--- SheepShaver/src/Unix/configure.in	2004/04/13 22:13:19	1.23
+++ SheepShaver/src/Unix/configure.in	2004/06/22 22:41:44	1.25
@@ -183,6 +183,7 @@ AC_HEADER_SYS_WAIT
 AC_CHECK_HEADERS(mach/vm_map.h mach/mach_init.h sys/mman.h)
 AC_CHECK_HEADERS(sys/time.h sys/times.h)
 AC_CHECK_HEADERS(unistd.h fcntl.h byteswap.h)
+AC_CHECK_HEADERS(linux/if.h linux/if_tun.h net/if.h net/if_tun.h)
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 AC_C_BIGENDIAN
@@ -273,6 +274,29 @@ AC_DEFUN(AC_TRANSLATE_DEFINE, [
     fi
 ])
 
+dnl Check that the host supports TUN/TAP devices
+AC_CACHE_CHECK([whether TUN/TAP is supported],
+  ac_cv_tun_tap_support, [
+  AC_TRY_COMPILE([
+    #if defined(HAVE_LINUX_IF_H) && defined(HAVE_LINUX_IF_TUN_H)
+    #include <linux/if.h>
+    #include <linux/if_tun.h>
+    #endif
+    #if defined(HAVE_NET_IF_H) && defined(HAVE_NET_IF_TUN_H)
+    #include <net/if.h>
+    #include <net/if_tun.h>
+    #endif
+  ], [
+    struct ifreq ifr;
+    memset(&ifr, 0, sizeof(ifr));
+    ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+  ],
+  ac_cv_tun_tap_support=yes, ac_cv_tun_tap_support=no
+  )
+])
+AC_TRANSLATE_DEFINE(ENABLE_TUNTAP, "$ac_cv_tun_tap_support",
+  [Define if your system supports TUN/TAP devices.])
+
 dnl Various checks if the system supports vm_allocate() and the like functions.
 have_mach_vm=no
 if [[ "x$ac_cv_func_vm_allocate" = "xyes" -a "x$ac_cv_func_vm_deallocate" = "xyes" -a \
@@ -618,6 +642,14 @@ dnl Can we do Video on SEGV Signals ?
 CAN_VOSF=no
 if [[ -n "$sigsegv_recovery" ]]; then
   CAN_VOSF=yes
+  case $target_os in
+  darwin*)
+    dnl Signal handlers in darwin are way too slow since the whole
+    dnl machine state (GPRs, FPRs, VRs) is forcibly saved.
+    dnl In other words, VOSF is slower than static window refreshes.
+    CAN_VOSF=no
+    ;;
+  esac
 fi
 
 dnl Enable VOSF screen updates with this feature is requested and feasible