diff --git a/sys/kern/kern_shutdown.c b/sys/kern/kern_shutdown.c
index 1353dbf66573..c34e8752cba0 100644
--- a/sys/kern/kern_shutdown.c
+++ b/sys/kern/kern_shutdown.c
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)kern_shutdown.c	8.3 (Berkeley) 1/21/94
- * $Id: kern_shutdown.c,v 1.16 1997/06/15 02:03:03 wollman Exp $
+ * $Id: kern_shutdown.c,v 1.17 1997/06/22 16:04:16 peter Exp $
  */
 
 #include "opt_ddb.h"
@@ -90,6 +90,15 @@ SYSCTL_INT(_debug, OID_AUTO, debugger_on_panic, CTLFLAG_RW,
 #endif
 
 
+/*
+ * If there is a hardware watchdog, point this at the function needed to
+ * hold it off.
+ * It's needed when the kernel needs to do some lengthy operations.
+ * e.g. in wd.c when dumping core.. It's most annoying to have
+ * your precious core-dump only half written because the wdog kicked in.
+ */
+watchdog_tickle_fn wdog_tickler = NULL;
+
 /*
  * Variable panicstr contains argument to first call to panic; used as flag
  * to indicate that the kernel has already called panic.
@@ -190,12 +199,19 @@ boot(howto)
 		}
 	}
 #endif
+	/*
+	 * Do any callouts that should be done BEFORE syncing the filesystems.
+	 */
 	ep = shutdown_list1;
 	while (ep) {
 		shutdown_list1 = ep->next;
 		(*ep->function)(howto, ep->arg);
 		ep = ep->next;
 	}
+
+	/* 
+	 * Now sync filesystems
+	 */
 	if (!cold && (howto & RB_NOSYNC) == 0 && waittime < 0) {
 		register struct buf *bp;
 		int iter, nbusy;
@@ -243,6 +259,11 @@ boot(howto)
 		}
 		DELAY(100000);			/* wait for console output to finish */
 	}
+
+	/*
+	 * Ok, now do things that assume all filesystem activity has
+	 * been completed.
+	 */
 	ep = shutdown_list2;
 	while (ep) {
 		shutdown_list2 = ep->next;
diff --git a/sys/sys/systm.h b/sys/sys/systm.h
index 44dd7136f078..6ffabe2c5997 100644
--- a/sys/sys/systm.h
+++ b/sys/sys/systm.h
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)systm.h	8.7 (Berkeley) 3/29/95
- * $Id: systm.h,v 1.53 1997/07/21 16:43:48 bde Exp $
+ * $Id: systm.h,v 1.54 1997/08/09 00:04:06 dyson Exp $
  */
 
 #ifndef _SYS_SYSTM_H_
@@ -223,6 +223,16 @@ typedef void (*exitlist_fn)(struct proc *procp);
 int at_exit(exitlist_fn function);
 int rm_at_exit(exitlist_fn function);
 
+/* Not exactly a callout LIST, but a callout entry.. 			*/
+/* Allow an external module to define a hardware watchdog tickler	*/
+/* Normally a process would do this, but there are times when the	*/
+/* kernel needs to be able to hold off the watchdog, when the process	*/
+/* is not active, e.g. when dumping core. Costs us a whole 4 bytes to	*/
+/* make this generic. the variable is in kern_shutdown.c */
+typedef void (*watchdog_tickle_fn)(void);
+extern watchdog_tickle_fn wdog_tickler;
+
+
 /* 
  * Common `proc' functions are declared here so that proc.h can be included
  * less often.