Refer to b/65606804, we found that in the factory shim frecon can't detect new input device when switch_root() is called to move rootfs from initramfs to another one. 

The impact is that all default keyboard of detachable projects which leverage design of hammer would not work correctly in the menu of factory shim. On the other hand, for tablet project if users plug USB keyboard after booting to menu of factory shim then this keyboard would not work too (it can work if plug USB keyboard before booting).