How to solve grub2 installation problem?

Question

linux

I'm trying to install grub2 on /dev/sdb3.

(chroot) desktop / # mount /dev/sdb3 /boot
(chroot) desktop / # grub2-install --target=x86_64-efi --efi-directory=/boot
Installing for x86_64-efi platform.
efibootmgr: EFI variables are not supported on this system.
efibootmgr: EFI variables are not supported on this system.
Установка завершена. Ошибок нет.

gentoo distribution. The flash drive is formatted in fat32. nano /etc/portage/make.conf has GRUB_PLATFORMS="efi-64".

Answer 1

CONFIG_EFI_VARS=yenabled in the kernel ?
Is the system booted via efi?