diff --git a/sys/conf/options b/sys/conf/options
index 2c0a183594f..9e244762ac3 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -904,3 +904,8 @@ RACCT		opt_global.h
 
 # Resource Limits
 RCTL		opt_global.h
+
+# Random number generator(s)
+YARROW_RNG	opt_random.h
+FORTUNA_RNG	opt_random.h
+RANDOM_DEBUG	opt_random.h
diff --git a/sys/dev/random/random_adaptors.c b/sys/dev/random/random_adaptors.c
index 3d582146226..8cbebbce4c8 100644
--- a/sys/dev/random/random_adaptors.c
+++ b/sys/dev/random/random_adaptors.c
@@ -227,3 +227,17 @@ SYSINIT(random_adaptors, SI_SUB_DRIVERS, SI_ORDER_FIRST, random_adaptors_init,
     NULL);
 SYSUNINIT(random_adaptors, SI_SUB_DRIVERS, SI_ORDER_FIRST,
     random_adaptors_deinit, NULL);
+
+static void
+random_adaptors_reseed(void *unused)
+{
+
+	(void)unused;
+	if (random_adaptor != NULL) {
+		(*random_adaptor->reseed)();
+		random_adaptor->seeded = 1;
+	}
+	arc4rand(NULL, 0, 1);
+}
+SYSINIT(random_reseed, SI_SUB_INTRINSIC_POST, SI_ORDER_SECOND,
+    random_adaptors_reseed, NULL);
diff --git a/sys/dev/random/randomdev_soft.c b/sys/dev/random/randomdev_soft.c
index 352d0ae789e..9c3aa5366c6 100644
--- a/sys/dev/random/randomdev_soft.c
+++ b/sys/dev/random/randomdev_soft.c
@@ -26,11 +26,16 @@
  *
  */
 
+#include "opt_random.h"
+
 #if !defined(YARROW_RNG) && !defined(FORTUNA_RNG)
 #define YARROW_RNG
 #elif defined(YARROW_RNG) && defined(FORTUNA_RNG)
 #error "Must define either YARROW_RNG or FORTUNA_RNG"
 #endif
+#if defined(FORTUNA_RNG)
+#error "Fortuna is not yet implemented"
+#endif
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
diff --git a/sys/dev/random/yarrow.c b/sys/dev/random/yarrow.c
index 6d2ea3b48fd..1cfa37372ed 100644
--- a/sys/dev/random/yarrow.c
+++ b/sys/dev/random/yarrow.c
@@ -28,6 +28,8 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include "opt_random.h"
+
 #include <sys/param.h>
 #include <sys/kernel.h>
 #include <sys/lock.h>
@@ -398,5 +400,17 @@ generator_gate(void)
 void
 random_yarrow_reseed(void)
 {
+#ifdef RANDOM_DEBUG
+	int i;
+
+	printf("%s(): fast:", __func__);
+	for (i = RANDOM_START; i < ENTROPYSOURCE; ++i)
+		printf(" %d", random_state.pool[FAST].source[i].bits);
+	printf("\n");
+	printf("%s(): slow:", __func__);
+	for (i = RANDOM_START; i < ENTROPYSOURCE; ++i)
+		printf(" %d", random_state.pool[SLOW].source[i].bits);
+	printf("\n");
+#endif
 	reseed(SLOW);
 }
diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c
index b3b1852cada..5c4c3297f14 100644
--- a/sys/kern/subr_bus.c
+++ b/sys/kern/subr_bus.c
@@ -28,6 +28,7 @@
 __FBSDID("$FreeBSD$");
 
 #include "opt_bus.h"
+#include "opt_random.h"
 
 #include <sys/param.h>
 #include <sys/conf.h>
@@ -44,6 +45,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/condvar.h>
 #include <sys/queue.h>
 #include <machine/bus.h>
+#include <sys/random.h>
 #include <sys/rman.h>
 #include <sys/selinfo.h>
 #include <sys/signalvar.h>
@@ -55,6 +57,7 @@ __FBSDID("$FreeBSD$");
 
 #include <net/vnet.h>
 
+#include <machine/cpu.h>
 #include <machine/stdarg.h>
 
 #include <vm/uma.h>
@@ -2766,6 +2769,7 @@ device_probe_and_attach(device_t dev)
 int
 device_attach(device_t dev)
 {
+	uint64_t attachtime;
 	int error;
 
 	if (resource_disabled(dev->driver->name, dev->unit)) {
@@ -2778,6 +2782,7 @@ device_attach(device_t dev)
 	device_sysctl_init(dev);
 	if (!device_is_quiet(dev))
 		device_print_child(dev->parent, dev);
+	attachtime = get_cyclecount();
 	dev->state = DS_ATTACHING;
 	if ((error = DEVICE_ATTACH(dev)) != 0) {
 		printf("device_attach: %s%d attach returned %d\n",
@@ -2790,6 +2795,17 @@ device_attach(device_t dev)
 		dev->state = DS_NOTPRESENT;
 		return (error);
 	}
+	attachtime = get_cyclecount() - attachtime;
+	/*
+	 * 4 bits per device is a reasonable value for desktop and server
+	 * hardware with good get_cyclecount() implementations, but may
+	 * need to be adjusted on other platforms.
+	 */
+#ifdef RANDOM_DEBUG
+	printf("%s(): feeding %d bit(s) of entropy from %s%d\n",
+	    __func__, 4, dev->driver->name, dev->unit);
+#endif
+	random_harvest(&attachtime, sizeof(attachtime), 4, RANDOM_ATTACH);
 	device_sysctl_update(dev);
 	if (dev->busy)
 		dev->state = DS_BUSY;
diff --git a/sys/modules/random/Makefile b/sys/modules/random/Makefile
index 60b62afde1d..a0c6077de88 100644
--- a/sys/modules/random/Makefile
+++ b/sys/modules/random/Makefile
@@ -12,7 +12,7 @@ SRCS+=	ivy.c
 .endif
 SRCS+=	randomdev_soft.c yarrow.c hash.c
 SRCS+=	rijndael-alg-fst.c rijndael-api-fst.c sha2.c
-SRCS+=	bus_if.h device_if.h vnode_if.h opt_cpu.h
+SRCS+=	bus_if.h device_if.h vnode_if.h opt_cpu.h opt_random.h
 
 CFLAGS+= -I${.CURDIR}/../..
 
diff --git a/sys/sys/random.h b/sys/sys/random.h
index 1ccad3af239..68bb2627373 100644
--- a/sys/sys/random.h
+++ b/sys/sys/random.h
@@ -46,6 +46,7 @@ enum esource {
 	RANDOM_NET_ETHER,
 	RANDOM_NET_NG,
 	RANDOM_INTERRUPT,
+	RANDOM_ATTACH,
 	RANDOM_SWI,
 	RANDOM_PURE_OCTEON,
 	RANDOM_PURE_SAFE,