спасибо, наконец то удалось найти более менее приличное описание

https://www.happyassassin.net/2014/01/25/uefi-boot-how-doe...

Хотя там требуют GPT formatted disk.

Enabling UEFI native boot

To be bootable in UEFI native mode, your OS installation medium must obviously actually comply with all this stuff we’ve just described: it’s got to have a GPT partition table, and an EFI system partition with a bootloader in the correct ‘fallback’ path – \EFI\BOOT\BOOTx64.EFI (or the other names for the other platforms). If you’re having trouble doing a UEFI native boot of your installation medium and can’t figure out why, check that this is actually the case. Notably, when using the livecd-iso-to-disk tool to write a Fedora image to a USB stick, you must pass the --efi parameter to configure the stick to be UEFI bootable.

...

Of course, to make life complicated, many firmwares can boot BIOS-style from a GPT formatted disk. UEFI firmwares are in fact technically required to be able to boot UEFI-style from an MBR formatted disk (though we are not particularly confident that they all really can). But you really should avoid this if at all possible.

А что будет если на флэшке/исо нет папки EFI?