> As UEFI needs a FAT partition /boot/efi/efi, > can I create it from my previous /boot partition?
I haven't tried it yet - my /boot and /boot/efi are still two seperate partitions on my sys - but in theory it should work just fine with only a UEFI partition as the UEFI bootloader just loads the grub2 loader (I don't know what it's called, sorry. but I mean the grubx64.efi file) and then grub2 loads the rest. grub2 does not care where the stuff is, it just needs to know where to find the files (and maybe load some extra modules if you keep your files on a rare filesystem, raid, lvm, etc...).
