diff --git a/sys/arm/ti/am335x/am335x_pmic.c b/sys/arm/ti/am335x/am335x_pmic.c
--- a/sys/arm/ti/am335x/am335x_pmic.c
+++ b/sys/arm/ti/am335x/am335x_pmic.c
@@ -90,7 +90,6 @@
 	struct tps65217_status_reg status_reg;
 	struct tps65217_int_reg int_reg;
 	int rv;
-	char notify_buf[16];
 
 	THREAD_SLEEPING_OK();
 	rv = am335x_pmic_read(sc->sc_dev, TPS65217_INT_REG, (uint8_t *)&int_reg, 1);
@@ -110,9 +109,8 @@
 	if (int_reg.pbi && status_reg.pb)
 		shutdown_nice(RB_POWEROFF);
 	if (int_reg.aci) {
-		snprintf(notify_buf, sizeof(notify_buf), "notify=0x%02x",
+		devctl_notifyf("ACPI", "ACAD", "power", "notify=0x%02x",
 		    status_reg.acpwr);
-		devctl_notify("ACPI", "ACAD", "power", notify_buf);
 	}
 }
 
diff --git a/sys/dev/acpica/acpi.c b/sys/dev/acpica/acpi.c
--- a/sys/dev/acpica/acpi.c
+++ b/sys/dev/acpica/acpi.c
@@ -4278,7 +4278,6 @@
 void
 acpi_UserNotify(const char *subsystem, ACPI_HANDLE h, uint8_t notify)
 {
-    char		notify_buf[16];
     ACPI_BUFFER		handle_buf;
     ACPI_STATUS		status;
 
@@ -4290,8 +4289,8 @@
     status = AcpiNsHandleToPathname(h, &handle_buf, FALSE);
     if (ACPI_FAILURE(status))
 	return;
-    snprintf(notify_buf, sizeof(notify_buf), "notify=0x%02x", notify);
-    devctl_notify("ACPI", subsystem, handle_buf.Pointer, notify_buf);
+    devctl_notifyf("ACPI", subsystem, handle_buf.Pointer, "notify=0x%02x",
+        notify);
     AcpiOsFree(handle_buf.Pointer);
 }
 
diff --git a/sys/dev/asmc/asmc.c b/sys/dev/asmc/asmc.c
--- a/sys/dev/asmc/asmc.c
+++ b/sys/dev/asmc/asmc.c
@@ -1458,7 +1458,6 @@
 asmc_sms_task(void *arg, int pending)
 {
 	struct asmc_softc *sc = (struct asmc_softc *)arg;
-	char notify[16];
 	int type;
 
 	switch (sc->sc_sms_intrtype) {
@@ -1475,8 +1474,7 @@
 		type = 255;
 	}
 
-	snprintf(notify, sizeof(notify), " notify=0x%x", type);
-	devctl_notify("ACPI", "asmc", "SMS", notify);
+	devctl_notifyf("ACPI", "asmc", "SMS", "notify=0x%x", type);
 }
 
 static int
diff --git a/sys/dev/usb/usb_device.c b/sys/dev/usb/usb_device.c
--- a/sys/dev/usb/usb_device.c
+++ b/sys/dev/usb/usb_device.c
@@ -2698,12 +2698,10 @@
 usb_notify_addq(const char *type, struct usb_device *udev)
 {
 	struct usb_interface *iface;
-	struct sbuf *sb;
 	int i;
 
 	/* announce the device */
-	sb = sbuf_new_auto();
-	sbuf_printf(sb,
+	devctl_notifyf("USB", "DEVICE", type,
 #if USB_HAVE_UGEN
 	    "ugen=%s "
 	    "cdev=%s "
@@ -2738,9 +2736,6 @@
 		device_get_nameunit(device_get_parent(udev->bus->bdev))
 #endif
 	    );
-	sbuf_finish(sb);
-	devctl_notify("USB", "DEVICE", type, sbuf_data(sb));
-	sbuf_delete(sb);
 
