The upstream session files display managers use have no concept of sessions being composed from
desktop manager and window manager. To be able to set upstream session files as default
session, we need a single option. Having two different ways to set default session would be confusing,
though, so we decided to deprecate the old method.
We also created separate script for each session, just like we already had a separate desktop
file for each one, and started using displayManager.sessionPackages mechanism to make the
session handling more uniform.
There's two ways of providing graphical sessions now:
- `displayManager.session` via. `desktopManager.session` and
`windowManager.session`
- `displayManager.sessionPackages`
`sessionPackages` doesn't make a distinction between desktop and window
managers. This makes selecting a session provided by a package using
`desktopManager.default` nonsensical.
We therefor introduce `displayManager.defaultSession` which can select a session
from either `displayManager.session` or `displayManager.sessionPackages`.
It will default to `desktopManager.default + windowManager.default` as before.
If the dm default is "none" it will select the first provided session from
`sessionPackages`.
A centralized list for these renames is not good because:
- It breaks disabledModules for modules that have a rename defined
- Adding/removing renames for a module means having to find them in the
central file
- Merge conflicts due to multiple people editing the central file
Previously, if you, for example, set
services.xserver.displayManager.sddm.enable, but forgot to set
services.xserver.enable, you would get an error message that looked like
this:
error: attribute 'display-manager' missing
Which was not particularly helpful.
Using assertions, we can make this message much better.
Switch from slim to lightdm as the display-manager.
If plasma5 is used as desktop-manager use sdddm.
If gnome3 is used as desktop-manager use gdm.
Based on #12516
This makes it easier to support a wider variety of .desktop session files. In
particular this makes it possible to use both the «legacy» sessions and upstream
session files.
We separate `xsession` into two parts, `xsessionWrapper` and `xsession`.
`xsessionWrapper` sets up the correct environment and then lauches the session's
Exec command (from the .desktop file), falling back to launching the default
window/desktopManager through the `xsession` script (required by at least some
nixos tests).
`xsession` then _only_ handles launching desktop-managers/window-managers defined
through `services.xserver.desktopManager.session`.
Previously, the mkDesktops function produced a flat package containing
session files in the top level. As a preparation for introduction of
Wayland sessions, the files will now be placed to $out/share/xsessions.
This adds configuration options which automate the configuration of NVIDIA Optimus using PRIME. This allows using the NVIDIA proprietary driver on Optimus laptops, in order to render using the NVIDIA GPU while outputting to displays connected only to the integrated Intel GPU. It also adds an option for enabling kernel modesetting for the NVIDIA driver (via a kernel command line flag); this is particularly useful together with Optimus/PRIME because it fixes tearing on PRIME-connected screens.
The user still needs to enable the Optimus/PRIME feature and specify the bus IDs of the Intel and NVIDIA GPUs, but this is still much easier for users and more reliable. The implementation handles both the X configuration file as well as getting display managers to run certain necessary `xrandr` commands just after X has started.
Configuration of commands run after X startup is done using a new configuration option `services.xserver.displayManager.setupCommands`. Support for this option is implemented for LightDM, GDM and SDDM; all of these have been tested with this feature including logging into a Plasma session.
Note: support of `setupCommands` for GDM is implemented by making GDM run the session executable via a wrapper; the wrapper will run the `setupCommands` before execing. This seemed like the simplest and most reliable approach, and solves running these commands both for GDM's X server and user X servers (GDM starts separate X servers for itself and user sessions). An alternative approach would be with autostart files but that seems harder to set up and less reliable.
Note that some simple features for X configuration file generation (in `xserver.nix`) are added which are used in the implementation:
- `services.xserver.extraConfig`: Allows adding arbitrary new sections. This is used to add the Device section for the Intel GPU.
- `deviceSection` and `screenSection` within `services.xserver.drivers`. This allows the nvidia configuration module to add additional contents into the `Device` and `Screen` sections of the "nvidia" driver, and not into such sections for other drivers that may be enabled.
Plugin and QML import paths were previously determined by NIX_PROFILES. Using
PATH instead allows Qt applications to work under nix-shell without further
modification.
The xsession script was called with inconsistent (depending on the
display managers) and wrong parameters. The main reason for this where
the spaces the parameter syntax. In order to fix this the old syntax:
$1 = '<desktop-manager> + <window-manager>'
Will be replaced with a new syntax:
$1 = "<desktop-manager>+<window-manager>"
This assumes that neither "<desktop-manager>" nor "<window-manager>"
contain the "+" character but this shouldn't be a problem.
This patch also fixes the quoting by using double quotes (") instead of
single quotes (') [0].
Last but not least this'll add some comments for the better
understanding of the script.
[0]: https://specifications.freedesktop.org/desktop-entry-spec/latest/ar01s06.html
- As noted on github, GDM needs different parameters for X.
- Making xserverArgs a true list instead of concat-string helps to
filter it and it feels more correct anyway.
- Tested: gdm+gnome, lightdm+gnome. There seems to be no logout option
in gnome, and gdm doesn't offer other sessions, but maybe these are normal.
It was lacking the dbus configuration to bind to
org.freedesktop.DisplayManager, and it was passing fixed TTY/display
numbers to the X server (see 9be012f0d4).
- added numlock on boot switch
- simply add :
services.xserver.displayManager.sddm.autoNumlock = true;
to configuration.nix and sddm will start
with numlock enabled.
These options allow setting the start and stop scripts for the display
manager. Making these configurable is necessary to allow some hardware
configurations. Upstream ships empty scripts by default, anyway.
The most complex problems were from dealing with switches reverted in
the meantime (gcc5, gmp6, ncurses6).
It's likely that darwin is (still) broken nontrivially.
