arch Linux boots into grub command line

I found a case when I tried to use gummiboot instead of grub. Gummiboot reported an error: that it can't find kernel images. It looks like I mounted /boot and configured fstab after I installed the base system with pacstrap -i. So kernel images that were placed in a /boot directory were lost after mounting, and thus the system could not boot. I wonder what happened with them? Are they were still on hard drive, but were just shadowed with mounted partition?

Anyway, I just reinstalled everything again with carefully following instructions on the Arch wiki and it works now.