Mark the current ISDN4Linux link layer obsolete

drivers/isdn/Config.help

-CONFIG_ISDN
+CONFIG_ISDN_BOOL
   ISDN ("Integrated Services Digital Networks", called RNIS in France)
   is a special type of fully digital telephone service; it's mostly
   used to connect to your Internet service provider (with SLIP or
@@ -9,6 +9,9 @@ CONFIG_ISDN
   provider purchased an ISDN line from the phone company.  For
   details, read <http://alumni.caltech.edu/~dank/isdn/> on the WWW.
 
+  Select this option if you want your kernel to support ISDN.
+
+CONFIG_ISDN
   This driver allows you to use an ISDN-card for networking
   connections and as dialin/out device.  The isdn-tty's have a built
   in AT-compatible modem emulator.  Network devices support autodial,
@@ -18,6 +21,11 @@ CONFIG_ISDN
   (Euro-ISDN) and 1TR6 (German style) are supported.  See
   <file:Documentation/isdn/README> for more information.
 
+  ISDN support in the linux kernel is moving towards a new API,
+  called CAPI (Common ISDN Application Programming Interface).
+  Therefore the old ISDN4Linux layer is becoming obsolete. It is 
+  still usable, though, if you select this option.
+
   If you want to compile the ISDN code as a module ( = code which can
   be inserted in and removed from the running kernel whenever you
   want), say M here and read <file:Documentation/modules.txt>.  The

drivers/isdn/Config.in

@@ -5,7 +5,13 @@
 mainmenu_option next_comment
 comment 'ISDN subsystem'
 if [ "$CONFIG_NET" != "n" ]; then
-   tristate 'ISDN support' CONFIG_ISDN
+   bool 'ISDN support' CONFIG_ISDN_BOOL
+
+   if [ "$CONFIG_ISDN_BOOL" == "y" ]; then
+      mainmenu_option next_comment
+      comment 'Old ISDN4Linux'
+
+      dep_tristate 'Old ISDN4Linux (obsolete)' CONFIG_ISDN
       if [ "$CONFIG_ISDN" != "n" ]; then
 
 ### CONFIG_ISDN is set  #####################################################
@@ -162,6 +168,8 @@ endmenu
 ### CONFIG_ISDN end #########################################################
 
       fi
+      endmenu
+   fi
 fi
 endmenu