Index: lib/libc/sys/reboot.2
===================================================================
--- lib/libc/sys/reboot.2
+++ lib/libc/sys/reboot.2
@@ -28,7 +28,7 @@
 .\"     @(#)reboot.2	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd September 18, 2015
+.Dd October 24, 2017
 .Dt REBOOT 2
 .Os
 .Sh NAME
@@ -84,6 +84,11 @@
 .It Dv RB_HALT
 The processor is simply halted; no reboot takes place.
 This option should be used with caution.
+.It Dv RB_POWERCYCLE
+After halting, the shutdown code will do what it can to turn
+off the power and then turn the power back on.
+This requires hardware support, usually an auxiliary microprocessor
+that can sequence the power supply.
 .It Dv RB_POWEROFF
 After halting, the shutdown code will do what it can to turn
 off the power.
Index: sbin/init/init.8
===================================================================
--- sbin/init/init.8
+++ sbin/init/init.8
@@ -286,6 +286,7 @@
 .It Sy "Run-level	Signal	Action"
 .It Cm 0 Ta Dv SIGUSR1 Ta "Halt"
 .It Cm 0 Ta Dv SIGUSR2 Ta "Halt and turn the power off"
+.It Cm 0 Ta Dv SIGWINCH Ta "Halt and turn the power off and then back on"
 .It Cm 1 Ta Dv SIGTERM Ta "Go to single-user mode"
 .It Cm 6 Ta Dv SIGINT Ta "Reboot the machine"
 .It Cm c Ta Dv SIGTSTP Ta "Block further logins"
Index: sbin/init/init.c
===================================================================
--- sbin/init/init.c
+++ sbin/init/init.c
@@ -305,12 +305,12 @@
 	handle(disaster, SIGABRT, SIGFPE, SIGILL, SIGSEGV, SIGBUS, SIGXCPU,
 	    SIGXFSZ, 0);
 	handle(transition_handler, SIGHUP, SIGINT, SIGEMT, SIGTERM, SIGTSTP,
-	    SIGUSR1, SIGUSR2, 0);
+	    SIGUSR1, SIGUSR2, SIGWINCH, 0);
 	handle(alrm_handler, SIGALRM, 0);
 	sigfillset(&mask);
 	delset(&mask, SIGABRT, SIGFPE, SIGILL, SIGSEGV, SIGBUS, SIGSYS,
 	    SIGXCPU, SIGXFSZ, SIGHUP, SIGINT, SIGEMT, SIGTERM, SIGTSTP,
-	    SIGALRM, SIGUSR1, SIGUSR2, 0);
+	    SIGALRM, SIGUSR1, SIGUSR2, SIGWINCH, 0);
 	sigprocmask(SIG_SETMASK, &mask, (sigset_t *) 0);
 	sigemptyset(&sa.sa_mask);
 	sa.sa_flags = 0;
@@ -1557,8 +1557,9 @@
 		    current_state == clean_ttys || current_state == catatonia)
 			requested_transition = clean_ttys;
 		break;
+	case SIGWINCH:
 	case SIGUSR2:
-		howto = RB_POWEROFF;
+		howto = sig == SIGUSR2 ? RB_POWEROFF : RB_POWERCYCLE;
 	case SIGUSR1:
 		howto |= RB_HALT;
 	case SIGINT:
Index: sbin/reboot/reboot.8
===================================================================
--- sbin/reboot/reboot.8
+++ sbin/reboot/reboot.8
@@ -28,7 +28,7 @@
 .\"	@(#)reboot.8	8.1 (Berkeley) 6/9/93
 .\" $FreeBSD$
 .\"
-.Dd March 19, 2017
+.Dd October 23, 2017
 .Dt REBOOT 8
 .Os
 .Sh NAME
@@ -42,7 +42,7 @@
 .Op Fl lNnpq
 .Op Fl k Ar kernel
 .Nm
-.Op Fl dlNnpqr
+.Op Fl cdlNnpqr
 .Op Fl k Ar kernel
 .Nm fasthalt
 .Op Fl lNnpq
@@ -66,6 +66,14 @@
 .Pp
 The options are as follows:
 .Bl -tag -width indent
+.It Fl c