 	/* announce each interface */
 	for (i = 0; i < USB_IFACE_MAX; i++) {
@@ -2750,8 +2745,7 @@
 		if (iface->idesc == NULL)
 			continue;	/* no interface descriptor */
 
-		sb = sbuf_new_auto();
-		sbuf_printf(sb,
+		devctl_notifyf("USB", "INTERFACE", type,
 #if USB_HAVE_UGEN
 		    "ugen=%s "
 		    "cdev=%s "
@@ -2784,9 +2778,6 @@
 		    iface->idesc->bInterfaceClass,
 		    iface->idesc->bInterfaceSubClass,
 		    iface->idesc->bInterfaceProtocol);
-		sbuf_finish(sb);
-		devctl_notify("USB", "INTERFACE", type, sbuf_data(sb));
-		sbuf_delete(sb);
 	}
 }
 #endif
diff --git a/sys/dev/vt/vt_core.c b/sys/dev/vt/vt_core.c
--- a/sys/dev/vt/vt_core.c
+++ b/sys/dev/vt/vt_core.c
@@ -1095,25 +1095,14 @@
 	return (idx0);
 }
 
-#define DEVCTL_LEN 64
 static void
 vtterm_devctl(bool enabled, bool hushed, int hz, sbintime_t duration)
 {
-	struct sbuf sb;
-	char *buf;
 
-	buf = malloc(DEVCTL_LEN, M_VT, M_NOWAIT);
-	if (buf == NULL)
-		return;
-	sbuf_new(&sb, buf, DEVCTL_LEN, SBUF_FIXEDLEN);
-	sbuf_printf(&sb, "enabled=%s hushed=%s hz=%d duration_ms=%d",
+	devctl_notifyf("VT", "BELL", "RING",
+	     "enabled=%s hushed=%s hz=%d duration_ms=%d",
 	    enabled ? "true" : "false", hushed ? "true" : "false",
 	    hz, (int)(duration / SBT_1MS));
-	sbuf_finish(&sb);
-	if (sbuf_error(&sb) == 0)
-		devctl_notify("VT", "BELL", "RING", sbuf_data(&sb));
-	sbuf_delete(&sb);
-	free(buf, M_VT);
 }
 
 static void
diff --git a/sys/geom/geom_dev.c b/sys/geom/geom_dev.c
--- a/sys/geom/geom_dev.c
+++ b/sys/geom/geom_dev.c
@@ -215,15 +215,13 @@
 	struct g_consumer *cp;
 	struct g_geom *gp;
 	struct g_dev_softc *sc;
-	char buf[SPECNAMELEN + 6];
 
 	g_topology_assert();
 	cp = arg;
 	gp = cp->geom;
 	sc = cp->private;
 	g_trace(G_T_TOPOLOGY, "g_dev_destroy(%p(%s))", cp, gp->name);
-	snprintf(buf, sizeof(buf), "cdev=%s", gp->name);
-	devctl_notify("GEOM", "DEV", "DESTROY", buf);
+	devctl_notifyf("GEOM", "DEV", "DESTROY", "cdev=%s", gp->name);
 	knlist_clear(&sc->sc_selinfo.si_note, 0);
 	knlist_destroy(&sc->sc_selinfo.si_note);
 	if (cp->acr > 0 || cp->acw > 0 || cp->ace > 0)
@@ -284,18 +282,17 @@
 {
 	struct g_dev_softc *sc;
 	struct cdev *dev;
-	char buf[SPECNAMELEN + 6];
 
