--- Net2/vm/vm_pager.c	2018/04/24 18:09:19	1.1.1.2
+++ Net2/vm/vm_pager.c	2018/04/24 18:14:56	1.1.1.3
@@ -33,7 +33,8 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	@(#)vm_pager.c	7.4 (Berkeley) 5/7/91
+ *	from: @(#)vm_pager.c	7.4 (Berkeley) 5/7/91
+ *	vm_pager.c,v 1.4.2.1 1993/07/24 21:34:02 cgd Exp
  *
  *
  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
@@ -60,13 +61,6 @@
  *
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
- *
- * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
- * --------------------         -----   ----------------------
- * CURRENT PATCH LEVEL:         1       00063
- * --------------------         -----   ----------------------
- *
- * 28 Nov 1991	Poul-Henning Kamp	Speedup processing
  */
 
 /*
@@ -82,29 +76,34 @@
 #include "vm_kern.h"
 
 #include "swappager.h"
-
 #if NSWAPPAGER > 0
 extern struct pagerops swappagerops;
-#else
-#define	swappagerops	NULL
 #endif
 #include "vnodepager.h"
 #if NVNODEPAGER > 0
 extern struct pagerops vnodepagerops;
-#else
-#define	vnodepagerops	NULL
 #endif
 #include "devpager.h"
 #if NDEVPAGER > 0
 extern struct pagerops devicepagerops;
-#else
-#define	devicepagerops	NULL
 #endif
 
 struct pagerops *pagertab[] = {
+#if NSWAPPAGER > 0
 	&swappagerops,		/* PG_SWAP */
+#else
+	NULL,			/* no swappager */
+#endif
+#if NVNODEPAGER > 0
 	&vnodepagerops,		/* PG_VNODE */
+#else
+	NULL,			/* no vnodepager */
+#endif
+#if NDEVPAGER > 0
 	&devicepagerops,	/* PG_DEV */
+#else
+	NULL,			/* no devpager */
+#endif
 };
 int npagers = sizeof (pagertab) / sizeof (pagertab[0]);
 
@@ -132,7 +131,7 @@ vm_pager_init()
 	 * Initialize known pagers
 	 */
 	for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++)
-		(*(*pgops)->pgo_init)();
+		if (*pgops) (*(*pgops)->pgo_init)();
 	if (dfltpagerops == NULL)
 		panic("no default pager");
 }
@@ -206,7 +205,7 @@ vm_pager_sync()
 	struct pagerops **pgops;
 
 	for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++)
-		(*(*pgops)->pgo_putpage)(NULL, NULL, FALSE);
+		if (*pgops) (*(*pgops)->pgo_putpage)(NULL, NULL, FALSE);
 }
 
 vm_offset_t