nixpkgs/nixos/doc/manual/configuration/x-windows.xml
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<chapter xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
version="5.0"
xml:id="sec-x11">
<title>X Window System</title>
<para>
The X Window System (X11) provides the basis of NixOS graphical user
interface. It can be enabled as follows:
<programlisting>
<xref linkend="opt-services.xserver.enable"/> = true;
</programlisting>
The X server will automatically detect and use the appropriate video driver
from a set of X.org drivers (such as <literal>vesa</literal> and
<literal>intel</literal>). You can also specify a driver manually, e.g.
<programlisting>
<xref linkend="opt-services.xserver.videoDrivers"/> = [ "r128" ];
</programlisting>
to enable X.orgs <literal>xf86-video-r128</literal> driver.
</para>
<para>
You also need to enable at least one desktop or window manager. Otherwise,
you can only log into a plain undecorated <command>xterm</command> window.
Thus you should pick one or more of the following lines:
<programlisting>
<xref linkend="opt-services.xserver.desktopManager.plasma5.enable"/> = true;
<xref linkend="opt-services.xserver.desktopManager.xfce.enable"/> = true;
<xref linkend="opt-services.xserver.desktopManager.gnome3.enable"/> = true;
<xref linkend="opt-services.xserver.desktopManager.mate.enable"/> = true;
<xref linkend="opt-services.xserver.windowManager.xmonad.enable"/> = true;
<xref linkend="opt-services.xserver.windowManager.twm.enable"/> = true;
<xref linkend="opt-services.xserver.windowManager.icewm.enable"/> = true;
<xref linkend="opt-services.xserver.windowManager.i3.enable"/> = true;
<xref linkend="opt-services.xserver.windowManager.herbstluftwm.enable"/> = true;
</programlisting>
</para>
<para>
NixOSs default <emphasis>display manager</emphasis> (the program that
provides a graphical login prompt and manages the X server) is LightDM. You
can select an alternative one by picking one of the following lines:
<programlisting>
<xref linkend="opt-services.xserver.displayManager.sddm.enable"/> = true;
<xref linkend="opt-services.xserver.displayManager.gdm.enable"/> = true;
</programlisting>
</para>
<para>
You can set the keyboard layout (and optionally the layout variant):
<programlisting>
<xref linkend="opt-services.xserver.layout"/> = "de";
<xref linkend="opt-services.xserver.xkbVariant"/> = "neo";
</programlisting>
</para>
<para>
The X server is started automatically at boot time. If you dont want this
to happen, you can set:
<programlisting>
<xref linkend="opt-services.xserver.autorun"/> = false;
</programlisting>
The X server can then be started manually:
<screen>
<prompt># </prompt>systemctl start display-manager.service
</screen>
</para>
<para>
On 64-bit systems, if you want OpenGL for 32-bit programs such as in Wine,
you should also set the following:
<programlisting>
<xref linkend="opt-hardware.opengl.driSupport32Bit"/> = true;
</programlisting>
</para>
<simplesect xml:id="sec-x11-auto-login">
<title>Auto-login</title>
<para>
The x11 login screen can be skipped entirely, automatically logging you into
your window manager and desktop environment when you boot your computer.
</para>
<para>
This is especially helpful if you have disk encryption enabled. Since you
already have to provide a password to decrypt your disk, entering a second
password to login can be redundant.
</para>
<para>
To enable auto-login, you need to define your default window manager and
desktop environment. If you wanted no desktop environment and i3 as your your
window manager, you'd define:
<programlisting>
<xref linkend="opt-services.xserver.displayManager.defaultSession"/> = "none+i3";
</programlisting>
Every display manager in NixOS supports auto-login, here is an example
using lightdm for a user <literal>alice</literal>:
<programlisting>
<xref linkend="opt-services.xserver.displayManager.lightdm.enable"/> = true;
<xref linkend="opt-services.xserver.displayManager.autoLogin.enable"/> = true;
<xref linkend="opt-services.xserver.displayManager.autoLogin.user"/> = "alice";
</programlisting>
</para>
</simplesect>
<simplesect xml:id="sec-x11--graphics-cards-intel">
<title>Intel Graphics drivers</title>
<para>
There are two choices for Intel Graphics drivers in X.org:
<literal>modesetting</literal> (included in the <package>xorg-server</package> itself)
and <literal>intel</literal> (provided by the package <package>xf86-video-intel</package>).
</para>
<para>
The default and recommended is <literal>modesetting</literal>.
