Garbled text halfway through bootup
 

I just installed Gentoo on a Hyper-V instance. Halfway through the boot process (I think when the graphical part of the boot starts), the text gets displayed as garbage (like in a symbol font or something). At this point I login and run locale-gen and the font gets fixed.

I am using systemd and I have set the locale with localectl. I have been trying to setup the GFXMODE parameters in /etc/default/grub, but I am not sure if I need to do a new grub2-mkconfig -io /boot/grub/grub.cfg to "deploy" my changes.

Yes you do.
Is that a typo on the mkconfig - what is -i ?.