Bug#1120609: gdm3 fails to start after upgrade to 49.1-6

[Brent S. Elmer, Ph.D.]

I finally had some time to experiment.  I already had nvidia-
drm.modeset=1 on my grub command line.  I commented WaylandEnable=false
in /etc/gdm3/daemon.conf.
I have 2 4k monitors.  I have scaling set to 100% on both monitors and
font scaling to 1.70 in gnome tweaks.

Here are the issues I have with gnome under wayland.
1. When I log in to gnome, only one of the 2 monitors shows up.  It
appears to be random which one it is.  The other one gets no signal. If
the monitor specified as the primary display and I have it set to only
show the top bar and activities on the primary display, I cannot do
much.  I have to right click on the desktop to get to displays.  Both
monitors are marked as being used even though only 1 is showing
anything.  I unmark then apply then mark then apply the monitor that is
not showing.  Then both monitors show up.  By this time, the wrong
monitor shows as primary and I have to fix this also.  This is a major
problem to have to do every time I log in.

2. chromium does not show the min, close icons anymore.  I have to
right click on the chromium title bar to get the min, close options.  I
have found that I can also guess where the icons are and blindly click
them and they work.  This is also not cool.

3. The UI under wayland does not seem as responsive as under xorg
either.

4. When I update to this version of gdm3 and gnome-session, I no longer
have the ability to run gnome under xorg(i.e. the original problem I
reported).  This shows up on the gdm3 select menu as default Xsession
which is what I always used and everything just worked.

A lot of these issues are minor annoyances but the monitor issue is a
major problem for me.


On Thu, 2025-11-13 at 09:57 +0000, Simon McVittie wrote:
> Control: tags -1 + moreinfo
> 
> On Wed, 12 Nov 2025 at 21:38:29 -0600, Brent wrote:
> > gdm3 fails to start after upgrading.  I get the black screen with a
> > blinking
> > cursor in the top left corner.
> 
> We will need more information than this: the same upgrade has worked 
> successfully for others. Please check the systemd Journal for log 
> messages that occur during the failed startup.
> 
> > Kernel: Linux 6.12.48251025 (SMP w/2 CPU threads; PREEMPT)
> > Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_WARN,
> > TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
> 
> This doesn't look like an official Debian kernel, so one possible
> cause 
> is if your (presumably locally-built) kernel doesn't support a
> required 
> feature.
> 
> Is that proprietary/out-of-tree module a version of the Nvidia 
> proprietary driver?  If yes, what version?
> 
> > /etc/gdm3/daemon.conf changed:
> > [daemon]
> > WaylandEnable=false
> 
> GNOME 49 only supports Wayland sessions. gdm3 can still launch X11 
> sessions as the session you log in to (tested with cinnamon), but the
> gdm3 greeter (the login prompt) is now always a Wayland session, and
> so 
> is a GNOME login session.
> 
>      smcv