Comment # 15 on bug 1205261 from Felix Miata

arvidjaar in forums[1] told someone (without any real detail) he needs to
bind-mount /sys/firmware/efi/efivars to be able to chroot successfully for the
purpose of initrd regeneration. I've never seen that direction before. Coming
from him, I have to think it to be true. Could it explain why chroot-built
initrds haven't worked for me?

[1]
<https://forums.opensuse.org/t/reinstalling-grub-after-losing-dual-boot/165169/6>