diff -r 91c2ddbf51ba sys/dev/ata/ata.c
--- a/sys/dev/ata/ata.c	Thu Sep 24 15:54:22 2020 +0000
+++ b/sys/dev/ata/ata.c	Sat Oct 03 22:20:47 2020 +0000
@@ -298,7 +298,7 @@ atabusconfig(struct atabus_softc *atabus
 
 	ata_delref(chp);
 
-	config_pending_decr(atac->atac_dev);
+	config_pending_decr(atabus_sc->sc_dev);
 }
 
 /*
@@ -424,7 +424,7 @@ atabusconfig_thread(void *arg)
 
 	ata_delref(chp);
 
-	config_pending_decr(atac->atac_dev);
+	config_pending_decr(atabus_sc->sc_dev);
 	kthread_exit(0);
 }
 
diff -r 91c2ddbf51ba sys/kern/subr_autoconf.c
--- a/sys/kern/subr_autoconf.c	Thu Sep 24 15:54:22 2020 +0000
+++ b/sys/kern/subr_autoconf.c	Sat Oct 03 22:20:47 2020 +0000
@@ -224,7 +224,8 @@ static int alldevs_nread = 0;
 static int alldevs_nwrite = 0;
 static bool alldevs_garbage = false;
 
-static int config_pending;		/* semaphore for mountroot */
+static struct devicelist config_pending =
+    TAILQ_HEAD_INITIALIZER(config_pending);
 static kmutex_t config_misc_lock;
 static kcondvar_t config_misc_cv;
 
@@ -2095,9 +2096,12 @@ config_pending_incr(device_t dev)
 {
 
 	mutex_enter(&config_misc_lock);
-	config_pending++;
+	KASSERTMSG(dev->dv_pending < INT_MAX,
+	    "%s: excess config_pending_incr", device_xname(dev));
+	if (dev->dv_pending++ == 0)
+		TAILQ_INSERT_TAIL(&config_pending, dev, dv_pending_list);
 #ifdef DEBUG_AUTOCONF
-	printf("%s: %s %d\n", __func__, device_xname(dev), config_pending);
+	printf("%s: %s %d\n", __func__, device_xname(dev), dev->dv_pending);
 #endif
 	mutex_exit(&config_misc_lock);
 }
@@ -2106,13 +2110,15 @@ void
 config_pending_decr(device_t dev)
 {
 
-	KASSERT(0 < config_pending);
 	mutex_enter(&config_misc_lock);
-	config_pending--;
+	KASSERTMSG(dev->dv_pending > 0,
+	    "%s: excess config_pending_decr", device_xname(dev));
+	if (--dev->dv_pending == 0)
+		TAILQ_REMOVE(&config_pending, dev, dv_pending_list);
 #ifdef DEBUG_AUTOCONF
-	printf("%s: %s %d\n", __func__, device_xname(dev), config_pending);
+	printf("%s: %s %d\n", __func__, device_xname(dev), dev->dv_pending);
 #endif
-	if (config_pending == 0)
+	if (TAILQ_EMPTY(&config_pending))
 		cv_broadcast(&config_misc_cv);
 	mutex_exit(&config_misc_lock);
 }
@@ -2165,8 +2171,12 @@ config_finalize(void)
 	 * them to finish any deferred autoconfiguration.
 	 */
 	mutex_enter(&config_misc_lock);
-	while (config_pending != 0)
+	while (!TAILQ_EMPTY(&config_pending)) {
+		device_t dev;
+		TAILQ_FOREACH(dev, &config_pending, dv_pending_list)
+			aprint_debug_dev(dev, "holding up boot\n");
 		cv_wait(&config_misc_cv, &config_misc_lock);
+	}
 	mutex_exit(&config_misc_lock);
 
 	KERNEL_LOCK(1, NULL);
diff -r 91c2ddbf51ba sys/sys/device.h
--- a/sys/sys/device.h	Thu Sep 24 15:54:22 2020 +0000
+++ b/sys/sys/device.h	Sat Oct 03 22:20:47 2020 +0000
@@ -165,6 +165,9 @@ struct device {
 	int		*dv_locators;	/* our actual locators (optional) */
 	prop_dictionary_t dv_properties;/* properties dictionary */
 
+	int		dv_pending;	/* config_pending count */
+	TAILQ_ENTRY(device) dv_pending_list;
+
 	size_t		dv_activity_count;
 	void		(**dv_activity_handlers)(device_t, devactive_t);