[Mesa-dev] VTK Offscreen Segfaults

[Kevin H. Hobbs]

On 08/06/2010 05:20 PM, tom fogal wrote:
> Well, it does appear to be some type of symbol resolution/overloading
> issue.  However it seems to be with internal Mesa symbols.  Switching
> to a single library -- that is, putting OSMesaCreateContext, etc. into
> libGL directly, and getting rid of libOSMesa altogether -- seems like
> it would be the solution, but I imagine there's some reason that's not
> happening already.
> 
> Let's ping Dan (added to the CC list), he knows more about this kind
> of thing than I do.  Dan, have you been following this thread?  The
> working theory is that there is a symbol in both libOSMesa and libGL.
> Something about the symbol existing in both is causing Badness during
> linking; seemingly innocuous changes cause Kevin's test program to
> jump into odd parts of Mesa (e.g. VBO code while doing initial matrix
> setup).  The issue appears to be with internal symbols, but hidden
> symbol visibility isn't helping.

I just did what might be an interesting experiment.

I built mesa from HEAD with :

./autogen.sh --with-driver=xlib --disable-gallium --without-demos
--enable-debug

I set

VTK_USE_X:BOOL=OFF
OPENGL_gl_LIBRARY:FILEPATH=/home/kevin/mesa/lib/libGL.so
OSMESA_LIBRARY:FILEPATH=/home/kevin/mesa/lib/libOSMesa.so

in cmake and I still get the segfault but now I don't NEED libGL.so so
when I replace libGL.so with libOSMesa.so :

VTK_USE_X:BOOL=OFF
OPENGL_gl_LIBRARY:FILEPATH=/home/kevin/mesa/lib/libOSMesa.so
OSMESA_LIBRARY:FILEPATH=/home/kevin/mesa/lib/libOSMesa.so

There is no more segfault and the test passes.

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