I am trying to get xinerama to work with x11vnc on Xvfb and I am getting:
xdpyinfo -ext XINERAMA

Xlib: extension "XINERAMA" missing on display ":0.0".
XINERAMA extension not supported by server

I am using the latest version of x11vnc which says XINERAMA is on by default. I have tried xf4vnc as well and get the same issue.

Xvfb :1 -screen 0 1024x2048x24 &
mwm &
x11vnc -display :1 -bg -nopw -xkb -N

I get a screen that looks like xinerama and windows pass from display to display fine, however xdpyinfo says otherwise and we have software that looks to xdpyinfo to get information about how display guis.

When x11vnc was compiled it said it found libXinerama. Not sure what is going on. Does vncviewer need to support xinerama as well? Is there any way to tell if vncviewer does without downloading a newer or different version?

I don't believe the virtual frame buffer (i.e. RAM only) X server 'Xvfb' supports the XINERAMA X extension.

It doesn't matter if x11vnc was built with the libXinerama client library, if the X server (Xvfb in this case) doesn't support XINERAMA there is nothing x11vnc can do about it. x11vnc is not an X11 server it is an X11 client.

I'm not sure what you are trying to do. XINERAMA makes multiple physical monitors look like one big screen. Why do that with Xvfb?

x11vnc doesn't do very much via libXinerama, it only uses it to check if the big screen is non-rectangular (e.g. one big monitor and one small monitor) so it can fill in the "empty" part of the screen with black. That's the end of what it does with XINERAMA.

If you want to split up a big screen into pieces that get viewed on multiple monitors you will need to run multiple x11vnc processes and multiple vncviewers:

http://www.karlrunge.com/x11vnc/faq.html#faq-xinerama

http://www.karlrunge.com/x11vnc/faq....q-multi-screen

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The X/VNC server is a single head system and the VNC clients are dual heads. I can make the VNC client screens look and feel like XINERAMA with x11vnc, however we have been given software that looks to "xdpyinfo -ext XINERAMA" to tell it where to position certain GUIs and can not change that.
Thanks for taking your time to answer. But from what it sounds like you are saying no matter I how might try, running x11vnc will never show the xdpyinfo I am trying to see.

I was using Xvfb because the server does not need X on it. And you are right Xvfb does not support XINERAMA.

Out next try is to insert a dual head card in the server, run X as dual head with Xinerama and then try x11vnc again.

Actually I checked and Xvfb does support XINERAMA, e.g.:

This was done on debian squeeze/testing (sorry I don't know the Xorg version for it; I can check if you cannot figure it out.)

This gives you the 'xdpyinfo -ext XINERAMA':

XINERAMA version 1.1 opcode: 129
head #0: 1024x768 @ 0,0
head #1: 1024x768 @ 0,0

However the problem is the two subscreens are on top of eachother. I don't know how to shift head#1 over. Maybe it can be done...

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It must be that the RedHat 5 version of X we are using does not support Xinerama with Xvfb because we have tried that exact command with out luck.
Xvfb :1 +xinerama -screen 0 1024x768x24 -screen 1 1024x768x24

We want them stacked so that is great. The fact that you were successful means that we should install a custom version of X on RedHat. Thank you for effort.