[winswitch] How to use the Xdummy with Xpra?

Heng Zhou hzhou1 at cs.uml.edu
Sat Dec 27 16:53:10 GMT 2014

Thanks for the reply. I don't understand "if you have access to a real
graphics card in the server system". By "server system" here do you mean
the remote machine? I asked the question in the original post just because
the remote machine is not installed a physical graphics card, so I tried to
use Xdummy (or Xvfb) to setup a virtual graphics card (or virtual frame
buffer). So the settings of my question is that there is no physical
graphics card on the remote machine, and I tried to run glxgears on it and
return the animation back to me. You said your forwarding of glxgears works
fine. Is it working on a remote machine without  physical graphics card? If
so, could you please share your settings and running steps? To be specific,
is the remote machine running Red Hat? Is the following commands the
sequence of steps you did:
(1) xpra start :100
(2) sudo DISPLAY=:100 Xorg -noreset +extension GLX :200
My remote ubuntu machine dies at this step.
(3) Use Xpra Launcher in Windows to connect to the remote machine using
display :200
(4) sudo DISPLAY=:200 glxgears
Then the Xpra window in WIndows should display the animation of rolling
gears, right?

On Sat, Dec 27, 2014 at 11:16 AM, Antoine Martin <antoine at nagafix.co.uk>

> On 27/12/14 22:45, Heng Zhou wrote:
> > Hi,
> >
> > According to The webpage https://www.xpra.org/trac/wiki/Xdummy and
> > http://en.wikipedia.org/wiki/Xvfb, my understanding is that, using
> "Xdummy
> > with Xpra", we can run any program that produce graphical output on a
> > computer that does not install any physical graphics card and physical
> > screen, because the output of the program can be produced by Xdummy and
> > transfered to my local computer through Xpra. It is true for OpenGL
> program
> > in particular, assuming I have installed mesa in which a software
> > simulation of OpenGL rasterization is implemented. Am I right? If I am,
> how
> > can we run an OpenGL program, say, glxinfo or glmark2, on a remote
> machine
> > that has no physical graphics card (so /dev/dri/card0 and /dev/fb0 do not
> > exist as a result), e.g., the Amazon EC2 t2.micro instance running ubuntu
> > 14.04, and transfer the output (the animation) back to my local
> computer? I
> > can not grasp the idea of the example in the aforementioned Xdummy
> webpage,
> > and searching the internet (for a couple of days already) did not gives
> me
> > any useful hint. So could you please help me with this question? Thank
> you
> > very much.
> The default xpra installations using Xdummy support OpenGL as the Xorg
> command line includes "+extension GLX".
> Forwarding "glxgears" (or any other gl application) works fine out of
> the box, if you have access to a real graphics card in the server system
> you can also use VirtualGL to get hardware acceleration.
> Unfortunately, Ubuntu does weird things with their Xorg server
> installation and so you may not be able to use Xdummy on Ubuntu.
> Cheers
> Antoine
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