[CentOS] Centos 7 Nvidia openGL breaks vncserver

Tue Nov 18 23:02:00 UTC 2014
Marko Vojinovic <vvmarko at gmail.com>

On Tue, 18 Nov 2014 11:32:36 -0700
Stan Cruise <stancruise at me.com> 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