[Bug 71924] local screen display 'lost' when remote ends XDMCP session

EricL eric.lapuyade at free.fr
Wed Nov 15 15:55:20 UTC 2006

Public bug reported:

Binary package hint: kubuntu-desktop

On machine A:

- Install Kubuntu 6.10 using the release live CD
- enable XDMCP in the corresponding section in /etc/kde3/kdm/kdmrc
- authorize access to all in /etc/kde3/kdm/Xaccess

On machine B, running Windows 2000 or XP

- run XLaunch (part of XMing) to start a new session. 
-- select options: one window, open session vis XDMCP, connect to host with IP address. Uncheck Clipboard support. Add the '-once' parameter for XMing (this shuts down XMing when the session is reset at the end).
- The login screen appears. In the 'menu' button, select "disconnect" to end the session.

when the session resets, on machine A
- look at the screen and see that it switched display to show the boot splash image (the blue Kubuntu). 
- Wait a few seconds. The splash screen disappears and all that remains is a blinking underline at the top left.
- At this point, the system is still OK. it is possible to recover the graphic screen or a terminal by using ctrl-alt F1 or F7.

Observations :

- If you try to open a new XDMCP session before you recover VT7 (that is
when it shows the blinking underline), it works one time, but machine A
will totally freeze when that new session terminates and is reset.

- If you recover VT7, I think (I don't remember for sure) you can
normally connect a new session and termnate it. Machine A will however
always 'loose' the graphic display when the remote session is

- It makes no diferrence that machie A has a local session open (KDE
desktop) or that is idle at the login screen (kdm)

- I reproduce the exact same problem on 2 totally different configurations:
-- one is an MSI P4M800/Celeron 310D/Geforce 2 (legacy proprietary OR open source driver, makes no difference) with IDE and SATA disks
-- the second is a Dell P4 3Gh with Intel integrated video and SATA disk.

- I also reproduce the problem using Cygwin/X instead of XMing.

- if you don't use the -once option to launch XMing, XMing will
automatically restart a new session when the previous one is reset. This
is OK, it shows that the system is still running normally when it
'looses' the screen.

- the only problem is when you terminate the second XDMCP session: it
totally freeze the machine.

** Affects: kubuntu-meta (Ubuntu)
     Importance: Undecided
         Status: Unconfirmed

local screen display 'lost' when remote ends XDMCP session

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