evdev

evdev is

The open source input driver (x11-drivers/xf86-input-evdev) for many input devices like keyboards, mice, joysticks and more.
The short name of the Linux kernel's event interface (CONFIG_INPUT_EVDEV), needed for libinput.
The input_devices_evdev USE flag.

Installation

Kernel

You need USB support, if you have an USB input device. Also you need to activate the following kernel options:

KERNEL PS/2 keyboard/mouse support

Device Drivers  --->
    Input device support  --->
        <*>   Event interface
        [*]   Mice  --->
              <*>   PS/2 mouse
        -*-   Keyboards  --->
              <*>   AT keyboard

KERNEL USB input device support

Device Drivers  --->
    HID support  --->
        <*> HID bus support
        <*> Generic HID driver
            USB HID support  --->
                <*> USB HID transport layer

Some USB mice (e.g. Logitech G5 and Razer Naga 2014) additionally need the following option:

KERNEL Improved transaction support

Device Drivers  --->
    [*] USB support  --->
        [*]   Improved Transaction Translator scheduling

Driver

FILE /etc/portage/make.confSet INPUT_DEVICES

INPUT_DEVICES="evdev"

After setting the INPUT_DEVICES variable remember to update the system using the following command so the changes take effect:

root #emerge --ask --changed-use --deep @world

Configuration

Keyboard layout

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:

root #cp /usr/share/X11/xorg.conf.d/10-evdev.conf /etc/X11/xorg.conf.d/

FILE /etc/X11/xorg.conf.d/10-evdev.conf

Section "InputClass"
        Identifier "evdev keyboard catchall"
        ...
        Driver "evdev"
        Option "xkb_layout" "de"
EndSection

For more info please read the Configuring the keyboard.