- this optional extension adds an initramfs script that:
- enumerates and filters all block devices
- exposes each device as an UMS (USB Mass Storage) in an USB Gadget
- loops forever with info (board never boots)
- the idea here is to compensate for UEFI's lack of "ums" or "rockusb" mode that's present in u-boot
- it also allows to expose USB/NVMe devices that might or not be detected by bootloader, if the kernel works
