Translations:EFI stub/20/en
From Gentoo Wiki
Tip
Some rare (U)EFI implementations do not accept individual EFI entries. In this case it often works to use the removable media boot path, see Efibootmgr #removable media for details. E.g. this command will copy the kernel for a 64 bit UEFI: Be advised that this is against the (U)EFI specification, as it will circumvent the (U)EFI boot selection on internal drives (which are configured using EFI boot entries).
Some rare (U)EFI implementations do not accept individual EFI entries. In this case it often works to use the removable media boot path, see Efibootmgr #removable media for details. E.g. this command will copy the kernel for a 64 bit UEFI:
root #cp /usr/src/linux/arch/x86/boot/bzImage /efi/EFI/boot/bootx64.efi