Ubuntu is really stupid about EFI. The installer sucks horribly. UEFI can absolutely do what you want. The best way to set up an external OS on a USB is, ideally, to disconnect every other drive ...

UEFI Boot (Secure Boot Disabled): Every system I have used which has UEFI firmware has had the possibility to disable Secure Boot, but still use EFI boot.

In other terms, EFI is a storage partition that goes with UEFI or Unified Extensible Firmware Interface. That being said, if you want to UEFI, you have to use the EFI as well.

Exploiting a known UEFI firmware vulnerability (e.g., CVE-2014-2961, CVE-2014-8274, or CVE-2015-0949) in the case of an outdated firmware version or a no-longer-supported product.

If you use a UEFI system instead of BIOS, you can find an additional particular called EFI System Partition. It stores the data of the EFI bootloader, which is mainly some .efi files.

I apologize if I should have put this in the Mac section, but it isn't really a Mac inquiry. We just removed the last of our 2010 and 2012 Mac Pro towers from production about a month ago, most of ...