I meet the problem that virtual media couldn't support in BIOS or UEFI.  

When I use HP EliteDesk 800 G6 Desktop Mini PC and try to mount the drive in BIOS and install the OS, I couldn't mount it successfully. 

But if I mount it in Windows OS, it works fine.  

I see the description "Supports providing a command to solve that virtual media mount under BIOS mode may cause keyboard and mouse movement not working" in firmware release note of v2.8.277 firmware version.

How to use the command to solve the problem?

The command is setmountmode [port number] [mode]

For example:

It means you enable the function on port 9. Change 1 to 0 means disable the function.

If the command couldn't solve the problem, please update the BIOS or UEFI version to the latest one to improve the compatibility.

Also, if you try to mount an USB drive, please don't connect other USB devices on your PC or laptop.  Some PC/laptop only support 1 or 2 USB devices to connect when it's in BIOS or UEFI.