Tracing ELF shared libs.
Sat May 9 15:40:00 GMT 1998

Hi all,

I realise that this list is mainly concerned with the development of
gdb (good to see things moving forward again), but I've got a query
about gdb and it's (possible) limitations. I was hoping somebody here
could help me out. I've read through the GDB info files and done
various web searches, but to no avail. I expect this is something
specific to ELF shared libs.

Humour Me :)

I'm currently trying to develop some additions to various shared
libraries on a Linux ELF system (Kernel 2.0.33, GCC 2.7.2, GDB 4.16,
libc 5.3.12 & binutils 2.7.0), and I'm using GDB to trace through the
calls to the shared libs.

Now, I can step into the shared library if I've hit a breakpoint in
the application code, but if I hit a breakpoint in the shared lib gdb
will not step into any functions.

So, do I need to upgrade to 4.17? Is system missing something it
needs to do shared lib debug? or is this just a limitation?

Below is a session grab. [] denotes my comments. I'm afraid it's a
little over complex, but I believe it shows the problem reasonably

Thanks in advance

-- -- Home     -- Work

[3d@stimpy ~/Mesa-3.0]$ gdb demos/multitex
GDB is free software and you are welcome to distribute copies of it
 under certain conditions; type "show copying" to see the conditions.
There is absolutely no warranty for GDB; type "show warranty" for details.
GDB 4.16 (i586-unknown-linux), Copyright 1996 Free Software Foundation, Inc...
(gdb) break main
Breakpoint 1 at 0x804b8b0: file multitex.c, line 275.
(gdb) r
Starting program: /home/3d/Mesa-3.0/demos/multitex 
warning: Unable to find dynamic linker breakpoint function.
warning: GDB will be unable to debug shared library initializers
warning: and track explicitly loaded dynamic code.
[What does this mean?]

Breakpoint 1, main (argc=1, argv=0xbffffcc4) at multitex.c:275
275	   glutInit( &argc, argv );
(gdb) break __glutSetWindow
[Set breakpoint in the shared lib]
Breakpoint 2 at 0x40026300: file glut_win.c, line 140.
(gdb) cont

Breakpoint 2, __glutSetWindow (window=0x804df70) at glut_win.c:140
140	  __glutCurrentWindow = window;
(gdb) list
135	     assumption breaks when GLUT is expected to integrated with
136	     other OpenGL windowing APIs that also make current to
137	     OpenGL contexts.  Since glXMakeCurrent short-circuits the
138	     "already bound" case, GLUT avoids the temptation to do so
139	     too. */
140	  __glutCurrentWindow = window;
142	  glXMakeCurrent(__glutDisplay, __glutCurrentWindow->renderWin,
143	    __glutCurrentWindow->renderCtx);
[OK, I'm here. The breakpoint has worked]
(gdb) s
142	  glXMakeCurrent(__glutDisplay, __glutCurrentWindow->renderWin,
[This is a function call to another shared lib. Stepped over]
152	  if (!__glutCurrentWindow->isDirect)
160	  if (__glutDebug)
[This is a function call in the same shared lib. Stepped over]
162	}

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