Illegal execution error message

[Steve Roseman]

In article <1991Apr9.134802.26440 at eagle.lerc.nasa.gov>, fsfrick at bones (David Fricker) writes:
> I'm porting a local graphics program which uses the GL calls, and I
> get the error message 'illegal execution' when it bombs.  The program
> is a scientific plotting/graphics package (3d, contours, etc.) which 
> compiles nicely (now), starts up okay, but bombs when asked to do
> graphics.
> 
> I tried running 'xde' to track down the offending call, but the following
> is all I get from the debugger:
> 
> 	Unreadable instruction at address 0x0
> 	warning: could not locate trace table from starting address 0x0
> 	Could not determine current function
> 
> As you can see, this is not very helpful.  I would appreciate any hints,
> suggestions, incantations, etc.
> 
> In case you're interested, my system is an RS/6000 model 530 running at
> level 3003.  It has the 24-bit color, Z-buffered graphics board.
> 
> 
> Thanks for any help.
> david fricker
> --
> -----------------------------------------------------------------------------
> David Fricker			|     phone: 216-433-5960
> NASA Lewis Research Center     	|     M.S. 5-11
> Cleveland, Ohio  44135         	|     email: fsfrick at bones.lerc.nasa.gov 
-- 

Funny, I had the same problem today with a non-graphics C program.  It was
working until I moved some code from the main routine to it's own procedure,
and defined some of the variables as global.  The error occurred somewhere far
off in routines that resided in a library and were not even recompiled.

I finally looked at a loadmap (-b:loadmap:filename.map switch on cc or ld), and
lo and behold, there was a redefinition of the name 'access', one of those new
global variables.  I changed the name and it worked.  There was a conflict with
something named 'access' somewhere.

This may not be your problem, but it's worth a try.  Look around for redefined
names that seem suspicious (access was only one of a hundred listed as
redefined.)

Good luck,
Steve

-------------------------------------------------------------------------
Steve Roseman
Lehigh University Computing Center
LUSGR at VAX1.CC.Lehigh.EDU