Windows 8 may disable keyboard on boot (Fast Boot feature)?

There is quite interesting post on systemd list:

This is part of work I’m doing to let us run reasonably with “Windows 8
Fast Boot” features turned on, which aim at making normal boots not
initialize the keyboard, or indeed the entire USB stack (unless it’s
used in a already-defined boot option) thus saving several seconds during
boot up. Obviously that means not getting keyboard input from the firmware,
bootloaders, and so forth, which means we need alternate ways to select
those types of options.
This may explain some weird effects that were recently brought up here.

Anyone knows about this “feature” and can provide some pointers to it?

There is already a thread about this:

Thank you!