Static linking and dynamic OpenGL

SDL Development
1

I’m not sure if this is SDL related, so if it isn’t can someone please
direct me to the proper people.

I’m having a problem with static linking a binary and dynamically
loading OpenGL (using SDL_GL_LoadLibrary). When doing non-static
linking, dynamically loading the GL lib works fine. This has been
tested in Linux/OSX/Win32. But when I statically link the app in
Linux, switching to OpenGL mode just causes a segfault. It may not
have to do with the static linking at all, but that’s the only time I
see it.

FYI, this is a GPL application (Stella, Atari 2600 emulator), so it’s
freely available, and I’m not trying to bypass the GPL by doing a
static build. I’m just trying to set up nightly builds that are
independent of distro.

Anyone heard of this before?

Thanks,
Steve

2

I’m not sure if this is SDL related, so if it isn’t can someone please
direct me to the proper people.

I’m having a problem with static linking a binary and dynamically
loading OpenGL (using SDL_GL_LoadLibrary). When doing non-static
linking, dynamically loading the GL lib works fine. This has been
tested in Linux/OSX/Win32. But when I statically link the app in
Linux, switching to OpenGL mode just causes a segfault. It may not
have to do with the static linking at all, but that’s the only time I
see it.

I don’t think you can statically link an application and dynamically load GL
under Linux. Ryan, have you ever done this?

-Sam Lantinga, Senior Software Engineer, Blizzard Entertainment
3

I don’t think you can statically link an application and dynamically load GL
under Linux. Ryan, have you ever done this?

Statically linking what? OpenGL, SDL, both? Are you using the -static
command line?

–ryan.

4

Maybe I’m confusing the terms. Here’s a clearer breakdown:

Case 1) App is statically linked, but isn’t linked to OpenGL at all.
Doing ‘ldd’ results in ‘static executable’. When using
SDL_GL_LoadLibrary(), it causes a segfault.

Case 2) App is using shared libs, and still isn’t linked to OpenGL.
Doing ‘ldd’ lists all the libs linked to the app. Using
SDL_GL_LoadLibrary() in this case works fine.

So, overall:

  1. OpenGL is never linked to the app at all, and is loaded through
    SDL_GL_LoadLibrary().

  2. Both cases work fine in OSX and Win32. So it seems the problem only
    occurs when a static Linux binary attempts to dynamically load OpenGL
    through SDL_GL_LoadLibrary().

  3. The point of this whole exercise is to get around the brokenness of
    Linux wrt creating an app that will work everywhere. Notice that OSX
    and Win32 don’t have a problem with that.

SteveOn January 19, 2006 06:21 am, Ryan C. Gordon wrote:

I don’t think you can statically link an application and
dynamically load GL under Linux. Ryan, have you ever done this?

Statically linking what? OpenGL, SDL, both? Are you using the -static
command line?

5
  1. The point of this whole exercise is to get around the brokenness of
    Linux wrt creating an app that will work everywhere. Notice that OSX
    and Win32 don’t have a problem with that.

I dynamically link libc, pthread, X11 and OpenGL, and statically link
everything else. I’ve never had a problem with that. My magic LIBS line is:

LIBS = -L/usr/X11R6/lib -L/usr/local/lib -Wl,-rpath,/usr/local/lib,-Bstatic
-lSDL_sound -lSDL -lsmpeg -lmikmod -lvorbisfile -lvorbis -logg -lXxf86dga
-lXxf86vm -lXv -lXinerama -lXi -lpng -lz -lstdc++ -Wl,-Bdynamic -lpthread
-lGL -lX11 -lXext -ldl

  • Andreas
6

Thanks for that, I’ll try it out.

SteveOn January 20, 2006 06:33 am, Andreas Umbach wrote:

  1. The point of this whole exercise is to get around the
    brokenness of Linux wrt creating an app that will work everywhere.
    Notice that OSX and Win32 don’t have a problem with that.

I dynamically link libc, pthread, X11 and OpenGL, and statically link
everything else. I’ve never had a problem with that. My magic LIBS
line is:

LIBS = -L/usr/X11R6/lib -L/usr/local/lib
-Wl,-rpath,/usr/local/lib,-Bstatic -lSDL_sound -lSDL -lsmpeg -lmikmod
-lvorbisfile -lvorbis -logg -lXxf86dga -lXxf86vm -lXv -lXinerama -lXi
-lpng -lz -lstdc++ -Wl,-Bdynamic -lpthread -lGL -lX11 -lXext -ldl