+The system will turn off the power and then turn it back on if it can.
+If the power down action fails, the system
+will halt or reboot normally, depending on whether
+.Nm halt
+or
+.Nm
+was called.
 .It Fl d
 The system is requested to create a crash dump.
 This option is
Index: sbin/reboot/reboot.c
===================================================================
--- sbin/reboot/reboot.c
+++ sbin/reboot/reboot.c
@@ -77,8 +77,11 @@
 	} else
 		howto = 0;
 	lflag = nflag = qflag = Nflag = 0;
-	while ((ch = getopt(argc, argv, "dk:lNnpqr")) != -1)
+	while ((ch = getopt(argc, argv, "cdk:lNnpqr")) != -1)
 		switch(ch) {
+		case 'c':
+			howto |= RB_POWERCYCLE;
+			break;
 		case 'd':
 			howto |= RB_DUMP;
 			break;
@@ -117,7 +120,7 @@
 	if (Nflag && (howto & RB_NOSYNC) != 0)
 		errx(1, "-N cannot be used with -n");
 	if ((howto & RB_REROOT) != 0 && howto != RB_REROOT)
-		errx(1, "-r cannot be used with -d, -n, or -p");
+		errx(1, "-r cannot be used with -c, -d, -n, or -p");
 	if (geteuid()) {
 		errno = EPERM;
 		err(1, NULL);
@@ -151,6 +154,12 @@
 		} else if (howto & RB_REROOT) {
 			openlog("reroot", 0, LOG_AUTH | LOG_CONS);
 			syslog(LOG_CRIT, "rerooted by %s", user);
+		} else if (howto & RB_POWEROFF) {
+			openlog("reboot", 0, LOG_AUTH | LOG_CONS);
+			syslog(LOG_CRIT, "powered off by %s", user);
+		} else if (howto & RB_POWERCYCLE) {
+			openlog("reboot", 0, LOG_AUTH | LOG_CONS);
+			syslog(LOG_CRIT, "power cycled by %s", user);
 		} else {
 			openlog("reboot", 0, LOG_AUTH | LOG_CONS);
 			syslog(LOG_CRIT, "rebooted by %s", user);
Index: sbin/shutdown/shutdown.8
===================================================================
--- sbin/shutdown/shutdown.8
+++ sbin/shutdown/shutdown.8
@@ -28,7 +28,7 @@
 .\"     @(#)shutdown.8	8.2 (Berkeley) 4/27/95
 .\" $FreeBSD$
 .\"
-.Dd September 21, 2016
+.Dd October 23, 2017
 .Dt SHUTDOWN 8
 .Os
 .Sh NAME
@@ -39,7 +39,7 @@
 .Nm
 .Op Fl
 .Oo
-.Fl h | Fl p |
+.Fl c | Fl h | Fl p |
 .Fl r | Fl k
 .Oc
 .Oo
@@ -59,12 +59,18 @@
 .Pp
 The following options are available:
 .Bl -tag -width indent
+.It Fl c
+The system is power cycled (power turned off and then back on)
+at the specified time.
+If the hardware doesn't support power cycle, the system is rebooted if
+the hardware supports that.
+Otherwise the system is halted.
 .It Fl h
 The system is halted at the specified
 .Ar time .
 .It Fl p
 The system is halted and the power is turned off
-(hardware support required)
+(hardware support required, otherwise the system is halted)
 at the specified
 .Ar time .
 .It Fl r
@@ -79,6 +85,7 @@
 system multi-user with logins disabled (for all but super-user).
 .It Fl o
 If one of the
+.Fl c ,
 .Fl h ,
 .Fl p
 or
Index: sbin/shutdown/shutdown.c
===================================================================
--- sbin/shutdown/shutdown.c
+++ sbin/shutdown/shutdown.c
@@ -89,7 +89,7 @@
 #undef S
 
