The suggestion from Marco to try a non-3D DE worked. I tried two methods: 1. minimal Centos 7 install and xfce install via CLI. Worked fine. 2. Gnome Centos 7 install and then xfce install via yum groupinstall. Worked fine.

One tip for anyone doing this:

After starting vncserver the first time, it creates a ~/.vnc/xstartup file. This will be the same type of session if you logged in locally. Edit that file so that it contains the following:

#!/bin/sh exec /bin/sh /etc/xdg/xfce4/xinitrc

Then it will start up an xfce session.

A method to debug this is to actually launch the session on the host by running the xstartup file. If it works on the host it will most likely will work on the remote client. If you try this without the xstartup file mod above it will fail with the 'oh no ...' error right there in a new window on the host. It helps avoid some running around.

Many thanks for the help on this. A nice side effect is that I am spending effort to install xfce on all my VMs. The performance improvement is dramatic. And mostly gone is that arduous Gnome3 DE. I really tried to use it. It's kind of OK for light work, but for any medium multi-tasking it is frustrating.

Stan

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Message: 25 Date: Tue, 18 Nov 2014 22:53:21 -0700 From: Stan Cruisestancruise@me.com To:centos@centos.org Subject: [CentOS] Centos 7 Nvidia openGL breaks vncserver Message-ID:546C3051.4040503@me.com Content-Type: text/plain; charset=utf-8; format=flowed

On Tue, 18 Nov 2014 10:46 pm MT -0700 Stan Cruise <stancruise at me.comhttp://lists.centos.org/mailman/listinfo/centos> wrote:

Thanks Marco.

Gnome3 it is. I naively figured that this was the 'default' but alas it is a selection which I did make.

I had seen hints of this in discussions elsewhere and did try KDE, but that is tough sledding on C7, and I got impatient. I should have stuck it out. (KDE has a bug on vncserver enable and creates the wrong symlink in /etc. At least it is different and requires work to get it right).

Mate is my next try.

I did try the nvidia-detect and it did say to use 340.58.

Thanks again for helping me converge. I will be silent for a bit to try out different DEs.

Stan

On Tue, 18 Nov 2014 11:32:36 -0700 Stan Cruise <stancruise at me.comhttp://lists.centos.org/mailman/listinfo/centos> wrote:

/ Bare metal Centos 6.5, vncserver running, client able to connect with

/>/ perfect resolution. Nvidia GT240, driver 331.49. />/ />/ Upgrade to Centos 7 with nouveau basic driver, all still works fine. />/ Resolution poor on wire connected monitor, but perfect on vnc client />/ session (1920x1080). />/ />/ Upgrade Nvidia driver via elrepo. 340.58; removed nouveau via />/ 'Software' manager. Excellent wired monitor resolution. />/ />/ But >> Client vnc connect receives the dreaded 'oh no, something />/ has .....' / Are you maybe trying to run Gnome3 through vnc by any chance? Because Gnome3 requires 3D acceleration, and I'm not sure that nvidia driver would simulate 3D stuff in software (nouveau should fall back to mesa in case hardware acceleration fails --- typical of a vnc session).

So my suggestion is to try KDE or XFCE or LXDE or Mate or... any other DE which doesn't require 3D features to work. Such DE should work through vnc using nvidia driver no problem --- the only exception is Gnome3.

/ Backed out Nvidia 340.58, back to nouveau, client vnc works again.

/>/ Also tried 304 driver (only other one in elrepo for el7) - same />/ problem. / You don't want to guess which driver you need. Use the nvidia-detect utility from elrepo, it will tell you which driver to install.

/ Research seems to indicate that openGL does not play well with vnc. I

/>/ cannot see any solutions posted as yet. />/ />/ So, what are my options? / My choice would be to try a less demanding DE first.

/ Maybe change out the video card for AMD? I cannot know if the

/>/ Catalyst driver will work, but there is a much more active and />/ extensive open driver community, which could work better than nouveau? / Catalyst driver has always been a pure gamble for me (i.e. worked 50% of time, supported 50% of video cards, and could be installed on 50% distributions... or so...). The open-source radeon driver is much better supported.

That said, the radeon community is not any more active or more extensive than the nouveau community. It's just that AMD has released the specs for their cards, so they have a much easier job of maintaining the radeon driver than the nouveau community (which basically needs to RE everything from scratch).

HTH, Marko