 	sc = cp->private;
 	dev = sc->sc_dev;
-	snprintf(buf, sizeof(buf), "cdev=%s", dev->si_name);
-	devctl_notify("DEVFS", "CDEV", "MEDIACHANGE", buf);
-	devctl_notify("GEOM", "DEV", "MEDIACHANGE", buf);
+	devctl_notifyf("DEVFS", "CDEV", "MEDIACHANGE", "cdev=%s", dev->si_name);
+	devctl_notifyf("GEOM", "DEV", "MEDIACHANGE", "cdev=%s", dev->si_name);
 	dev = sc->sc_alias;
 	if (dev != NULL) {
-		snprintf(buf, sizeof(buf), "cdev=%s", dev->si_name);
-		devctl_notify("DEVFS", "CDEV", "MEDIACHANGE", buf);
-		devctl_notify("GEOM", "DEV", "MEDIACHANGE", buf);
+		devctl_notifyf("DEVFS", "CDEV", "MEDIACHANGE", "cdev=%s",
+		    dev->si_name);
+		devctl_notifyf("GEOM", "DEV", "MEDIACHANGE", "cdev=%s",
+		    dev->si_name);
 	}
 }
 
@@ -318,13 +315,12 @@
 g_dev_resize(struct g_consumer *cp)
 {
 	struct g_dev_softc *sc;
-	char buf[SPECNAMELEN + 6];
 
 	sc = cp->private;
 	KNOTE_UNLOCKED(&sc->sc_selinfo.si_note, NOTE_ATTRIB);
 
-	snprintf(buf, sizeof(buf), "cdev=%s", cp->provider->name);
-	devctl_notify("GEOM", "DEV", "SIZECHANGE", buf);
+	devctl_notifyf("GEOM", "DEV", "SIZECHANGE", "cdev=%s",
+	    cp->provider->name);
 }
 
 struct g_provider *
@@ -350,7 +346,6 @@
 	struct g_dev_softc *sc;
 	int error;
 	struct cdev *dev, *adev;
-	char buf[SPECNAMELEN + 6];
 	struct make_dev_args args;
 
 	g_trace(G_T_TOPOLOGY, "dev_taste(%s,%s)", mp->name, pp->name);
@@ -401,8 +396,7 @@
 		    __func__, gp->name, error);
 
 	g_dev_attrchanged(cp, "GEOM::physpath");
-	snprintf(buf, sizeof(buf), "cdev=%s", gp->name);
-	devctl_notify("GEOM", "DEV", "CREATE", buf);
+	devctl_notifyf("GEOM", "DEV", "CREATE", "cdev=%s", gp->name);
 	/*
 	 * Now add all the aliases for this drive
 	 */
@@ -414,8 +408,7 @@
 			    __func__, gap->ga_alias, error);
 			continue;
 		}
-		snprintf(buf, sizeof(buf), "cdev=%s", gap->ga_alias);
-		devctl_notify("GEOM", "DEV", "CREATE", buf);
+		devctl_notifyf("GEOM", "DEV", "CREATE", "cdev=%s", gap->ga_alias);
 	}
 
 	return (gp);
diff --git a/sys/geom/geom_disk.c b/sys/geom/geom_disk.c
--- a/sys/geom/geom_disk.c
+++ b/sys/geom/geom_disk.c
@@ -1001,15 +1001,13 @@
 {
 	struct g_geom *gp = dp->d_geom;
 	struct g_provider *pp;
-	char devnamebuf[128];
 
 	if (gp == NULL)
 		return;
 	LIST_FOREACH(pp, &gp->provider, provider)
 		(void)g_attr_changed(pp, attr, flag);
-	snprintf(devnamebuf, sizeof(devnamebuf), "devname=%s%d", dp->d_name,
+	devctl_notifyf("GEOM", "disk", attr, "devname=%s%d", dp->d_name,
 	    dp->d_unit);
-	devctl_notify("GEOM", "disk", attr, devnamebuf);
 }
 
 void
diff --git a/sys/kern/kern_conf.c b/sys/kern/kern_conf.c
--- a/sys/kern/kern_conf.c
+++ b/sys/kern/kern_conf.c
@@ -529,21 +529,10 @@
 static void
 notify(struct cdev *dev, const char *ev, int flags)
 {
-	static const char prefix[] = "cdev=";
-	char *data;
-	int namelen, mflags;
 
