Bug 70706 - QT applications crash in "Render-less" XDMCP servers
QT applications crash in "Render-less" XDMCP servers
Product: Red Hat Linux
Classification: Retired
Component: qt (Show other bugs)
i386 Linux
medium Severity high
: ---
: ---
Assigned To: Thomas Woerner
Mike McLean
Depends On:
Blocks: 67218 79579
  Show dependency treegraph
Reported: 2002-08-04 08:06 EDT by Peter van Egdom
Modified: 2007-04-18 12:45 EDT (History)
1 user (show)

See Also:
Fixed In Version: qt-3.1.1-6
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2003-05-01 18:01:36 EDT
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:

Attachments (Terms of Use)
gdm shows itself to Reflection X (63.58 KB, image/png)
2002-08-04 08:07 EDT, Peter van Egdom
no flags Details
Gnome error just after starting Gnome from gdm (422.14 KB, image/png)
2002-08-04 08:09 EDT, Peter van Egdom
no flags Details
KDE crash just after starting KDE from gdm (49.97 KB, image/png)
2002-08-04 08:11 EDT, Peter van Egdom
no flags Details
At this time everything seems OK (46.36 KB, image/png)
2002-08-05 18:32 EDT, Peter van Egdom
no flags Details
.. but after clicking on the "K" this happens (27.34 KB, image/png)
2002-08-05 18:34 EDT, Peter van Egdom
no flags Details
Eventually also the icons disappear (13.52 KB, image/png)
2002-08-05 18:35 EDT, Peter van Egdom
no flags Details

  None (edit)
Description Peter van Egdom 2002-08-04 08:06:05 EDT
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.1b) Gecko/20020721

Description of problem:
First of all, I wasn't really sure if I had to file this bug against KDE,
XFree86 or gdm. I chose gdm because of the XDMCP issues involved.

I have a machine running Red Hat Linux 7.3.93 (Limbo 2) which - aside from
most of the bugs reported in Bugzilla - is running fine (locally / me sitting
on the chair behind that Linux PC).

I also have a PC running Microsoft Windows with Reflection X.

On the PC running Limbo beta 2, I configured gdm to listen to X connections.

On the PC running Windows & Reflection X I do a XDMCP connection with a XDMCP
Broadcast. This works fine, and gdm presents itself to me on Windows on my
Reflection X Root Window.

When I select "Gnome" from 'Session' at the bottom of the screen and log in
with my username & password, Gnome starts up (although it gives an error
concerning /dev/sound/mixer. Apart from this error of the sound daemon
Gnome seems to work ok.

OK, _but_ when I select "KDE" from 'session' at the bottom of the screen and
log in with my username / password, KDE starts up but crashes at a certain
point with a message about /dev/dsp (error goes offscreen really fast) and
gives a unreadable 'artsmessage' pop-up.

I made some screenshots where you can show for yourself. :-)

At first I thought it was a soundcard module issue, because when I start KDE
from gdm _locally_ the following modules are automatically loaded by KDE :

   - i810_audio             24712   1  (autoclean)
   - ac97_codec             13320   0  (autoclean) [i810_audio]
   - soundcore               6500   2  (autoclean) [i810_audio]

Then I rebooted the Linux box and tried starting KDE from gdm remotely with
XDMCP by using Reflection X on Windows. This time KDE did not automatically
loaded the necessary soundcard modules.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. Setup gdm so it listens to XDMCP connections.
2. Use Reflection X on a Windows PC to connect to the Linux box.

Actual Results:
Gnome is able to start - but with a warning / error about "/dev/sound/mixer".
Gnome seems fine apart from this error.

KDE crashes after trying to start - with a error about "/dev/dsp" (..I think,
the error disapppears quite fast). KDE does not repond to mouse clicks and the
X Client on the Windows PC has to be restarted.

Expected Results:
Both Gnome and KDE should work fine just as if they were started locally /
me sitting on a chair (behind / in front of) the Linux box.

Additional info:

[root@limbo-pc root]# rpm -qa |grep -i xfre
[root@limbo-pc root]# rpm -qa |grep -i gdm
[root@limbo-pc root]# rpm -qa |grep -i kdeba
Comment 1 Peter van Egdom 2002-08-04 08:07:46 EDT
Created attachment 68807 [details]
gdm shows itself to Reflection X
Comment 2 Peter van Egdom 2002-08-04 08:09:35 EDT
Created attachment 68808 [details]
Gnome error just after starting Gnome from gdm
Comment 3 Peter van Egdom 2002-08-04 08:11:16 EDT
Created attachment 68809 [details]
KDE crash just after starting KDE from gdm
Comment 4 Havoc Pennington 2002-08-04 11:54:37 EDT
I would initially guess that this is a KDE issue. Thanks for the detailed report.
Comment 5 Warren Togami 2002-08-05 08:32:05 EDT
I have seen several KDE startup crashes in Limbo due to sound device related
errors, even when running KDE on a standalone machine.  If you agree that this
is possibly a KDE sound issue, please rename the short summary in order to more
easily identify this bug.
Comment 6 Peter van Egdom 2002-08-05 14:18:14 EDT
Hmm. I thought about this for a while.

