Apply by doing:
	cd /usr/src
	patch -p0 < 034_zsconsole.patch

And then rebuild your kernel.

Index: sys/arch/sparc/dev/zs.c
===================================================================
RCS file: /cvs/src/sys/arch/sparc/dev/zs.c,v
retrieving revision 1.22
retrieving revision 1.22.6.1
diff -u -r1.22 -r1.22.6.1
--- sys/arch/sparc/dev/zs.c	1999/09/20 02:49:25	1.22
+++ sys/arch/sparc/dev/zs.c	2000/11/10 20:19:25	1.22.6.1
@@ -948,7 +948,7 @@
 #endif
 		ienab_bis(IE_ZSSOFT);
 	}
-	return (intflags & ZSHARD_WAS_SERVICED);
+	return (intflags & ZSHARD_WAS_SERVICED) ? 1 : -1 /* XXX */;
 }
 
 static int