There's a possibility to run into IA32 EFI but that's rather
uninteresting hardware (ancient Xeon servers and <s>outdated</s>
early Intel Mac laptops).  Just drop it on the floor.

As x86_64 UEFI support would result in "2D hybrid(r)(tm)" image
which boots with all combinations of BIOS/UEFI by CD|DVD/Flash
(or at least should boot), some downgrace seems due: use/efi will
turn use/isohybrid on non-x86_64 -- which will require further
tweaks on PPC/ARM some day.