Index: sys/kern/vfs_mountroot.c
===================================================================
--- sys/kern/vfs_mountroot.c	(revision 274644)
+++ sys/kern/vfs_mountroot.c	(working copy)
@@ -479,28 +479,36 @@
 	printf("  .               Yield 1 second (for background tasks)\n");
 	printf("  <empty line>    Abort manual input\n");
 
-	do {
+	if (kern_getenv("debug.rootfs_mount_fail_dontask") != NULL) {
+		printf("\ndebug.rootfs_mount_fail_dontask found - panic / reboot in 3 seconds\n");
+		DELAY(3000000);
 		error = EINVAL;
-		printf("\nmountroot> ");
-		cngets(name, sizeof(name), GETS_ECHO);
-		if (name[0] == '\0')
-			break;
-		if (name[0] == '?' && name[1] == '\0') {
-			printf("\nList of GEOM managed disk devices:\n  ");
-			g_dev_print();
-			continue;
-		}
-		if (name[0] == '.' && name[1] == '\0') {
-			pause("rmask", hz);
-			continue;
-		}
-		mnt = name;
-		error = parse_mount(&mnt);
-		if (error == -1)
-			printf("Invalid file system specification.\n");
-	} while (error != 0);
+		return (error);
+	}
+	else {
+		do {
+			error = EINVAL;
+			printf("\nmountroot> ");
+			cngets(name, sizeof(name), GETS_ECHO);
+			if (name[0] == '\0')
+				break;
+			if (name[0] == '?' && name[1] == '\0') {
+				printf("\nList of GEOM managed disk devices:\n  ");
+				g_dev_print();
+				continue;
+			}
+			if (name[0] == '.' && name[1] == '\0') {
+				pause("rmask", hz);
+				continue;
+			}
+			mnt = name;
+			error = parse_mount(&mnt);
+			if (error == -1)
+				printf("Invalid file system specification.\n");
+		} while (error != 0);
 
-	return (error);
+		return (error);
+	}
 }
 
 static int