[Nix-dev] displaymanager: gdm broken?

[Roland Koebler]

Hi,

if I chose gdm as display-manger in NixOS, gdm fails to show a
login-screen. Is this a known bug and is there a solution or
workaround?

Chosing slim or lightdm as display-manager works (but slim is *really*
user-unfriendly when using different sessions/windowmanagers, since
it shows the selected session as white text on nearly-white background
and does not tell you how to select which session to use).

Details:

- /etc/nixos/configuration.nix:

services.xserver.displayManager.gdm.enable = true;

- Then:

# nixos-rebuild switch
# systemctl restart display-manager.service

- Afterwards, nothing seems to happen; tty1..tty6 all show a text-login-
prompt. gdm is running, but no X11/login-screen is shown.

- # systemctl status display-manager.service

display-manager.service - X11 Server
Loaded: loaded (/nix/store/vpyvxzznl4b7s2sbfgz7daaw0jmj0hb3-unit-display-manager.service/display-manager.service; linked; vendor preset: enabled)
Active: active (running) since Mon 2017-06-19 15:49:30 CEST; 1min 45s ago
Process: 22160 ExecStartPre=/nix/store/k3ahl02n8pw0cpa4dahmi25jwfzrga7v-unit-script/bin/display-manager-pre-start (code=exited, status=0/SUCCESS)
Main PID: 22163 (gdm)
Tasks: 6 (limit: 4915)
CGroup: /system.slice/display-manager.service
├─22163 /nix/store/nq1wc8kbl7r68d7kq5yh8giwv5h8r86s-gdm-3.22.0/bin/gdm
└─22168 gdm-session-worker [pam/gdm-launch-environment]

Jun 19 15:49:30 rala systemd[1]: Stopped X11 Server.
Jun 19 15:49:30 rala systemd[1]: Starting X11 Server...
Jun 19 15:49:30 rala systemd[1]: Started X11 Server.
Jun 19 15:49:30 rala gdm[22163]: Failed to list cached users: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.Accounts was not provided by any .service files

- ps x | grep gdm

22163 ? Ssl 0:00 /nix/store/nq1wc8kbl7r68d7kq5yh8giwv5h8r86s-gdm-3.22.0/bin/gdm
22168 ? Sl 0:00 gdm-session-worker [pam/gdm-launch-environment]


thanks
Roland

[Laverne Schrock]

Post by Roland Koebler
Hi,
if I chose gdm as display-manger in NixOS, gdm fails to show a
login-screen. Is this a known bug and is there a solution or
workaround?
Chosing slim or lightdm as display-manager works (but slim is
*really*
user-unfriendly when using different sessions/windowmanagers, since
it shows the selected session as white text on nearly-white
background
and does not tell you how to select which session to use).
    services.xserver.displayManager.gdm.enable = true;
  # nixos-rebuild switch
  # systemctl restart display-manager.service
- Afterwards, nothing seems to happen; tty1..tty6 all show a text-
login-
  prompt. gdm is running, but no X11/login-screen is shown.
- # systemctl status display-manager.service
 
  display-manager.service - X11 Server
     Loaded: loaded (/nix/store/vpyvxzznl4b7s2sbfgz7daaw0jmj0hb3-
unit-display-manager.service/display-manager.service; linked; vendor
preset: enabled)
     Active: active (running) since Mon 2017-06-19 15:49:30 CEST;
1min 45s ago
    Process: 22160
ExecStartPre=/nix/store/k3ahl02n8pw0cpa4dahmi25jwfzrga7v-unit-
script/bin/display-manager-pre-start (code=exited, status=0/SUCCESS)
   Main PID: 22163 (gdm)
      Tasks: 6 (limit: 4915)
     CGroup: /system.slice/display-manager.service
             ├─22163 /nix/store/nq1wc8kbl7r68d7kq5yh8giwv5h8r86s-gdm-
3.22.0/bin/gdm
             └─22168 gdm-session-worker [pam/gdm-launch-environment]
  Jun 19 15:49:30 rala systemd[1]: Stopped X11 Server.
  Jun 19 15:49:30 rala systemd[1]: Starting X11 Server...
  Jun 19 15:49:30 rala systemd[1]: Started X11 Server.
GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name
org.freedesktop.Accounts was not provided by any .service files
- ps x | grep gdm
  22163 ?        Ssl    0:00
/nix/store/nq1wc8kbl7r68d7kq5yh8giwv5h8r86s-gdm-3.22.0/bin/gdm
  22168 ?        Sl     0:00 gdm-session-worker [pam/gdm-launch-
environment]
 
thanks
Roland

`nix-rebuild switch` has been kind of flakey for me since I switched to
GDM (which was also when I switched 
to 17.03). A reboot is usually needed for my system to get X11 back.