Bug in interaction between freeglut and mesa-7.3-rc2

Florian Echtler floe at butterbrot.org
Sat Jan 17 02:28:38 PST 2009


>> The bug causes a segfault in libGL.so, though even with debug info
>> enabled, I can't see the exact location. However, I can work around the
>> bug when, in freeglut, I replace
> Why would you do that?  There is no improvement to freeglut and no
> benefit to its users.  If the read drawable and the drawing drawable are
> always the same, just use glXMakeCurrent.  You already have a tool that
> does *exactly* the job you need done.  Why change to a tool that is
> intended to suit a different need?
Uh, I do that because I need to use freeglut with the opensource drivers 
and DRI? It won't work otherwise. Note: freeglut currently contains 
_glxMakeContextCurrent_, which I replaced by _glXMakeCurrent_, not the 
other way round.

If I remember correctly, I already posted this patch to the freeglut 
mailing list last fall, where it was rejected, citing possible side 
effects on other platforms. As I am not a regular freeglut developer, I 
accepted that and (wrongly) concluded that it has to be fixed in Mesa.

So let me summarize:
- there is a bug in Mesa which causes glxMakeContextCurrent to segfault,
- but it only occurs because freeglut doesn't call glXMakeCurrent, as it
   really should, and passes invalid parameters, too.

If that is correct, could somebody with more authority than me 
please convince the freeglut guys to fix it? As freeglut is the default GLUT 
implementation on most distros, I consider this quite important for 
acceptance of the opensource DRI drivers.. a _lot_ of software uses GLUT, 
and consequently crashes.

Yours, Florian
-- 
"_Nothing_ brightens up my morning. Coffee simply provides a shade of
grey just above the pitch-black of the infinite depths of the _abyss_."



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