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Bug 1319 - Segfault after glXChooseVisual returns null
Summary: Segfault after glXChooseVisual returns null
Status: RESOLVED DUPLICATE of bug 1333
Alias: None
Product: SDL
Classification: Unclassified
Component: video (show other bugs)
Version: HG 2.0
Hardware: x86 Linux
: P2 normal
Assignee: Sam Lantinga
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2011-10-23 03:25 UTC by Carles Pagès
Modified: 2012-01-07 20:01 UTC (History)
0 users

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Description Carles Pagès 2011-10-23 03:25:38 UTC 
If I run the gl test (testgl.c) with -fsaa option, I get a segfault in SDL_SetVideoMode. Here's the backtrace:
Program received signal SIGSEGV, Segmentation fault.
0xb7f4744c in X11_DestroyWindowFramebuffer (_this=0x804e7f8, window=0x8070048)
    at src/video/x11/SDL_x11framebuffer.c:196
196         Display *display = data->videodata->display;
(gdb) bt
#0  0xb7f4744c in X11_DestroyWindowFramebuffer (_this=0x804e7f8, window=0x8070048)
    at src/video/x11/SDL_x11framebuffer.c:196
#1  0xb7f3c77f in SDL_DestroyWindow (window=0x8070048) at src/video/SDL_video.c:1949
#2  0xb7f3a945 in SDL_CreateWindow (title=0x0, x=536805376, y=536805376, w=640, h=480, flags=6)
    at src/video/SDL_video.c:1187
#3  0xb7e7d245 in SDL_SetVideoMode (width=640, height=480, bpp=16, flags=67108864)
    at src/SDL_compat.c:538
#4  0x0804a30e in RunGLTest (argc=2, argv=0xbfffeeb4, logo=0, logocursor=0, slowly=0, bpp=16, gamma=0, 
    noframe=0, fsaa=1, sync=0, accel=-1) at testgl.c:471
#5  0x0804aeaa in main (argc=2, argv=0xbfffeeb4) at testgl.c:768

After some debugging, I see that there are two calls to X11_GL_GetVisual, in which glXChooseVisual returns null. Each time the error is ignored.

I still don't understand why the call returns null, as GLX_ARB_multisample is listed in my extensions. Any hint?
Comment 1 Sam Lantinga 2012-01-07 20:01:40 UTC 
I'm not sure why glXChooseVisual() returns NULL.  Maybe ask on the SDL mailing list?
http://www.libsdl.org/mailing-list.php

The crash when that happens though I just fixed:
http://hg.libsdl.org/SDL/rev/744ae9bdf5da

*** This bug has been marked as a duplicate of bug 1333 ***