Re: xterm crashes gnome-shell

["Stefan M. Radman" <sm...@kmi.com.INVALID>]

Hi Nick,

I have not been able to reproduce the issue with another client but found two ways to resolve the issue for Guacamole:

A. Switching the Guacamole RDP session to "Color Depth: True Color (24-bit)"

B. Uncomment xserverbpp=24 in the [Xvnc] section of /etc/xrdp.ini

Either of the two avoids the crash of gnome-shell.

The default color depth of xrdp/Xvnc seems to be 32 bit.

Recently I've seen issues with widgets of cross-platform toolkits like Java Swing or Tcl/Tk not displaying or displaying incorrectly on Xvnc based GNOME desktops running under xrdp with default settings. Most of them looked like they were related to transparency.
All of them were resolved by setting the color depth of the RDP session to 24.

My Xvnc server is is part of the CentOS7 package tigervnc-server-minimal-1.8.0-17 and its man page reads

-depth depth
Specify  the pixel depth in bits of the desktop to be created.
Default is 24, other possible values are 8, 15, and 16 - anything else
is likely to cause strange behaviour by applications.

Strange and unexpected behaviour indeed.
Seems like Xvnc is not buit for 32 bit.

xserverbpp=24 is my new default.

Stefan

On Jul 28, 2018, at 17:12, Nick Couchman <vn...@apache.org>> wrote:

On Sat, Jul 7, 2018 at 6:56 PM Stefan M. Radman <sm...@kmi.com>> wrote:
Hi Nick

First, gnome-shell crashes (you notice by the desktop going black and the window decorations disappearing) but ultimately the whole xrdp/Xvnc session dies (Guacamole asks me if I want to logout or reconnect).
Sometimes it takes a little bit longer and I can still interact with window contents while the window manager is long gone but in the end it just dies on me.

There are lots of [abrt] emails and they contain stack traces.
See the last one further below. The previous ones look pretty much the same.

I've never run xrdp/Xvnc or gnome-shell under gdb or strace but if you have a hint for me on how to do this I'll give it a try.

Thanks
Stefan


Stefan,
Sorry for the delay in responding, here.  It sounds like the most likely cause is some difference between how guacd is establishing the VNC connection and the other VNC clients.  Not sure if it's a quality, encoding, etc., sort of thing, but that's my best guess.  Any chance you can try different settings for the non-Guacamole VNC client and see if you're able to reproduce it at all with that - things like color depth, encoding, quality, etc.?  Also might want to play with the settings in Guacamole that you can adjust and see if any adjustments to that resolve the issue.

-Nick



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