I have no option for a UEFI shell on my Lenovo U400. I'm triple booting Windows 10, Debian Sid, and FreeBSD 13.0-CURRENT (soon to add macOS Mojave to that) with rEFInd. I want an option for the EFI shell, but my EFI interface (Lenovo 57CN30WW) doesn't have a built-in shell, nor does my EFI partition have a shellx64.efi binary. I heard about the EDK II, but I have no idea how to build it on a Linux system, or a Windows system for that matter. I don't know how to use it exactly either. How would I get an EFI shell up and running on my system, preferably from Debian?