Index: kern/kern_sysctl.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_sysctl.c,v
retrieving revision 1.136
diff -u -r1.136 kern_sysctl.c
--- kern/kern_sysctl.c	28 Nov 2005 00:14:29 -0000	1.136
+++ kern/kern_sysctl.c	10 Feb 2006 14:43:45 -0000
@@ -241,6 +241,8 @@
 int securelevel;
 #endif
 
+int boottime_adj;
+
 /*
  * kernel related system variables.
  */
@@ -344,8 +346,17 @@
 	case KERN_CLOCKRATE:
 		return (sysctl_clockrate(oldp, oldlenp));
 	case KERN_BOOTTIME:
-		return (sysctl_rdstruct(oldp, oldlenp, newp, &boottime,
-		    sizeof(struct timeval)));
+		{
+			struct timeval tv;
+
+			tv = boottime;
+			tv.tv_sec += boottime_adj;
+
+			return (sysctl_rdstruct(oldp, oldlenp, newp, &tv,
+			    sizeof(struct timeval)));
+		}
+	case KERN_BOOTTIMEADJ:
+		return (sysctl_int(oldp, oldlenp, newp, newlen, &boottime_adj));
 	case KERN_VNODE:
 		return (sysctl_vnode(oldp, oldlenp, p));
 #ifndef SMALL_KERNEL
Index: sys/sysctl.h
===================================================================
RCS file: /cvs/src/sys/sys/sysctl.h,v
retrieving revision 1.85
diff -u -r1.85 sysctl.h
--- sys/sysctl.h	13 Dec 2005 00:35:23 -0000	1.85
+++ sys/sysctl.h	10 Feb 2006 14:43:46 -0000
@@ -184,7 +184,8 @@
 #define	KERN_TIMECOUNTER	69	/* node: timecounter */
 #define	KERN_MAXLOCKSPERUID	70	/* int: locks per uid */
 #define	KERN_CPTIME2		71	/* array: cp_time2 */
-#define	KERN_MAXID		72	/* number of valid kern ids */
+#define KERN_BOOTTIMEADJ	72	/* int: boottime adjustment. */
+#define	KERN_MAXID		73	/* number of valid kern ids */
 
 #define	CTL_KERN_NAMES { \
 	{ 0, 0 }, \
@@ -259,6 +260,7 @@
  	{ "timecounter", CTLTYPE_NODE }, \
  	{ "maxlocksperuid", CTLTYPE_INT }, \
  	{ "cp_time2", CTLTYPE_STRUCT }, \
+	{ "boottime_adj", CTLTYPE_INT }, \
 }
 
 /*