It is a generic driver which uses the kernel
<link xlink:href="https://en.wikipedia.org/wiki/Mode_setting">mode setting</link>
(KMS) mechanism. It supports Glamor (2D graphics acceleration via OpenGL)
and is actively maintained but may perform worse in some cases (like in old chipsets).
</para>
<para>
The second driver, <literal>intel</literal>, is specific to Intel GPUs,
but not recommended by most distributions: it lacks several modern features
(for example, it doesn't support Glamor) and the package hasn't been officially
updated since 2015.
</para>
<para>
The results vary depending on the hardware, so you may have to try both drivers.
Use the option <xref linkend="opt-services.xserver.videoDrivers"/> to set one.
The recommended configuration for modern systems is:
<programlisting>
<xref linkend="opt-services.xserver.videoDrivers"/> = [ "modesetting" ];
<xref linkend="opt-services.xserver.useGlamor"/> = true;
</programlisting>
If you experience screen tearing no matter what, this configuration was
reported to resolve the issue:
<programlisting>
<xref linkend="opt-services.xserver.videoDrivers"/> = [ "intel" ];
<xref linkend="opt-services.xserver.deviceSection"/> = ''
Option "DRI" "2"
Option "TearFree" "true"
'';
</programlisting>
Note that this will likely downgrade the performance compared to
<literal>modesetting</literal> or <literal>intel</literal> with DRI 3 (default).
</para>
</simplesect>
<simplesect xml:id="sec-x11-graphics-cards-nvidia">
<title>Proprietary NVIDIA drivers</title>
<para>
NVIDIA provides a proprietary driver for its graphics cards that has better
3D performance than the X.org drivers. It is not enabled by default because
its not free software. You can enable it as follows:
<programlisting>
<xref linkend="opt-services.xserver.videoDrivers"/> = [ "nvidia" ];
</programlisting>
Or if you have an older card, you may have to use one of the legacy drivers:
<programlisting>
<xref linkend="opt-services.xserver.videoDrivers"/> = [ "nvidiaLegacy390" ];
<xref linkend="opt-services.xserver.videoDrivers"/> = [ "nvidiaLegacy340" ];
<xref linkend="opt-services.xserver.videoDrivers"/> = [ "nvidiaLegacy304" ];
<xref linkend="opt-services.xserver.videoDrivers"/> = [ "nvidiaLegacy173" ];
</programlisting>
You may need to reboot after enabling this driver to prevent a clash with
other kernel modules.
</para>
</simplesect>
<simplesect xml:id="sec-x11--graphics-cards-amd">
<title>Proprietary AMD drivers</title>
<para>
AMD provides a proprietary driver for its graphics cards that has better 3D
performance than the X.org drivers. It is not enabled by default because
its not free software. You can enable it as follows:
<programlisting>
<xref linkend="opt-services.xserver.videoDrivers"/> = [ "ati_unfree" ];
</programlisting>
You will need to reboot after enabling this driver to prevent a clash with
other kernel modules.
</para>
<note>
<para>
For recent AMD GPUs you most likely want to keep either the defaults
or <literal>"amdgpu"</literal> (both free).
</para>
</note>
</simplesect>
<simplesect xml:id="sec-x11-touchpads">
<title>Touchpads</title>
<para>
Support for Synaptics touchpads (found in many laptops such as the Dell
Latitude series) can be enabled as follows:
<programlisting>
<xref linkend="opt-services.xserver.libinput.enable"/> = true;
</programlisting>
The driver has many options (see <xref linkend="ch-options"/>). For
instance, the following disables tap-to-click behavior:
<programlisting>
<xref linkend="opt-services.xserver.libinput.tapping"/> = false;
</programlisting>
Note: the use of <literal>services.xserver.synaptics</literal> is deprecated
since NixOS 17.09.
</para>
</simplesect>
<simplesect xml:id="sec-x11-gtk-and-qt-themes">
<title>GTK/Qt themes</title>
<para>
GTK themes can be installed either to user profile or system-wide (via
<literal>environment.systemPackages</literal>). To make Qt 5 applications
look similar to GTK2 ones, you can install <literal>qt5.qtbase.gtk</literal>
package into your system environment. It should work for all Qt 5 library
versions.
</para>
</simplesect>
<simplesect xml:id="custom-xkb-layouts">
<title>Custom XKB layouts</title>
<para>
It is possible to install custom
<link xlink:href="https://en.wikipedia.org/wiki/X_keyboard_extension">
XKB
</link>
keyboard layouts using the option
<option>
<link linkend="opt-services.xserver.extraLayouts">
services.xserver.extraLayouts
</link>
</option>.