 	if (cold)
 		return;
-	mflags = (flags & MAKEDEV_NOWAIT) ? M_NOWAIT : M_WAITOK;
-	namelen = strlen(dev->si_name);
-	data = malloc(namelen + sizeof(prefix), M_TEMP, mflags);
-	if (data == NULL)
-		return;
-	memcpy(data, prefix, sizeof(prefix) - 1);
-	memcpy(data + sizeof(prefix) - 1, dev->si_name, namelen + 1);
-	devctl_notify("DEVFS", "CDEV", ev, data);
-	free(data, M_TEMP);
+	devctl_notifyf("DEVFS", "CDEV", ev, "cdev=%s", dev->si_name);
 }
 
 static void
diff --git a/sys/net/if.c b/sys/net/if.c
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -3128,7 +3128,6 @@
 	struct sockaddr_dl *sdl;
 	size_t namelen, onamelen;
 	char old_name[IFNAMSIZ];
-	char strbuf[IFNAMSIZ + 8];
 
 	if (new_name[0] == '\0')
 		return (EINVAL);
@@ -3177,8 +3176,7 @@
 
 	ifp->if_flags &= ~IFF_RENAMING;
 
-	snprintf(strbuf, sizeof(strbuf), "name=%s", new_name);
-	devctl_notify("IFNET", old_name, "RENAME", strbuf);
+	devctl_notifyf("IFNET", old_name, "RENAME", "name=%s", new_name);
 
 	return (0);
 }
diff --git a/sys/net/route.c b/sys/net/route.c
--- a/sys/net/route.c
+++ b/sys/net/route.c
@@ -624,23 +624,21 @@
 #ifdef INET
 	if (sa->sa_family == AF_INET) {
 		char addrstr[INET_ADDRSTRLEN];
-		char strbuf[INET_ADDRSTRLEN + 12];
 
 		inet_ntoa_r(((struct sockaddr_in *)sa)->sin_addr, addrstr);
-		snprintf(strbuf, sizeof(strbuf), "address=%s", addrstr);
-		devctl_notify("IFNET", ifp->if_xname,
-		    (cmd == RTM_ADD) ? "ADDR_ADD" : "ADDR_DEL", strbuf);
+		devctl_notifyf("IFNET", ifp->if_xname,
+		    (cmd == RTM_ADD) ? "ADDR_ADD" : "ADDR_DEL",
+		    "address=%s", addrstr);
 	}
 #endif
 #ifdef INET6
 	if (sa->sa_family == AF_INET6) {
 		char addrstr[INET6_ADDRSTRLEN];
-		char strbuf[INET6_ADDRSTRLEN + 12];
 
 		ip6_sprintf(addrstr, IFA_IN6(ifa));
-		snprintf(strbuf, sizeof(strbuf), "address=%s", addrstr);
-		devctl_notify("IFNET", ifp->if_xname,
-		    (cmd == RTM_ADD) ? "ADDR_ADD" : "ADDR_DEL", strbuf);
+		devctl_notifyf("IFNET", ifp->if_xname,
+		    (cmd == RTM_ADD) ? "ADDR_ADD" : "ADDR_DEL",
+		    "address=%s", addrstr);
 	}
 #endif
 
diff --git a/sys/powerpc/powermac/pmu.c b/sys/powerpc/powermac/pmu.c
--- a/sys/powerpc/powermac/pmu.c
+++ b/sys/powerpc/powermac/pmu.c
@@ -949,16 +949,14 @@
 static void
 pmu_battery_notify(struct pmu_battstate *batt, struct pmu_battstate *old)
 {
-	char notify_buf[16];
 	int new_acline, old_acline;
 
 	new_acline = (batt->state & PMU_PWR_AC_PRESENT) ? 1 : 0;
 	old_acline = (old->state & PMU_PWR_AC_PRESENT) ? 1 : 0;
 
 	if (new_acline != old_acline) {
-		snprintf(notify_buf, sizeof(notify_buf),
-		    "notify=0x%02x", new_acline);
-		devctl_notify("PMU", "POWER", "ACLINE", notify_buf);
+		devctl_notifyf("PMU", "POWER", "ACLINE", "notify=0x%02x",
+		    new_acline);
 	}
 }