Warren : You're right... KDE relies on the presence of the soundcard modules too

I'll rename the short summary of this bug entry to something more appropriate.

Comment 7 Warren Togami 2002-08-05 15:14:52 EDT
I may also be wrong in this diagnosis, but this is what I suspected after seeing
KDE crash on machines like nForce without sound drivers properly configured.

I would also recommend high priority, high severity because this is a killer
showstopper for LTSP.
Comment 8 Peter van Egdom 2002-08-05 18:30:23 EDT
This evening I tried to find out some more of this bug.

I think there are at least two major kind of issues with KDE in Limbo beta 2.

 - Sound dependency (no soundcard / driver --> no KDE).
 - XDMCP issues (strange crashes).

(I really hope XDMCP eventually works as it should, because it is ideal to let
 people play with Linux in a company where X clients are used).


This evening I loaded KDE locally on the machine, which caused the necessary
sound modules to be 'modprobed' automatically by artsd. 
I then exited KDE locally so I saw gdm again.

(I went to CTRL-ALT-F1 to make sure the sound-modules were still loaded).

So I went to my Windows machine with Reflection X and tried starting KDE from
gdm. After a few seconds KDE's icons began to show on screen - this time without
an error from arts about "/dev/dsp" missing - and I really thought that this
time it worked ('it' being a workable KDE session with XDMCP).

But, alas, as soon as I clicked on the "K" button on the bottom left of the
screen, the KDE Kicker crashed, showing only the KDE icons on the desktop.
After maybe 10 seconds, also the icons disappeared leaving me alone with an
empty KDE desktop.

I made some screenshots to illustrate what I just said.

(I do not experience this kind of behaviour of KDE when using the machine

Perhaps it would be wise to make some separate bugreports of this issue.

Is there anyone who can reproduce this problem by using Reflection X - or
another X client - for Windows?

(I haven't tried "Linux box X" XDMCP to "Linux box Y" XDMCP, though).

Comment 9 Peter van Egdom 2002-08-05 18:32:49 EDT
Created attachment 69005 [details]
At this time everything seems OK
Comment 10 Peter van Egdom 2002-08-05 18:34:02 EDT
Created attachment 69006 [details]
.. but after clicking on the "K" this happens
Comment 11 Peter van Egdom 2002-08-05 18:35:03 EDT
Created attachment 69007 [details]
Eventually also the icons disappear
Comment 12 Bernhard Rosenkraenzer 2002-08-06 07:08:52 EDT
I can't reproduce this with Linux -> Linux (I do get the message, but it's 
readable (you don't have permissions to access /dev/dsp), and goes away when I 
click it), so this looks like a bug in Reflection. 
Can you reproduce this with anything else? 
Comment 13 Warren Togami 2002-08-06 07:39:00 EDT
I must apologize, I somehow mistook a system crash (unrelated sound driver bugs,
triggered during KDE startup) for a KDE crash.  This bug may be entirely XDMCP
related.  I will continue to test both XDMCP and sound tomorrow.

Bero, out of curiosity does it still work properly with XRENDER disabled on the
X -query side?
Comment 14 Peter van Egdom 2002-08-06 14:56:49 EDT
Played, re-thought and experimented a bit more...

I was trying to reproduce a LICQ bug and by coincidence I started LICQ
from the command-line in a Gnome session (started from GDM in Reflection X).

After typing in "licq", the following output appeared :

20:07:56: [WRN] Licq: Ignoring stale lockfile (pid 8082)

Xlib:  extension "RENDER" missing on display "".
Xlib:  extension "RENDER" missing on display "".
Licq Segmentation Violation Detected.
/lib/i686/libpthread.so.0 [0x40133267]
Attempting to generate core file.

So, it also seems LICQ needs the RENDER extension.

Probably all QT stuff requires the RENDER extension.
If a 'RENDER complient' X server cannot be found, the application crashes.

My guess that the same is happening in KDE starting from gdm in a
Reflection X session.

(see screenshot)

But because that session didn't give any useful output, I never thought
of the RENDER extension.

Bero, can you do a Linux XDMCP <-> Linux XDMCP test using e.g. 
Red Hat Linux 6.2 to connect to Red Hat Linux 7.3.93?

I think Red Hat Linux 6.2 doesn't have a RENDER extension in the X server.
So also that probably will trigger the bug.

I'll rename the short summary to something more appropriate.

A lot of X servers don't have the 'RENDER extension'.
Main question is... Are these people ruled out of using KDE 3.02 
remotely with Red Hat 7.3.93?

Comment 15 Peter van Egdom 2002-08-22 17:24:19 EDT
Problem still exists in Red Hat Linux 7.3.94 ('null').
Comment 16 Peter van Egdom 2003-05-01 18:01:36 EDT
It seems that Red Hat Linux release 9 (Shrike) contains changes that fixes this
problem for me. Those changes probably are in the QT library; I've successfully
started both Licq from a XDMCP Gnome session via Reflection for Windows and KDE
itself from a XDMP session via Reflection.

- Changing component from "kdebase" to "qt".
- I'll close this bug with resolution "CURRENTRELEASE".
  (probably fixed somewhere in the upstream package).

Note You need to log in before you can comment on or make changes to this bug.