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BarthaxFlag for United Kingdom of Great Britain and Northern Ireland

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gdm issue results in black screen during logging out

Using Ubuntu on a family machine.  The machine remains switched on but may not be logged in.  Family members all have separate profiles + the profiles are logged in & out during the day.  We've noticed that after an indeterminate amount of time, the last person to log out will seem to hang during logging out.  It leaves a black screen with the mouse still active but no interaction is possible as there are no controls available.  I've found that if I send gdm a HUP signal, the problem is resolved (note that I have to do this blind-fold as the tty screens never show up once X is started).  I expect that the hang-up signal to gdm isn't going to be the end solution to fixing the issue so I'm trying to understand why this occurs.

I am lucky to have had an ssh session to the machine on one of these occasions, so at the time I took a "ps -ef | grep gdm" output to give me more insight.  As you can see from the output there are some obviously gdmopen processes which look like they are awaiting input...

Note that this is the second time I have asked this question and the solution I accepted first time has not been a full success:

Historical question: https://www.experts-exchange.com/questions/23801061/gdm-issue-results-in-black-screen-during-loggin-out.html
Historical answer:
locate gdm.conf on your machine and make sure it has

[daemon]
AlwaysRestartServer=true
root      8678     1  0 Sep29 ?        00:00:00 gdm
root      8693     1  0 Sep29 ?        00:00:00 /usr/lib/gdm/gdmopen -l /bin/sh -c /usr/bin/whiptail --yesno 'There already appears to be an X server running on display :0.  Should another display number be tried?  Answering no will cause GDM to start the server on :0 again.  (You can change consoles by pressing Ctrl-Alt plus a function key, such as Ctrl-Alt-F7 to go to console 7.  X servers usually run on consoles 7 and higher.)' 16 70
peterm   20623  8678  0 08:03 ?        00:00:00 gdm
root     21275 20623  0 08:35 tty16    00:00:14 /usr/bin/X :0 -br -audit 0 -auth /var/lib/gdm/:0.Xauth -nolisten tcp
peterm   22903 22884  0 15:16 pts/0    00:00:00 grep gdm
root     24153     1  0 Oct01 ?        00:00:00 /usr/lib/gdm/gdmopen -l /bin/sh -c /usr/bin/whiptail --yesno 'There already appears to be an X server running on display :0.  Should another display number be tried?  Answering no will cause GDM to start the server on :0 again.  (You can change consoles by pressing Ctrl-Alt plus a function key, such as Ctrl-Alt-F7 to go to console 7.  X servers usually run on consoles 7 and higher.)' 16 70
root     24413     1  0 Oct05 ?        00:00:00 /usr/lib/gdm/gdmopen -l /bin/sh -c /usr/bin/whiptail --yesno 'There already appears to be an X server running on display :0.  Should another display number be tried?  Answering no will cause GDM to start the server on :0 again.  (You can change consoles by pressing Ctrl-Alt plus a function key, such as Ctrl-Alt-F7 to go to console 7.  X servers usually run on consoles 7 and higher.)' 16 70
root     24440     1  0 Oct05 ?        00:00:00 /usr/lib/gdm/gdmopen -l /bin/sh -c /usr/bin/whiptail --yesno 'There already appears to be an X server running on display :0.  Should another display number be tried?  Answering no will cause GDM to start the server on :0 again.  (You can change consoles by pressing Ctrl-Alt plus a function key, such as Ctrl-Alt-F7 to go to console 7.  X servers usually run on consoles 7 and higher.)' 16 70
root     24442 24440  0 Oct05 tty14    00:00:00 /usr/lib/gdm/gdmopen -l /bin/sh -c /usr/bin/whiptail --yesno 'There already appears to be an X server running on display :0.  Should another display number be tried?  Answering no will cause GDM to start the server on :0 again.  (You can change consoles by pressing Ctrl-Alt plus a function key, such as Ctrl-Alt-F7 to go to console 7.  X servers usually run on consoles 7 and higher.)' 16 70

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gheist
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I remember making historical answer back then.

Does Ctrl-Alt-F1 or Ctrl-Alt-Backspace do anything with black display?

Do you see message from whiptail on your screen? Are you trying to get more users logged in at same time?
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ASKER

Hi ghesit,

Thanks for revisiting. ;)

Oddly enough, this is one of the machines I included in https://www.experts-exchange.com/questions/23934520/Unable-to-view-the-tty-screens-once-X-is-started.html concerning CTRL+ALT+F1. :(

CTRL+ALT+Backspace does appear to affect the situation but does not resolve it: when this scenario happens, the mouse is still active on screen and the applications have been exited leaving a black desktop.  Using CTRL+ALT+Backspace will kill the screen - the monitor shows a lack of signal - but then X is essentially dead.  I can resort to the (blind) CTRL+ALT+F1 and "sudo killall -HUP gdm" to get started again (there has been one occasion where this does seem to have worked, but then I can't confirm I typed correctly!).
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Sorry, as for the "whiptail" - I don't see it.  Unfortunately, I also have no reference to what "whiptail" should look like...
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ASKER

Ugh, ghesit -> gheist ! :)
So there is no GDM issue yet, it is only VESA console and X11 interaction.
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ASKER

> So there is no GDM issue yet, it is only VESA console and X11 interaction.

If you say so. ;)  By this point the user is completely blind to what is happening.  I just happen to have had an ssh connection on that one occasion to be able to diagnose what I have so far.  At what stage VESA console / X11 interaction occurs, I really don't know in the first place.
Whatever happens between X11 and framebuffer is in Xorg.0.log at time this happens (do tail -f if system hangs)
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ASKER

Hehe "do tail -f if system hangs" is a bit of a paradox. ;)  If it happens again, the Xorg.0.log survives until X is next used, correct?  If so, I have a traditional init level 3 enabled (Ubuntu by default only has X modes... hence the mention).
It may not physically flush to magnetic surface of disk but send over network some missing piece...
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ASKER

Just thought: I can copy the Xorg.0.log to another location at the time (I'll set up a script in root's directory to be sure it'll work).  When the time comes, I'll likely be typing blind.
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ASKER

Quick note: this isn't forgotten, it just hasn't recurred (yet).
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At last, hehe. ;)  Attached is the Xorg.0.log from a "blank/black" screen occurrence.
Xorg.0.log.zip
ASKER CERTIFIED SOLUTION
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gheist
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Hi gheist,

I'm not ignoring this one - I did download Mandriva's latest last week but the burn failed. :(  Will give this one another go, hopefully sooner than later.  Thanks for everything so far - much appreciated - and sorry for my delays.
knoppix has another HW detection routine just to check some.
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OK, so I've got a couple of distributions prepped for testing now... but I'm away for the next three days and that means I'll be swamped when I get back too! :(  Where does time disappear to?!

Once, again, many thanks for your patience, gheist.
No problem, just return to this question - good to know, so we do not bugger you
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ASKER

The symptoms being described seemed to be exclusive to the distribution in use.  Machine is now upgraded and symptoms are no longer present.

Much obliged to gheist for his insights and patience. :D
That was a problem while intel polished their x11 driver.
old i810 driver worked but no acceleration or widescreen.
It was change for better but at price.