It has been requested that we make support for the i8042 keyboard and mouse controller modular. Some people get weird error messages because they don't have one and the manual probing slows down their boot. Tom took care of this on the kernel side (thank you) and the result finally landed in 3.13.
In order to get keyboard input during early init, if you don't have it already, add the keyboard hook to the HOOKS= line in /etc/mkinitcpio.conf and run mkinitcpio -P. It has been in the default configuration for some time.
WARNING: There's a downside to all this: On some motherboards (mostly ancient ones, but also a few new ones), the i8042 controller cannot be automatically detected. It's rare, but some people will surely be without keyboard. You can detect this situation in advance:
$ dmesg -t | grep '^i8042'
i8042: PNP: No PS/2 controller found. Probing ports directly.
If you have a PS/2 port and get this message, add atkbd to the MODULES= line in mkinitcpio.conf and run mkinitcpio -P. If you just noticed that you are without keyboard after rebooting, fear not! Simply add
earlymodules=atkbd modules-load=atkbd
to your kernel command line in your bootloader.
I will move Linux 3.13 to [core] a few hours from now, to give everyone a chance to read this before upgrading. I apologize for any inconvenience this transition may cause.