As a first example, we are going to create a layout based on the basic US
layout, with an additional layer to type some greek symbols by pressing the
right-alt key.
</para>
<para>
To do this we are going to create a <literal>us-greek</literal> file
with a <literal>xkb_symbols</literal> section.
</para>
<programlisting>
xkb_symbols &quot;us-greek&quot;
{
include &quot;us(basic)&quot; // includes the base US keys
include &quot;level3(ralt_switch)&quot; // configures right alt as a third level switch
key &lt;LatA&gt; { [ a, A, Greek_alpha ] };
key &lt;LatB&gt; { [ b, B, Greek_beta ] };
key &lt;LatG&gt; { [ g, G, Greek_gamma ] };
key &lt;LatD&gt; { [ d, D, Greek_delta ] };
key &lt;LatZ&gt; { [ z, Z, Greek_zeta ] };
};
</programlisting>
<para>
To install the layout, the filepath, a description and the list of
languages must be given:
</para>
<programlisting>
<xref linkend="opt-services.xserver.extraLayouts"/>.us-greek = {
description = "US layout with alt-gr greek";
languages = [ "eng" ];
symbolsFile = /path/to/us-greek;
}
</programlisting>
<note>
<para>
The name should match the one given to the
<literal>xkb_symbols</literal> block.
</para>
</note>
<para>
The layout should now be installed and ready to use: try it by
running <literal>setxkbmap us-greek</literal> and type
<literal>&lt;alt&gt;+a</literal>. To change the default the usual
<option>
<link linkend="opt-services.xserver.layout">
services.xserver.layout
</link>
</option>
option can still be used.
</para>
<para>
A layout can have several other components besides
<literal>xkb_symbols</literal>, for example we will define new
keycodes for some multimedia key and bind these to some symbol.
</para>
<para>
Use the <emphasis>xev</emphasis> utility from
<literal>pkgs.xorg.xev</literal> to find the codes of the keys of
interest, then create a <literal>media-key</literal> file to hold
the keycodes definitions
</para>
<programlisting>
xkb_keycodes &quot;media&quot;
{
&lt;volUp&gt; = 123;
&lt;volDown&gt; = 456;
}
</programlisting>
<para>
Now use the newly define keycodes in <literal>media-sym</literal>:
</para>
<programlisting>
xkb_symbols &quot;media&quot;
{
key.type = &quot;ONE_LEVEL&quot;;
key &lt;volUp&gt; { [ XF86AudioLowerVolume ] };
key &lt;volDown&gt; { [ XF86AudioRaiseVolume ] };
}
</programlisting>
<para>
As before, to install the layout do
</para>
<programlisting>
<xref linkend="opt-services.xserver.extraLayouts"/>.media = {
description = "Multimedia keys remapping";
languages = [ "eng" ];
symbolsFile = /path/to/media-key;
keycodesFile = /path/to/media-sym;
};
</programlisting>
<note>
<para>
The function <literal>pkgs.writeText &lt;filename&gt; &lt;content&gt;
</literal> can be useful if you prefer to keep the layout definitions
inside the NixOS configuration.
</para>
</note>
<para>
Unfortunately, the Xorg server does not (currently) support setting a
keymap directly but relies instead on XKB rules to select the matching
components (keycodes, types, ...) of a layout. This means that components
other than symbols won't be loaded by default. As a workaround, you
can set the keymap using <literal>setxkbmap</literal> at the start of the
session with:
</para>
<programlisting>
<xref linkend="opt-services.xserver.displayManager.sessionCommands"/> = "setxkbmap -keycodes media";
</programlisting>
<para>
If you are manually starting the X server, you should set the argument
<literal>-xkbdir /etc/X11/xkb</literal>, otherwise X won't find your layout files.
For example with <command>xinit</command> run
<screen><prompt>$ </prompt>xinit -- -xkbdir /etc/X11/xkb</screen>
</para>
<para>
To learn how to write layouts take a look at the XKB
<link xlink:href="https://www.x.org/releases/current/doc/xorg-docs/input/XKB-Enhancing.html#Defining_New_Layouts">
documentation
</link>. More example layouts can also be found
<link xlink:href="https://wiki.archlinux.org/index.php/X_KeyBoard_extension#Basic_examples">
here
</link>.
</para>
</simplesect>
</chapter>