evdev is the open source input driver for many input devices like keyboards, mice, joysticks and more.
You need USB support, if you have an USB input device. Also you need to activate the following kernel options:
Device Drivers ---> Input device support ---> <*> Event interface If a mouse is connected to a PS/2 port: [*] Mice ---> <*> PS/2 mouse If a keyboard is connected to a PS/2 port: -*- Keyboards ---> <*> AT keyboard If an input device is connected to an USB port: [*] HID Devices ---> -*- Generic HID support <*> USB Human Interface Device (full HID) support
Some USB mice (e.g. Logitech G5 and Razer Naga 2014) additionally need the following option:
Device Drivers ---> [*] USB support ---> [*] Improved Transaction Translator scheduling
After setting the INPUT_DEVICES variable remember to update the system using the following command so the changes take effect:
emerge --ask --changed-use --deep @world
To set the default layout copy the file 10-evdev.conf to /etc/X11/xorg.conf.d and edit the keyboard section, e.g. for a German layout:
cp /usr/share/X11/xorg.conf.d/10-evdev.conf /etc/X11/xorg.conf.d/
Section "InputClass" Identifier "evdev keyboard catchall" ... Driver "evdev" Option "xkb_layout" "de" EndSection
For more info please read the Configuring the keyboard.