diff --git a/lib/libkvm/kvm_proc.c b/lib/libkvm/kvm_proc.c
index 31258d7a09be..aed61a854919 100644
--- a/lib/libkvm/kvm_proc.c
+++ b/lib/libkvm/kvm_proc.c
@@ -431,6 +431,24 @@ kvm_proclist(kvm_t *kd, int what, int arg, struct proc *p,
 				strlcpy(kp->ki_tdname, mtd.td_name, sizeof(kp->ki_tdname));
 			kp->ki_pctcpu = 0;
 			kp->ki_rqindex = 0;
+
+			/*
+			 * Note: legacy fields; wraps at NO_CPU_OLD or the
+			 * old max CPU value as appropriate
+			 */
+			if (mtd.td_lastcpu == NOCPU)
+				kp->ki_lastcpu_old = NOCPU_OLD;
+			else if (mtd.td_lastcpu > MAXCPU_OLD)
+				kp->ki_lastcpu_old = MAXCPU_OLD;
+			else
+				kp->ki_lastcpu_old = mtd.td_lastcpu;
+
+			if (mtd.td_oncpu == NOCPU)
+				kp->ki_oncpu_old = NOCPU_OLD;
+			else if (mtd.td_oncpu > MAXCPU_OLD)
+				kp->ki_oncpu_old = MAXCPU_OLD;
+			else
+				kp->ki_oncpu_old = mtd.td_oncpu;
 		} else {
 			kp->ki_stat = SZOMB;
 		}
diff --git a/sys/compat/freebsd32/freebsd32.h b/sys/compat/freebsd32/freebsd32.h
index 155612ba342f..af10055d0936 100644
--- a/sys/compat/freebsd32/freebsd32.h
+++ b/sys/compat/freebsd32/freebsd32.h
@@ -332,8 +332,8 @@ struct kinfo_proc32 {
 	signed char ki_nice;
 	char	ki_lock;
 	char	ki_rqindex;
-	u_char	ki_oncpu;
-	u_char	ki_lastcpu;
+	u_char	ki_oncpu_old;
+	u_char	ki_lastcpu_old;
 	char	ki_tdname[TDNAMLEN+1];
 	char	ki_wmesg[WMESGLEN+1];
 	char	ki_login[LOGNAMELEN+1];
@@ -343,6 +343,8 @@ struct kinfo_proc32 {
 	char	ki_loginclass[LOGINCLASSLEN+1];
 	char	ki_sparestrings[50];
 	int	ki_spareints[KI_NSPARE_INT];
+	int	ki_oncpu;
+	int	ki_lastcpu;
 	int	ki_tracer;
 	int	ki_flag2;
 	int	ki_fibnum;
diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index 41cd3043bf44..495139fa368d 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -984,6 +984,25 @@ fill_kinfo_thread(struct thread *td, struct kinfo_proc *kp, int preferthread)
 	kp->ki_wchan = td->td_wchan;
 	kp->ki_pri.pri_level = td->td_priority;
 	kp->ki_pri.pri_native = td->td_base_pri;
+
+	/*
+	 * Note: legacy fields; clamp at the old NOCPU value and/or
+	 * the maximum u_char CPU value.
+	 */
+	if (td->td_lastcpu == NOCPU)
+		kp->ki_lastcpu_old = NOCPU_OLD;
+	else if (td->td_lastcpu > MAXCPU_OLD)
+		kp->ki_lastcpu_old = MAXCPU_OLD;
+	else
+		kp->ki_lastcpu_old = td->td_lastcpu;
+
+	if (td->td_oncpu == NOCPU)
+		kp->ki_oncpu_old = NOCPU_OLD;
+	else if (td->td_oncpu > MAXCPU_OLD)
+		kp->ki_oncpu_old = MAXCPU_OLD;
+	else
+		kp->ki_oncpu_old = td->td_oncpu;
+
 	kp->ki_lastcpu = td->td_lastcpu;
 	kp->ki_oncpu = td->td_oncpu;
 	kp->ki_tdflags = td->td_flags;
@@ -1164,6 +1183,11 @@ freebsd32_kinfo_proc_out(const struct kinfo_proc *ki, struct kinfo_proc32 *ki32)
 	CP(*ki, *ki32, ki_rqindex);
 	CP(*ki, *ki32, ki_oncpu);
 	CP(*ki, *ki32, ki_lastcpu);
+
+	/* XXX TODO: wrap cpu value as appropriate */
+	CP(*ki, *ki32, ki_oncpu_old);
+	CP(*ki, *ki32, ki_lastcpu_old);
+
 	bcopy(ki->ki_tdname, ki32->ki_tdname, TDNAMLEN + 1);
 	bcopy(ki->ki_wmesg, ki32->ki_wmesg, WMESGLEN + 1);
 	bcopy(ki->ki_login, ki32->ki_login, LOGNAMELEN + 1);
diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c
index 473e334e64a9..0e98fc81414f 100644
--- a/sys/kern/sched_ule.c
+++ b/sys/kern/sched_ule.c
@@ -90,7 +90,7 @@ dtrace_vtime_switch_func_t	dtrace_vtime_switch_func;
 struct td_sched {	
 	struct runq	*ts_runq;	/* Run-queue we're queued on. */
 	short		ts_flags;	/* TSF_* flags. */
-	u_char		ts_cpu;		/* CPU that we have affinity for. */
+	int		ts_cpu;		/* CPU that we have affinity for. */
 	int		ts_rltick;	/* Real last tick, for affinity. */
 	int		ts_slice;	/* Ticks of slice remaining. */
 	u_int		ts_slptime;	/* Number of ticks we vol. slept */
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index 72b2a9f8ca68..fac0915f005c 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -229,8 +229,8 @@ struct thread {
 	int		td_sqqueue;	/* (t) Sleepqueue queue blocked on. */
 	void		*td_wchan;	/* (t) Sleep address. */
 	const char	*td_wmesg;	/* (t) Reason for sleep. */
-	u_char		td_lastcpu;	/* (t) Last cpu we were on. */
-	u_char		td_oncpu;	/* (t) Which cpu we are on. */
+	int		td_lastcpu;	/* (t) Last cpu we were on. */
+	int		td_oncpu;	/* (t) Which cpu we are on. */
 	volatile u_char td_owepreempt;  /* (k*) Preempt on last critical_exit */
 	u_char		td_tsqueue;	/* (t) Turnstile queue blocked on. */
 	short		td_locks;	/* (k) Count of non-spin locks. */
@@ -601,7 +601,9 @@ struct proc {
 #define	p_session	p_pgrp->pg_session
 #define	p_pgid		p_pgrp->pg_id
 
