Stefan Fiedler:

package/base/rockinitrd/initrd_base.txt

@@ -15,6 +15,7 @@
 /sbin/udevtrigger	/sbin/udevtrigger
 /sbin/udevsettle	/sbin/udevsettle
 /sbin/udevd	/sbin/udevd
+/sbin/modprobe	/sbin/modprobe
 /etc/udev	/etc/udev
 /lib/udev	/lib/udev
 /etc/hotplug.d /etc/hotplug.d