How to avoid this Xvfb error: ES2 Prism: Error - GLX extension is not supported

[Adam Jackson]

On Fri, 2016-12-09 at 14:09 -0500, Long Vu wrote:
> Hi,
> 
> We use Xvfb to avoid having to run an X server on our build machine.
> 
> We got this error with Xvfb that we do not have when we were running a
> real VNC server just to provide X.
> 
> ES2 Prism: Error - GLX extension is not supported
>    GLX version 1.3 or higher is required
> Xlib:  extension "RANDR" missing on display ":99".
> 
> Is there something we can do to avoid this error?

How are you launching Xvfb? I believe it defaults to 8bpp, but GLX only
works at 16 or 32bpp.

- ajax