 static time_t offset, shuttime;
-static int dohalt, dopower, doreboot, killflg, mbuflen, oflag;
+static int docycle, dohalt, dopower, doreboot, killflg, mbuflen, oflag;
 static char mbuf[BUFSIZ];
 static const char *nosync, *whom;
 
@@ -141,11 +141,14 @@
 		goto poweroff;
 	}
 
-	while ((ch = getopt(argc, argv, "-hknopr")) != -1)
+	while ((ch = getopt(argc, argv, "-chknopr")) != -1)
 		switch (ch) {
 		case '-':
 			readstdin = 1;
 			break;
+		case 'c':
+			docycle = 1;
+			break;
 		case 'h':
 			dohalt = 1;
 			break;
@@ -174,11 +177,11 @@
 	if (argc < 1)
 		usage((char *)NULL);
 
-	if (killflg + doreboot + dohalt + dopower > 1)
-		usage("incompatible switches -h, -k, -p and -r");
+	if (killflg + doreboot + dohalt + dopower + docycle > 1)
+		usage("incompatible switches -c, -h, -k, -p and -r");
 
-	if (oflag && !(dohalt || dopower || doreboot))
-		usage("-o requires -h, -p or -r");
+	if (oflag && !(dohalt || dopower || doreboot || docycle))
+		usage("-o requires -c, -h, -p or -r");
 
 	if (nosync != NULL && !oflag)
 		usage("-n requires -o");
@@ -356,8 +359,8 @@
 	char *empty_environ[] = { NULL };
 
 	syslog(LOG_NOTICE, "%s by %s: %s",
-	    doreboot ? "reboot" : dohalt ? "halt" : dopower ? "power-down" : 
-	    "shutdown", whom, mbuf);
+	    doreboot ? "reboot" : dohalt ? "halt" : dopower ? "power-down" :
+	    docycle ? "power-cycle" : "shutdown", whom, mbuf);
 
 	(void)printf("\r\nSystem shutdown time has arrived\007\007\r\n");
 	if (killflg) {
@@ -367,6 +370,8 @@
 #ifdef DEBUG
 	if (doreboot)
 		(void)printf("reboot");
+	else if (docycle)
+		(void)printf("power-cycle");
 	else if (dohalt)
 		(void)printf("halt");
 	else if (dopower)
@@ -379,6 +384,7 @@
 		(void)kill(1, doreboot ? SIGINT :	/* reboot */
 			      dohalt ? SIGUSR1 :	/* halt */
 			      dopower ? SIGUSR2 :	/* power-down */
+			      docycle ? SIGWINCH :	/* power-cycle */
 			      SIGTERM);			/* single-user */
 	} else {
 		if (doreboot) {
@@ -402,6 +408,13 @@
 				_PATH_HALT);
 			warn(_PATH_HALT);
 		}
+		else if (docycle) {
+			execle(_PATH_HALT, "halt", "-l", "-c", nosync,
+				(char *)NULL, empty_environ);
+			syslog(LOG_ERR, "shutdown: can't exec %s: %m.",
+				_PATH_HALT);
+			warn(_PATH_HALT);
+		}
 		(void)kill(1, SIGTERM);		/* to single-user */
 	}
 #endif
Index: sys/cam/ata/ata_da.c
===================================================================
--- sys/cam/ata/ata_da.c
+++ sys/cam/ata/ata_da.c
@@ -3513,7 +3513,7 @@
 
 	adaflush();
 	if (ada_spindown_shutdown != 0 &&
-	    (howto & (RB_HALT | RB_POWEROFF)) != 0)
+	    (howto & (RB_HALT | RB_POWEROFF | RB_POWERCYCLE)) != 0)
 		adaspindown(ATA_STANDBY_IMMEDIATE, 0);
 }
 
Index: sys/dev/ipmi/ipmi.c
===================================================================
--- sys/dev/ipmi/ipmi.c
+++ sys/dev/ipmi/ipmi.c
@@ -689,6 +689,45 @@
 	}
 }
 