-#define	NOCPU	0xff		/* For when we aren't on a CPU. */
+#define	NOCPU		(-1)	/* For when we aren't on a CPU. */
+#define	NOCPU_OLD	(255)
+#define	MAXCPU_OLD	(254)
 
 #define	PROC_SLOCK(p)	mtx_lock_spin(&(p)->p_slock)
 #define	PROC_SUNLOCK(p)	mtx_unlock_spin(&(p)->p_slock)
diff --git a/sys/sys/user.h b/sys/sys/user.h
index 6775ff7dbcb0..f0d059e0138d 100644
--- a/sys/sys/user.h
+++ b/sys/sys/user.h
@@ -84,7 +84,7 @@
  * it in two places: function fill_kinfo_proc in sys/kern/kern_proc.c and
  * function kvm_proclist in lib/libkvm/kvm_proc.c .
  */
-#define	KI_NSPARE_INT	6
+#define	KI_NSPARE_INT	4
 #define	KI_NSPARE_LONG	12
 #define	KI_NSPARE_PTR	6
 
@@ -171,8 +171,8 @@ struct kinfo_proc {
 	signed char ki_nice;		/* Process "nice" value */
 	char	ki_lock;		/* Process lock (prevent swap) count */
 	char	ki_rqindex;		/* Run queue index */
-	u_char	ki_oncpu;		/* Which cpu we are on */
-	u_char	ki_lastcpu;		/* Last cpu we were on */
+	u_char	ki_oncpu_old;		/* Which cpu we are on (legacy) */
+	u_char	ki_lastcpu_old;		/* Last cpu we were on (legacy) */
 	char	ki_tdname[TDNAMLEN+1];	/* thread name */
 	char	ki_wmesg[WMESGLEN+1];	/* wchan message */
 	char	ki_login[LOGNAMELEN+1];	/* setlogin name */
@@ -187,6 +187,8 @@ struct kinfo_proc {
 	 */
 	char	ki_sparestrings[50];	/* spare string space */
 	int	ki_spareints[KI_NSPARE_INT];	/* spare room for growth */
+	int	ki_oncpu;		/* Which cpu we are on */
+	int	ki_lastcpu;		/* Last cpu we were on */
 	int	ki_tracer;		/* Pid of tracing process */
 	int	ki_flag2;		/* P2_* flags */
 	int	ki_fibnum;		/* Default FIB number */