Sorry for not being specific enough. when I sad "a bit small" I was talking about the part of the screen used by the console -- alredy from booting. That is getty is not responsible, but I now recalls, that the problem also exits when Windows fails to boot. I'll just take a look at the settings in the BIOS.
I am not sure I understood you correctly, but maybe you want to read "svga.txt" in kernel documentation. If this is what you are looking for, please also read the docs in "fb", especially "fb/fbcon.txt" and "fb/vesafb.txt".
You might need to install a kernel-doc package to find these files. They will be in either "linux-doc" or "kernel-doc" at "/usr/share/doc".