Bug#1116031: nexuiz: Does not start on Vivante GC7000 GPU: GLXBadFBConfig

[Simon McVittie]

Control: retitle -1 nexuiz: Does not start on Vivante GC7000 GPU: GLXBadFBConfig
Control: reassign -1 darkplaces 0~20180908~beta1-7

nexuiz is just a script to run the darkplaces engine with the 
Nexiuz Classic game data, so I'm reassigning this to the darkplaces 
engine: any decisions being made about video modes and drivers are a 
matter for the engine rather than the game.

On Tue, 23 Sep 2025 at 13:42:51 +0200, Ælla Chiana Arson Bobbie Moskopp wrote:
>I just installed Nexuiz on my MNT Reform 2, which has a Vivante GC7000 GPU.

What graphics driver is in use on this system: Mesa, or some other 
(perhaps proprietary) driver? Presumably Mesa, since you mentioned 
MESA_GL_VERSION_OVERRIDE as a workaround?

What versions of OpenGL and OpenGL|ES does that driver implement on this 
hardware?

If your CPU is sufficiently new/fast, running with environment variable 
LIBGL_ALWAYS_SOFTWARE=1 to avoid relying on the GPU might help.

>I found that this does not happen when you start nexuiz like this:
>
>MESA_GL_VERSION_OVERRIDE=4.0 nexuiz

Since 2019 the darkplaces engine requires OpenGL ("desktop" GL) version 3.2
(or OpenGL|ES version 2.0, but that's a compile-time choice only, and we
compile it for "desktop" GL on Debian). It used to have an OpenGL 1.x 
renderer, but that was removed by the upstream developers.

I believe the meaning of MESA_GL_VERSION_OVERRIDE=4.0 is that it 
instructs Mesa to lie to the game/client, and pretend that it implements 
OpenGL 4.0, even though it doesn't really. That could work as a 
workaround (at your own risk), or it could briefly work and then crash 
later because your Mesa version doesn't implement a feature that the 
game requires.

>In case it matters: I am using sway(1) as wayland compositor.

Are you running the game as a native Wayland client, or via X11 and 
Xwayland? By default, SDL 2 uses X11 via Xwayland, unless you have taken 
steps to force it to use the native Wayland protocol (because its 
ability to do "normal game things" on the native Wayland protocol is 
known to be incomplete).

It would be interesting to know whether

     SDL_VIDEODRIVER=wayland nexuiz

has a different result.

It would also be interesting to know whether installing the libsdl2-compat 
package, and running

     SDL2COMPAT_DEBUG_LOGGING=1 \
     SDL_DYNAMIC_API='/usr/$LIB/sdl2-compat/libSDL2-2.0.so.0' \
     nexuiz

has a different result. (This version of SDL is likely to become the 
default for SDL2 games before the Debian 14 release, and it *does* 
default to native Wayland under some circumstances: for now, consider it 
to be a preview.)

     smcv