Hi,
since sun3 has cpu_Debugger()/Debugger() always available
(for !DDB case, it has it's own definition in
sys/arch/sun3/sun3/stub.c),
the most simple way to get the appropriate define & prototype
for !DDB case on sun3 is changing sys/sys/sytm.h as:

Index: systm.h
===================================================================
RCS file: /cvsroot/syssrc/sys/sys/systm.h,v
retrieving revision 1.97
diff -u -p -r1.97 systm.h
--- systm.h     1999/10/14 18:42:16     1.97
+++ systm.h     1999/11/03 14:48:38
@@ -306,9 +306,13 @@ void       kmstartup __P((void));
 #endif

 #ifdef _KERNEL
-#ifdef DDB
+#if defined(DDB) || defined(_SUN3_)
+/* note that cpu_Debugger() is always available on sun3 */
 void   cpu_Debugger __P((void));
 #define Debugger       cpu_Debugger
+#endif
+
+#ifdef DDB
 /*
  * Enter debugger(s) from console attention if enabled
  */

That way, the sun3-specific code would not need to mess with
opt_ddb.h unless really needed, so it would make things a bit
cleaner.

Anyone has any objections to the change ? Or is the defined(_SUN3_)
too ugly ?

Jaromir