Re: [gentoo-user] Login manager occasionally fails to show

[Michael <confabulate@kintzios.com>]

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On Sunday 26 January 2025 11:18:00 Greenwich Mean Time Peter Humphrey wrote:
> On Saturday 25 January 2025 21:41:01 Greenwich Mean Time Markus Gustafsson
> 
> wrote:
> > Hi!
> > 
> > I've been running in to a problem on and off for the past year or so: when
> > I boot my computer it won't always show a login screen (SDDM). The screen
> > will remain dark without a signal. If I swap tty with ctrl+alt+F1 it will
> > show me the boot log, with the last entry being "starting local" and
> > letting me login through the terminal. I can then reboot and things will
> > start up just fine. Interestingly it does say something about shutting
> > down the display manager when I reboot in such instances...
> > 
> > I feel like happens if I fail to start my monitor fast enough, but I'm not
> > entirely sure. Could that be related?
> 
> You need your monitor on during startup; the system needs to read EDID from
> it to be able to drive it properly. That could be your problem.

After an SDDM update many months ago I started having SDDM problems similar to 
the OP.  The SDDM display manager GUI would not launch at all - black screen.  
Or, it would launch, but then it would appear to not take my passwd to login.  
Or, it would seemingly login, but end up on a black screen with only a mouse 
cursor and no desktop.  The problem was manifesting whether I was launching an 
X11 or Wayland desktop session.  If I dropped into a console and restarted the 
display-manager service, then SDDM launched and worked normally.  Following a 
reboot the problem of the non-functioning SDDM was present again.

I tried configuring SDDM to use x11, x11-user and wayland (experimental) with 
kwin or weston compositor.  I tried enabling/disabling TPM in the BIOS/kernel.  
Nothing made a difference.  The logs were not very informative to help 
troubleshooting.

This was only happening on one PC which has a new(er), faster CPU.  All older 
and slower CPU PCs exhibited no such behaviour.  I suspected the services were 
starting up too fast and either the haveged service didn't have enough time to 
generate the needed entropy for SDDM, or SDDM was clashing with some other 
service in the startup sequence.

I tried adding some wait directive for the display-manager service, but when 
that did not work I added in /etc/rc.conf:

rc_display_manager_after="local"

to push the display-manager at the end of the queue.  Although SDDM now takes 
a second longer than before to come up, at least SDDM starts and I am able to 
login normally.

HTH.

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