+static void
+ipmi_power_cycle(void *arg, int howto)
+{
+	struct ipmi_softc *sc = arg;
+	struct ipmi_request *req = &sc->ipmi_req;
+
+	/*
+	 * Ignore everything except power cycling requests
+	 */
+	if ((howto & RB_POWERCYCLE) == 0)
+		return;
+
+	printf("Power cycling using IPMI\n");
+
+	/*
+	 * Send a CHASSIS_CONTROL command to the CHASSIS device, subcommand 2
+	 * as described in IPMI v2.0 spec section 28.3.
+	 */
+	IPMI_INIT_DRIVER_REQUEST(req, IPMI_ADDR(IPMI_CHASSIS_REQUEST, 0),
+	    IPMI_CHASSIS_CONTROL, 1, 0);
+	req->ir_request[0] = IPMI_CC_POWER_CYCLE;
+
+	ipmi_submit_driver_request(sc, req);
+
+	if (req->ir_error != 0 || req->ir_compcode != 0) {
+		printf("Power cycling via IPMI failed code %#x %#x\n",
+		    req->ir_error, req->ir_compcode);
+		return;
+	}
+
+	/*
+	 * BMCs are notoriously slow, give it up to 10s to effect the power
+	 * down leg of the power cycle. If that fails, fallback to the next
+	 * hanlder in the shutdown_final chain and/or the platform failsafe.
+	 */
+	DELAY(10 * 1000 * 1000);
+	printf("Power cycling via IPMI timed out\n");
+}
+
 static void
 ipmi_startup(void *arg)
 {
@@ -742,6 +781,8 @@
 	     req->ir_reply[2] & 0x7f, req->ir_reply[3] >> 4, req->ir_reply[3] & 0x0f,
 	     req->ir_reply[4] & 0x0f, req->ir_reply[4] >> 4);
 
+	sc->ipmi_dev_support = req->ir_reply[5];
+
 	IPMI_INIT_DRIVER_REQUEST(req, IPMI_ADDR(IPMI_APP_REQUEST, 0),
 	    IPMI_CLEAR_FLAGS, 1, 0);
 
@@ -792,6 +833,16 @@
 		return;
 	}
 	sc->ipmi_cdev->si_drv1 = sc;
+
+	/*
+	 * Power cycle the system off using IPMI. We use last - 1 since we don't
+	 * handle all the other kinds of reboots. We'll let others handle them.
+	 * We only try to do this if the BMC supports the Chassis device.
+	 */
+	if (sc->ipmi_dev_support & IPMI_ADS_CHASSIS)
+		sc->ipmi_power_cycle_tag = EVENTHANDLER_REGISTER(shutdown_final,
+		    ipmi_power_cycle, sc, SHUTDOWN_PRI_LAST - 1);
+
 }
 
 int
@@ -844,6 +895,10 @@
 		ipmi_set_watchdog(sc, 0);
 	}
 
+	/* Detach from watchdog handling and turn off watchdog. */
+	if (sc->ipmi_power_cycle_tag)
+		EVENTHANDLER_DEREGISTER(shutdown_final, sc->ipmi_power_cycle_tag);
+
 	/* XXX: should use shutdown callout I think. */
 	/* If the backend uses a kthread, shut it down. */
 	IPMI_LOCK(sc);
Index: sys/dev/ipmi/ipmivars.h
===================================================================
--- sys/dev/ipmi/ipmivars.h
+++ sys/dev/ipmi/ipmivars.h
@@ -86,6 +86,13 @@
 	int	smbus_address;
 };
 
+/*
+ * More than enough for any request / reply when we're using the
+ * static buffer in restricted situtions. Request + reply lengths must
+ * be less than this.
+ */
+#define IPMI_STATIC_REQ_LEN	32
+
 struct ipmi_softc {
 	device_t		ipmi_dev;
 	union {
@@ -103,21 +110,28 @@
 	void			*ipmi_irq;
 	int			ipmi_detaching;
 	int			ipmi_opened;
+	uint8_t			ipmi_dev_support;	/* IPMI_ADS_* */
 	struct cdev		*ipmi_cdev;
 	TAILQ_HEAD(,ipmi_request) ipmi_pending_requests;
 	int			ipmi_driver_requests_polled;
+	eventhandler_tag	ipmi_power_cycle_tag;
 	eventhandler_tag	ipmi_watchdog_tag;
 	int			ipmi_watchdog_active;
 	struct intr_config_hook	ipmi_ich;
 	struct mtx		ipmi_requests_lock;
 	struct cv		ipmi_request_added;
 	struct proc		*ipmi_kthread;
+	union {
+		struct ipmi_request _req;
+		char buff[sizeof(ipmi_request) + IPMI_STATIC_REQ_LEN];
+	} _u;
 	driver_intr_t		*ipmi_intr;
 	int			(*ipmi_startup)(struct ipmi_softc *);
 	int			(*ipmi_enqueue_request)(struct ipmi_softc *, struct ipmi_request *);
 	int			(*ipmi_driver_request)(struct ipmi_softc *, struct ipmi_request *, int);
 };
 
