[regression] Login screen flickers to black a few times on boot and then finally settles on using Xorg instead of Wayland. No Wayland login option.

[Daniel van Vugt]

https://gitlab.gnome.org/GNOME/mutter/issues/264

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The cosmic login screen flickers to black a few times on boot and then finally settles on using Xorg instead of Wayland.

I can tell because from ssh user 'gdm' is running:

/usr/lib/xorg/Xorg vt2 -displayfd 3 -auth /run/user/121/gdm/Xauthority -background none -noreset -keeptty -verbose 3

and not the usual Xwayland. Also the login screen offers no choice of Xorg or Wayland sessions.

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: gdm3 3.29.91-1ubuntu1
ProcVersionSignature: Ubuntu 4.17.0-6.7-generic 4.17.9
Uname: Linux 4.17.0-6-generic x86_64
ApportVersion: 2.20.10-0ubuntu7
Architecture: amd64
Date: Tue Aug 14 11:41:31 2018
InstallationDate: Installed on 2018-05-26 (79 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Alpha amd64 (20180525)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_AU.UTF-8
 SHELL=/bin/bash
SourcePackage: gdm3
UpgradeStatus: No upgrade log present (probably fresh install)

[Daniel van Vugt (vanvugt)]

In both cases I see:

Aug 14 11:40:46 kab gnome-shell[890]: X Wayland crashed; exiting

Aug 14 11:49:16 kab gnome-shell[890]: X Wayland crashed; exiting

which would explain why the Wayland option is missing when I finally get a login screen.

Unfortunately there are no crash files or core dumps :(

[Iain Lane (laney)]

Please could you file upstream? Ray landed some re-working of VT handling and the lifecycle of the GDM greeter and it's possible some bugs still exist there.

[Daniel van Vugt (vanvugt)]

That probably explains bug 1786872 more than this one.

I'll try collecting some more information first, especially since XWayland not leaving core files is a mutter fix I already own.

[Iain Lane (laney)]

If you file it, the output in the journal might already indicate a problem that can be fixed.

If you don't, no fix will happen.

[Daniel van Vugt (vanvugt)]

Downgrading to gdm3 3.29.90 somewhat avoided the problem and reverted to bug 1786872. But when VT switching to work around that one I managed to reproduce this crash again, even with gdm3 3.29.90-2ubuntu1.

Finally got a crash report from Xwayland this time -> bug 1786914

[Daniel van Vugt (vanvugt)]

And another log. I think grepping for the gnome-shell PID that owned the failed Xwayland instance might be a helpful way to read the logs...

Aug 14 17:29:17 kab /usr/lib/gdm3/gdm-wayland-session[870]: gnome-session-binary[876]: DEBUG(+): GsmAutostartApp: started pid:886
Aug 14 17:29:17 kab gnome-session-binary[876]: DEBUG(+): GsmAutostartApp: started pid:886
Aug 14 17:29:17 kab gnome-shell[886]: Failed to apply DRM plane transform 0: Permission denied
Aug 14 17:29:17 kab gnome-shell[886]: WL: error in client communication (pid 886)
Aug 14 17:29:17 kab org.gnome.Shell.desktop[886]: (EE)
Aug 14 17:29:17 kab org.gnome.Shell.desktop[886]: Fatal server error:
Aug 14 17:29:17 kab org.gnome.Shell.desktop[886]: (EE) wl_drm@4: error 0: authenicate failed
Aug 14 17:29:17 kab org.gnome.Shell.desktop[886]: (EE)
Aug 14 17:29:18 kab gnome-shell[886]: X Wayland crashed; exiting
Aug 14 17:29:18 kab /usr/lib/gdm3/gdm-wayland-session[870]: gnome-session-binary[876]: DEBUG(+): GsmAutostartApp: (pid:886) done (status:1)
Aug 14 17:29:18 kab gnome-session-binary[876]: DEBUG(+): GsmAutostartApp: (pid:886) done (status:1)

[Daniel van Vugt (vanvugt)]

Upstream:
https://gitlab.gnome.org/GNOME/mutter/issues/264

[Daniel van Vugt (vanvugt)]

This patch seems to fix it:
https://gitlab.gnome.org/GNOME/gdm/merge_requests/32

[Daniel van Vugt (vanvugt)]

gdm3 (3.30.0-0ubuntu1) cosmic; urgency=medium

  * Updated to 3.30.0 release:
    - build fixes
    - search for sessions in XDG_DATA_DIRS
    - blacklist some more wayland unfriendly hardware
    - initial setup fix
    - flicker fix
    - misc bug fixes
  * debian/gdm3.install:
    - install udev rules in the correct folder (following upstream build
      fixes)

 -- Didier Roche <email address hidden> Wed, 05 Sep 2018 11:20:11 +0200