Score:0

Login Screen Issue: First lightdm needs to be killed to get X session to work

bo flag

I'm running MATE 20.04 and have a problem each time I reboot. Instead of getting the lightdm login screen

  1. When I have the grub option "silent" set I get a blank screen (it's all black but on)
  2. When I remove the silent option, I get the following messages
    Loading, please wait..
    Starting version 245.4_ubuntu3.11
    Begin: Loading essential drivers ... done.
    Begin: Running /scripts/init-premount
    
    The screen goes blank and then redisplays the above messages

At this point, if I try to get to a local term (Ctl-Fn-F1), I have no luck. However if I ssh into the machine and kill lightdm, the login screen appears. Here's some more details

  > [machine ~] $ ps aux |grep lightdm
  > root        1173  0.0  0.0 232332  7484 ?        Ssl  14:45   0:00 /usr/sbin/lightdm
  > root        1225  0.2  0.6 1346752 67728 tty7    Ssl+ 14:45   0:00 /usr/lib/xorg/Xorg -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
  > user1       1854  0.0  0.0   9032   724 pts/0    S+   14:46   0:00 grep lightdm
  > [machine ~] $ sudo kill 1173
  > [sudo] password for user1:
  > [machine ~] $ ps aux |grep lightdm
  > root        1925  0.4  0.0 232332  7328 ?        Ssl  14:47   0:00 /usr/sbin/lightdm
  > root        1930 12.8  0.9 1497312 96312 tty7    Ssl+ 14:47   0:00 /usr/lib/xorg/Xorg -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
  > root        1955  0.2  0.0 159972  8236 ?        Sl   14:47   0:00 lightdm --session-child 17 20
  > lightdm     1959  5.0  0.0  18836  9948 ?        Ss   14:47   0:00 /lib/systemd/systemd --user
  > lightdm     1960  0.0  0.0 169680  4188 ?        S    14:47   0:00 (sd-pam)
  > lightdm     1969  4.0  0.1 358024 18308 ?        S<sl 14:47   0:00 /usr/bin/pulseaudio --daemonize=no --log-target=journal
  > lightdm     1972  0.0  0.0 166156  4764 ?        Sl   14:47   0:00 /usr/bin/gnome-keyring-daemon --daemonize --login
  > lightdm     1975  0.0  0.0   2608   540 ?        Ss   14:47   0:00 /bin/sh /usr/lib/lightdm/lightdm-greeter-session /usr/sbin/slick-greeter
  > lightdm     1976 25.2  0.4 601636 48404 ?        Sl   14:47   0:01 /usr/sbin/slick-greeter
  > lightdm     1977  0.5  0.0   7464  4608 ?        Ss   14:47   0:00 /usr/bin/dbus-daemon --session --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only
  > lightdm     1983  0.0  0.0 156092  5376 ?        Sl   14:47   0:00 /usr/libexec/dconf-service
  > lightdm     2011  0.0  0.0 305748  6592 ?        Sl   14:47   0:00 /usr/libexec/at-spi-bus-launcher --launch-immediately
  > lightdm     2016  0.0  0.0   7332  4144 ?        S    14:47   0:00 /usr/bin/dbus-daemon --config-file=/usr/share/defaults/at-spi2/accessibility.conf --nofork --print-address 3
  > lightdm     2017  0.0  0.0 239704  7512 ?        Ssl  14:47   0:00 /usr/libexec/gvfsd
  > lightdm     2022  0.0  0.0 312800  6144 ?        Sl   14:47   0:00 /usr/libexec/gvfsd-fuse /run/user/110/gvfs -f -o big_writes
  > root        2056  0.0  0.0  12560  6200 ?        S    14:47   0:00 lightdm --session-child 13 20
  > lightdm     2058  0.5  0.0 162828  7668 ?        Sl   14:47   0:00 /usr/libexec/at-spi2-registryd --use-gnome-session
  > user1       2064  0.0  0.0   9032   664 pts/0    S+   14:47   0:00 grep lightdm

Another 'fix' is to boot into safe mode then continue on via the 'resume' option. The login shows up no problemo.

First, what's going on?

Second, why can't I access the terms via Ctl-Fn-F1?

Much obliged.

UPDATES:

  • Using 'nomodeset' when booting the kernel avoids the problem.
    • This argument is also used in recovery mode and would explain why that method works
    • Unfortunately, I get a black screen when I resume from sleep if I use this 'solution'
  • Getting notifications about not finding my external display
    • Tried booting with an external display plugged in and I get the login screen using the default settings (I don't need to use nomodeset)
    • Need to see if resume works next.
    • It seems like there's an issue with the login screen if I used an external monitor in the previous session. I suspect this means it's looking for the second display, can't find it and so it hangs.
Score:0
bo flag

Okay, after many hours of rebooting, sshing in and restarting lightdm, then trying something else, I believe I have a solution!

There seem to be 2 issues with the solutions given here: https://wiki.archlinux.org/title/LightDM

  1. Problem: "LightDM service is started before your graphics drivers are properly loaded"

    Solution: Created /etc/lightdm/lightdm.conf.d/50-logind-check.conf with the following lines

    [LightDM]
    logind-check-graphical=true
    
  2. Problem: LightDM was trying to use the unattached external screen instead of the builtin screen.

    Solution: Forced it to use the primary screen at eDP by creating /etc/lightdm/lightdm.d/lightdm.conf with the line

    display-setup-script=xrandr --output eDP --primary
    
mangohost

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.