Re: [Mesa3d-dev] Segmentation Fault in shade_rastpos

[Allen B. <ba...@lo...>]

Brian Paul wrote:
> 
> Allen Barnett wrote:
> >
> > Hi,
> >
> > I'm getting a segmentation fault in the Mesa function shade_rastpos()
> > when lighting is turned on and if no other drawing precedes a call to
> > RasterPos2i(). Attached is a sample program which demonstrates the
> > problem. I'm using Mesa 3.5.1 on RedHat 7.1/i386.
> 
> Hmmm, your test program runs fine here.  Can you get a stack trace
> with your debugger?

Sorry, I pressed the send button before I reverted the attached code to
its failure mode in my original message. Did you test it with the quad
drawing commented out as below?

> void display ( void )
> {
> #if 0
>  glBegin( GL_QUADS );
>  glVertex2i( 0, 0 );
>  glVertex2i( 50, 0 );
>  glVertex2i( 50, 50 );
>  glVertex2i( 0, 50 );
>  glEnd();
> #endif
> 
>  glRasterPos2i( 0, 0 );
> }

The output from the debugger is below.

And another question(s): How do you debug Mesa with GDB? I guess I don't
understand how to get it to compile without optimization (a ./configure
option?) and if I have to build and link with a static archive library
instead of a shared object? Any tips would be helpful.

Thanks,
Allen

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This GDB was configured as "i386-redhat-linux"...
(gdb) r
Starting program: /home/allen/lignumCAD/OGLFT/try7
[New Thread 1024 (LWP 25135)]
 
Program received signal SIGFPE, Arithmetic exception.
[Switching to Thread 1024 (LWP 25135)]
0x4023916b in _mesa_test_os_sse_exception_support ()
   from /usr/local/lib/libGL.so.1
(gdb) c
Continuing.
Brian Paul Mesa X11 1.2 Mesa 3.5
 
Program received signal SIGSEGV, Segmentation fault.
0x40119526 in shade_rastpos (ctx=0xbffff928, vertex=0x403b3177,
normal=0x1,
    Rcolor=0xbffff954, Rspec=0xbffff95c, Rindex=0x804869e) at
rastpos.c:228
228                 GET_SHINE_TAB_ENTRY( ctx->_ShineTable[0], n_dot_h,
spec_coef );
(gdb) where
#0  0x40119526 in shade_rastpos (ctx=0xbffff928, vertex=0x403b3177,
    normal=0x1, Rcolor=0xbffff954, Rspec=0xbffff95c, Rindex=0x804869e)
    at rastpos.c:228
#1  0x00000007 in ?? ()
#2  0x4002b763 in processWindowWorkList (window=0xbfffff27)
    at glut_event.c:1297
#3  0x403b3177 in __libc_start_main (main=0x8048998 <main>, argc=1,
    ubp_av=0xbffff954, init=0x8048688 <_init>, fini=0x8048ab0 <_fini>,
    rtld_fini=0x4000e184 <_dl_fini>, stack_end=0xbffff94c)
    at ../sysdeps/generic/libc-start.c:129
(gdb) l
223                    n_dot_h *= n_dot_h;
224                    n_dot_h /= LEN_SQUARED_3FV( h );
225                    shininess *= .5;
226                 }
227
228                 GET_SHINE_TAB_ENTRY( ctx->_ShineTable[0], n_dot_h,
spec_coef );
229
230                 if (spec_coef > 1.0e-10) {
231                    if
(ctx->Light.Model.ColorControl==GL_SEPARATE_SPECULAR_COLOR) {
232                       ACC_SCALE_SCALAR_3V( specularContrib,
spec_coef,