Red Hat Bugzilla – Bug 162304
VNC module on FC4 / gnome corrupts display
Last modified: 2013-04-30 19:33:14 EDT
Description of problem:
I load vnc as a module via xorg.conf .. When I login remote now, the display
gets corrupted with each application screen message or movement of cursor etc.
For eg, if on scrolling a list box, messages are displayed within the dialog,
these messages are displayed on the screen now (one on top of the other) and the
display gets corrupted.
Version-Release number of selected component (if applicable):
Start vnc.so via xorg.conf and login from the vnc client
Steps to Reproduce:
1. Install vnc.so via xorg.conf
2. Login from vnc client
3. Start using the remote display and screen gets corrupted
Clear display, no corruption
Always reproducbile. Did not occur in FC2 or FC3. My install is an upgrade
from FC3 (P4 HT 2.8, 512MB RAM, ASUS motherboard, onboard graphics) Remote
machine is a windowsxp laptop
Please show me a screen shot of the VNC viewer window, so that I can see what
sort of corruption is happening.
Created attachment 116520 [details]
Screenshots of the corrupted screen as requested
Apologies for the delay. As requested I have attached 3 screenshots of the
corrupted screen as displayed on the windows xp vnc viewer
What does 'rpm -q vnc-server' say?
Hmm, wonder if this is related to RENDER.
Please try with these packages:
I have disabled the RENDER support. Does that make the problem go away?
Yes the problem goes away with the vnc-server-4.1.1-10.0.0.1 that I downloaded
from the ftp path above.
Looks like this fixes it :-)
The real fix would be to make RENDER support work. However, I have spent some
time on this and discovered that OpenOffice.org can cause
Xvnc-with-RENDER-support to get into some sort of busy loop.
This RENDER stuff has taken too much time now, so I'm going to pull it out. :-(
I had seen this problem also, and just wondered if you installed just the
vnc-server alone or this plus vnc ? I presume that only installing the server
rpm did the trick ?
I guess that the client machine did not need changing?
Did you simply run the rpm in using rpm -ivh .....rpm or did you do more than this ?
No Change on client
Server - rpm -Uvh
OK Thanks Srini
I wonder if this is going to be fixed upstream soon? and if so how soon it will
be in the normal updates (or test updates soon first)? Perhaps Tim might be able
to give us an idea of timescale for the fix to appear in the update rpms.
I have now run some tests with the versions of the replacment RPMs quoted in
comment #6 above. In this case both the server and the client machine are
running FC4 fully up to date. The server is running Gnome and the client KDE.
test 1) installed the vnc-server version vnc-server-4.1.1-10.0.0.1 on the server
Tried to vnc in from the client running the stock version of vnc - it still had
the same screen corruption problems that were there before.
test 2) I now installed vnc-4.1.1-10.0.0.1 on the client machine and tried again.
Still the same.
test 3) had the modified version of both vnc and vnc-server on both server and
Still not working and still the same screen corruption problem.
(As a matter of interest the same client running FC4 with the stock version of
vnc is able to vnc in to a different machine runing fc3 with up to date fc3
versions of vnc and vnc-server, and this presents no problems with screen
painting or any kind of corruption)
I have reverted to the stock versions of vnc and vnc-server on both machines and
now cannot use vnc on these machines until this problem is rectified.
Since this is a part of the system which I rely on I believe this needs to be
fixed quite urgently.
The new versions of the vnc and vnc-server DO indeed fix the problem - I think
that when I did the original checks I may not have re-started X after installing
the RPMs - I have done a new test installing both vnc and vnc-server (version
4.1.1-10.0.0.1) on both server and client and then re-started X on both machines.
Now vnc works perfectly without screen corruption at all.
So thanks Tim for the update rpms - I should have been more careful about
checking that I had re-started X before running vnc after the changes.
Great - everything golden again!
Created attachment 117823 [details]
Improved vncHooks.cc:vncHooksComposite that might solve this problem
We'll look at RENDER again for FC6.
(In reply to comment #14)
> Created an attachment (id=117823) 
> Improved vncHooks.cc:vncHooksComposite that might solve this problem
Hmm, interesting solution. Please, could you tell me how can be your code
imported to vncHooks.cc?? (which class you want substitute...)
If I remember correctly, there's no vncHooks.cc:vncHooksComposite until you have
applied the RENDER patch. So, nothing should be substituted, but rather added.
You might want to take a look at
to see how the code is integrated into vncHooks.cc.
I can confirm that this code is stable, at least in TightVNC: We are shipping it
in ThinLinc and we haven't had any RENDER problems in a long time.
definitely imported vncHooksComposite to vncserver code. Version 4.1.2-6.fc7 is