Xfce Forum

bitrat

Member

Registered: 2023-07-19

Posts: 20

my desktop is lost after locking the screen.

UPDATE:

I uninstalled light-locker and replaced it with xscreensaver and can now lock and unlock my desktop using the xflock4 script, which calls xscreensaver-command --lock.

The problem remains if I hibernate the system, so that must be what light-locker was doing. I think it is to do with power manager integration with the video driver, but it's not important for me to hibernate, just to lock, so the primary issue is essentially solved for now.

I may try xfce4-screensaver-command, just out of interest.

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Hi,

I'm trying to solve an issue where my desktop is lost after locking the screen.

After waking and logging back in via the greeter, the XServer is running (there's a mouse pointer and remote X sessions work) but the screen is black and  sometimes the mouse pointer is laggy. 

While the screen is locked, I can see in pstree that there are two Xorg processes.  There are also multiple lightdm --session-child processes. 

Also, the two XServers are using two different VTs.  That could be relevant as I also lose the desktop in exactly the same way if I switch from a working desktop to a different VT (ctrl-alt-f4) then back (ctrl-alt-f7).  (I haven't investigated with pstree in that scenario yet.)

I thought the second XServer might be the problem, but then I saw documentation suggesting it's run for security reasons (I'll update that source here later).  If so, I presume it's required for a screensaver, but it's gone once the greeter is visible.

Tbh, I'm not very au fait with X and I'm not even sure what :0 and :1 actually refer to...  screens? servers?

from pstree -a before screen is locked...

  |-lightdm
  |   |-Xorg :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
  |   |   `-{Xorg}
  |   |-lightdm --session-child 15 26
  |   |   |-xfce4-session
  |   |   .   .
  |   |   .   .
  |   |   .   .
  |   |   |   `-2*[{xfce4-session}]
  |   |   `-2*[{lightdm}]
  |   `-2*[{lightdm}]

while screen is locked...

  |-lightdm
  |   |-Xorg :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
  |   |   `-{Xorg}
  |   |-Xorg :1 -seat seat0 -auth /var/run/lightdm/root/:1 -nolisten tcp vt8 -novtswitch
  |   |   `-{Xorg}
  |   |-lightdm --session-child 15 26
  |   |   |-xfce4-session
  |   |   .   .
  |   |   .   .
  |   |   .   .
  |   |   |   `-2*[{xfce4-session}]
  |   |   `-2*[{lightdm}]
  |   |-lightdm --session-child 21 26
  |   |   |-lightdm-gtk-gre
  |   |   |   `-2*[{lightdm-gtk-gre}]
  |   |   `-2*[{lightdm}]
  |   |-lightdm --session-child 17 31
  |   `-2*[{lightdm}]

after screen is unlocked...

  |-lightdm
  |   |-Xorg :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
  |   |   `-{Xorg}
  |   |-lightdm --session-child 15 26
  |   |   |-xfce4-session
  |   |   .   .
  |   |   |   `-2*[{xfce4-session}]
  |   |   `-2*[{lightdm}]
  |   `-2*[{lightdm}]

This is occurring since I replaced replaced nouveau with the proprietary nvidia driver.  The nouveau driver was dysfunctional and possibly damaging my card.  Following a (possibly misconceived) attempt to remove software dependencies on nouveau I ran apt remove *nouveau* --purge then uninstalled and reinstalled affected graphics programs, including X11.  Apart from the screen lock issue, my system is now running very nicely, so I'm not keen to go back to square one, however I have bought an SSD with the intention of rebuilding on that.  (Off topic, but what is the name of the OS backup app people keep telling me to use?)

FYI: flock4 is calling light-locker-command --lock

Apparently "In the default Debian desktop installation with gnome and gdm3 simply locking the screen won't start extra processes but if you click the "switch user" button in the lock screen gdm3 starts the greeter."

I'd be interested in any lucid explanations of the mechanisms involved and any suggestions for further investigation.  I'm wondering if it has to do with lightdm being unable to access the previous session?  Maybe permissions are involved...?  /var/log/lightdm/*.log doesn't have any obvious clues...

Cheers,
bitrat

Last edited by bitrat (2024-05-01 23:41:19)