+    AC_CHECK_HEADERS("linux/if_tun.h",TAP_SUPPORTED="yes",TAP_SUPPORTED="no")
+    if test "${TAP_SUPPORTED}" = "no" ; then
+        AC_MSG_WARN([No <linux/if_tun.h> header, ethertap support disabled.])
+    fi
+fi
+
+if test "${SUPPORTED}" = "no" ; then
+    AC_MSG_WARN([The synthetic ethernet support cannot be built on this platform.])
 fi
 
 AM_CONDITIONAL(SUPPORTED, test "${SUPPORTED}" = "yes")
--- a/packages/devs/eth/synth/ecosynth/current/host/rawether.c
+++ b/packages/devs/eth/synth/ecosynth/current/host/rawether.c
@@ -63,7 +63,9 @@
 #include <netinet/if_ether.h>
 #include <linux/if_packet.h>
 #include <linux/if_ether.h>
-#include <linux/if_tun.h>
+#ifdef HAVE_LINUX_IF_TUN_H
+# include <linux/if_tun.h>
+#endif
 
 // The protocol between host and target is defined by a private
 // target-side header.
@@ -98,6 +100,14 @@ static int up = 0;
 static unsigned char tx_buffer[MTU];
 static unsigned char rx_buffer[MTU+4];
 
+// Indirect to get to the actual implementation functions.
+static void (*tx_fn)(unsigned char*, int);
+static void (*rx_fn)(void);
+static void (*start_fn)(int);
+static void (*stop_fn)(void);
+static void (*multicast_fn)(int);
+
+
 // ----------------------------------------------------------------------------
 // A utility buffer for messages.
 #define MSG_SIZE 256
@@ -304,6 +314,12 @@ real_init(char* devname)
 {
     struct sockaddr_ll  addr;
     struct ifreq        request;
+
+    tx_fn           = &real_handle_tx;
+    rx_fn           = &real_handle_rx;
+    start_fn        = &real_handle_start;
+    stop_fn         = &real_handle_stop;
+    multicast_fn    = &real_handle_multiall;
     
     if (strlen(devname) >= IFNAMSIZ) {
         snprintf(msg, MSG_SIZE, "Invalid real network device name \"%s\", too long.\n", devname);
@@ -402,6 +418,10 @@ real_init(char* devname)
 // The Linux kernel will invent a MAC address for its interface. An
 // additional one is needed for eCos. This is either invented or
 // specified in the target definition file.
+//
+// Old Linux kernels may not have the required support. This is detected
+// by an autoconf test for <linux/if_tun.h>
+#ifdef HAVE_LINUX_IF_TUN_H
 
 static void
 tap_handle_tx(unsigned char* buffer, int size)
@@ -500,11 +520,18 @@ tap_handle_multiall(int on)
 {
 }
 
-static void tap_init(int argc, char** argv)
+static void
+tap_init(int argc, char** argv)
 {
     char* devname   = NULL;
     struct ifreq    ifr;
 
+    tx_fn           = &tap_handle_tx;
+    rx_fn           = &tap_handle_rx;
+    start_fn        = &tap_handle_start;
+    stop_fn         = &tap_handle_stop;
+    multicast_fn    = &tap_handle_multiall;
+    
     // Which device? By default let the system pick one, but the user
     // can override this.
     if (0 != argc) {
@@ -561,6 +588,14 @@ static void tap_init(int argc, char** ar
     
     // All done.
 }
+#else
+static void
+tap_init(int argc, char** argv)
+{
+    snprintf(msg, MSG_SIZE, "Ethertap support was not available when the host-side support was built\n");
+    report_error(msg);
+}
+#endif  // HAVE_LINUX_IF_TUN_H
 
 // ----------------------------------------------------------------------------
 // Receive a single request from ecosynth. This consists of a four-byte
@@ -640,40 +675,24 @@ handle_ecosynth_request(void)
                 exit(1);
             }
 
-            if (real_ether) {
-                real_handle_tx(tx_buffer, size);
-            } else if (ethertap) {
-                tap_handle_tx(tx_buffer, size);
-            }
+            (*tx_fn)(tx_buffer, size);
             break;
         }
       case SYNTH_ETH_START:
         {
-            if (real_ether) {
-                real_handle_start(arg);
-            } else if (ethertap) {
-                tap_handle_start(arg);
-            }
+            (*start_fn)(arg);
             break;
         }
 
       case SYNTH_ETH_STOP:
         {
-            if (real_ether) {
-                real_handle_stop();
-            } else if (ethertap) {
-                tap_handle_stop();
-            }
+            (*stop_fn)();
             break;
         }
 
       case SYNTH_ETH_MULTIALL:
         {
-            if (real_ether) {
-                real_handle_multiall(arg);
-            } else if (ethertap) {
-                tap_handle_multiall(arg);
-            }
+            (*multicast_fn)(arg);
             break;
         }
 
@@ -713,11 +732,7 @@ mainloop(void)
         if (FD_ISSET(0, &read_set)) {
             handle_ecosynth_request();
         } else if (FD_ISSET(ether_fd, &read_set)) {
-            if (real_ether) {
-                real_handle_rx();
-            } else {
-                tap_handle_rx();
-            }
+            (*rx_fn)();
         }
     }
 }