+#define ipmi_static_req			_u.req
 #define	ipmi_ssif_smbus_address		_iface.ssif.smbus_address
 #define	ipmi_ssif_smbus			_iface.ssif.smbus
 
Index: sys/kern/kern_shutdown.c
===================================================================
--- sys/kern/kern_shutdown.c
+++ sys/kern/kern_shutdown.c
@@ -263,6 +263,8 @@
 		PROC_LOCK(initproc);
 		if (howto & RB_POWEROFF)
 			kern_psignal(initproc, SIGUSR2);
+		else if (howto & RB_POWERCYCLE)
+			kern_psignal(initproc, SIGUWINCH);
 		else if (howto & RB_HALT)
 			kern_psignal(initproc, SIGUSR1);
 		else
@@ -797,7 +799,7 @@
 poweroff_wait(void *junk, int howto)
 {
 
-	if (!(howto & RB_POWEROFF) || poweroff_delay <= 0)
+	if ((howto & (RB_POWEROFF | RB_POWERCYCLE)) == 0 || poweroff_delay <= 0)
 		return;
 	DELAY(poweroff_delay * 1000);
 }
Index: sys/sys/ipmi.h
===================================================================
--- sys/sys/ipmi.h
+++ sys/sys/ipmi.h
@@ -56,8 +56,25 @@
 #define IPMI_ASYNC_EVENT_RECV_TYPE      2
 #define IPMI_CMD_RECV_TYPE              3
 
+#define	IPMI_CHASIS_REQUEST		0x00
+# define IPMI_CHASIS_CONTROL		0x02
+#  define IPMI_CC_POWER_DOWN		0x0
+#  define IPMI_CC_POWER_UP		0x1
+#  define IPMI_CC_POWER_CYCLE		0x2
+#  define IPMI_CC_HARD_RESET		0x3
+#  define IPMI_CC_PULSE_DI		0x4
+#  define IPMI_CC_SOFT_OVERTEMP		0x5
+
 #define IPMI_APP_REQUEST		0x06
 #define IPMI_GET_DEVICE_ID		0x01
+# define IPMI_ADS_CHASSIS		0x80
+# define IPMI_ADS_BRIDGE		0x40
+# define IPMI_ADS_EVENT_GEN		0x20
+# define IPMI_ADS_EVENT_RCV		0x10
+# define IPMI_ADS_FRU_INV		0x08
+# define IPMI_ADS_SEL			0x04
+# define IPMI_ADS_SDR			0x02
+# define IPMI_ADS_SENSOR		0x01
 #define IPMI_CLEAR_FLAGS		0x30
 #define IPMI_GET_MSG_FLAGS		0x31
 # define IPMI_MSG_AVAILABLE		0x01
Index: sys/sys/reboot.h
===================================================================
--- sys/sys/reboot.h
+++ sys/sys/reboot.h
@@ -60,6 +60,7 @@
 #define	RB_RESERVED2	0x80000	/* reserved for internal use of boot blocks */
 #define	RB_PAUSE	0x100000 /* pause after each output line during probe */
 #define	RB_REROOT	0x200000 /* unmount the rootfs and mount it again */
+#define	RB_POWERCYCLE	0x400000 /* Power cycle if possible, otherwise POWEROFF */
 #define	RB_MULTIPLE	0x20000000	/* use multiple consoles */
 
 #define	RB_BOOTINFO	0x80000000	/* have `struct bootinfo *' arg */