Check the install instructions page as well:
https://libreboot.org/docs/install/
"Available modes: vesafb or txtmode. The vesafb ROM images are recommended,
in most cases; txtmode ROM images come with MemTest86+, which requires
text-mode instead of the usual framebuffer used by coreboot native graphics
initialization."
I used vesafb like recommended.
Remember, you have to go through the whole process of disassembling only
once. Updates can then be flashed via terminal.
@stas
Sorry,my Russian is pretty bad so I answer in English. I can't think of a
reason why one shouldn't be allowed to use the Russian alphabet for the
username. Worked for me ;-)