Philipp Burch's questions

it seems to be a "once again" issue, but I really wasn't able to find anything useful for my case in the web.

Background:

I have a Lenovo Thinkpad T480, on which I installed Ubuntu 18.04 right after unpacking. The preinstalled Windows didn't even finish the installation/setup then. I bought it actually because it has switchable graphics (NVIDIA dedicated graphics and Intel integrated graphics), which allows me to run the 3D CAD (in a VMware VM with Windows) also when on the go.

I first didn't configure any power saving stuff at all, which led to a short battery runtime of maybe 1.5h or something. So about a month back, I installed tlp and also gave bumblebee a try, to make use of the Optimus feature (dynamic switching between integrated and dedicated graphics). This didn't work at all, the CAD could not use the 3D acceleration and resuming after suspend tended to crash the system or cause weird effects. One such weird effect was a USB port malfunction, so that the plugged-in mouse did not work anymore (no power). Integrated devices such as keyboard and touchpad still worked though. A reboot "fixed" the problem, so it probably is not hardware-related. I removed bumblebee shortly afterwards.

I usually completely reboot/turn off the notebook once in a few days, otherwise I just put it to sleep.

Problem:

A few days back, I shut down the notebook as usual. After booting it up next time to the login screen, the problem first appeared: I could enter my password, hit Enter and all that happens is the screen turning black, the mouse pointer is displayed near the lower right corner of the screen and after a second or so, I'm back at the login screen. No error message. At least once it also happened that the USB port problem described above showed up again.

It was always possible to login to a terminal (Ctrl+Alt+F2) without any trouble.

What I've tried:

Especially due to the mentioned USB problem, I suspected the graphics driver to have something to do with it. So I uninstalled all NVIDIA-related packages, but the problem remained the same. Reinstalling did not change anything either. I also tried to install and uninstall (with a few reboots) tlp and bumblebee, but none of them seem to change anything at all.

Booting into a previous kernel version did not help.

I went to a terminal and installed Xubuntu-desktop. Now, when I boot the computer, select a Xubuntu or Xfce session, then I can login to the graphical desktop and everything runs as well. Including 3D acceleration and NVIDIA-prime. This is true no matter if I use gdm3 or lightdm as display manager.

If I select any of the other sessions (GNOME classic, Ubuntu, Ubuntu on Wayland, etc.), the behavior is the same as before: Black screen, mouse pointer, sometimes a short flash of the desktop background image, then back at the login screen. Interestingly, if I now switch back to a Xubuntu session, the login fails there as well, with the same symptoms. Only after a reboot does such a login work again. Just on my last try, this led to apport coming up with a crash of light-locker:

light-locker crashed with signal 5 in g_type_create_instance()

Logs:

I really don't know where to look for errors. I've checked a few places:

• /var/log/Xorg.*.log: No errors (EE), nothing suspicous.
• ~/.xsession-errors: Last update is from a week back. A lot of errors are reported relating to tracker not being able to insert some metadata, as well as from the theme parser. At the end of the file, there are many such messages: Gtk-CRITICAL **: 12:49:52.203: gtk_widget_destroy: assertion ' GTK_IS_WIDGET (widget)' failed

And:

Gdk-Message: 12:51:24.605: nm-applet: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.

Gdk-Message: 12:51:24.605: update-notifier: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.

Gdk-Message: 12:51:24.608: blueman-applet: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.0.

Gdk-Message: 12:51:24.630: polkit-gnome-authentication-agent-1: Fatal IO error 0 (Success) on X server :0.0.

• /var/log/lightdm/lightdm.log.1.gz: Lots of DEBUG messages, otherwise nothing more serious than WARNING: Seat type 'xlocal' is deprecated, use 'type=local' instead

• /var/log/lightdm/seat0-greeter.log.1.gz: Lots of (lightdm-gtk-greeter:1447): Gtk-WARNING **: 16:51:55.144: Drawing a gadget with negative dimensions. Did you forget to allocate a size? (node menubar owner GreeterMenuBar) messages. Some more suspicous ones: Gdk-Message: 11:06:44.240: lightdm-gtk-greeter: Fatal IO error 11 (Resource temporarily unavailable) on X server :0., Gdk-Message: 12:57:34.520: lightdm-gtk-greeter: Fatal IO error 4 (Interrupted system call) on X server :0.

• journalctl: Maybe a hint related to the light-locker crash: light-locker[2482]: Environment variable XDG_SESSION_PATH not set. Is LightDM running? A message from X: (EE) open /dev/fb0: Permission denied A kernel message, which I sometimes also see flashing on the screen when it switches some mode: kernel: acpi INT3400:00: Unsupported event [0x88]

System:

$ uname -a
Linux phiptp480 4.15.0-45-generic #48-Ubuntu SMP Tue Jan 29 16:28:13 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux`
$ cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=18.04
DISTRIB_CODENAME=bionic
DISTRIB_DESCRIPTION="Ubuntu 18.04.1 LTS"

Questions:

• What could be the cause for this behavior?
• Where should I look for hints about this case?
• How can I fix the system, except for a full reinstall?

Thanks! Best regards,

Philipp

after installing Ubuntu 18.04 (fresh install, no upgrade), I spent some time to get a workspace grid with my previous keyboard shortcuts working (see Workspace layout in Ubuntu 18.04 [duplicate] and Ubuntu 18.04: Put window into screen corner).

This basically works fine, but it interferes with the keyboard shortcuts to split the view ("Maximize window", "Restore window", "View split on left", "View split on right") using the Super+Arrow key combinations.

When setting my shortcuts, these are replaced and everything is fine. But after a reboot, the view splitting shortcuts are set again and lead to keybinding conflicts (e.g. Super+Up is now set to "Move to workspace above" AND to "Maximize window"). The view splitting shortcuts then usually take precedence, so if I want to switch to another workspace, the window is modified instead.

What could be reason for this restoring of original keybindings and how can I avoid it?

Thanks!

I have an external 4K display on my laptop with plenty of space, that I usually use like four individual monitors in a grid. So I tend to put one window in every corner of the screen (IDE, terminal, browser, etc.). In Ubuntu 16.04, Unity offered to option to automatically place windows there by moving them to the screen edge or screen corner, so you had 8 options on where to put a window just by moving it around (top left corner, top half, top right corner, right half, etc.). Now in Ubuntu 18.04, only the Windows-like behaviour seems to be implemented with maximize (top edge), left half (left edge) and right half (right edge). Is there a way to get the additional areas back as in Unity?

Thanks!

Best regards, Philipp