How to step into openGL APIs by using gdb?

Question

Here goes what I did.

Download MESA and build with --enable-debug configuration.
The build results are all in ${MESA_SRC}/lib directory.
I set the LIBGL_DRIVERS_PATH and LD_LIBRARY_PATH to the ${MESA_SRC}/lib directory to use the built results rather than the original library in my local PC. I checked that OpenGL apps are using the libraries in ${MESA_SRC}/lib by using ldd as follows:

~/work/mesa$ ldd /usr/bin/glxgears  | grep libGL
    libGL.so.1 => lib/libGL.so.1 (0x00007f81aa9cc000)

where lib/libGL.so.1 is the build results from mesa source code.

Now, I wrote a very simple OpenGL app. Let say A. And run gdb and breakpoint to main.

work/mesa$  gdb A
GNU gdb (Ubuntu 7.7-0ubuntu3.1) 7.7
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
(gdb) b main
Breakpoint 1 at 0x4015af: file A.c, line 168.
(gdb) r
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Breakpoint 1, main (argc=1, argv=0x7fffffffdee8) at compositor-pbo.c:168
168 {
(gdb)

After that, I tried to load solib-search-path

(gdb) set solib-search-path /home/jyyoo/work/mesa/lib

where /home/jyyoo/work/mesa is the ${MESA_SRC}. But, I don't see any so files loading. As far as I know, if I issue solib-search-path, the loading of so files in the corresponding directory should be listed with. But, I don't see any. I know that there is a list of so files as follows:

$ ls /home/jyyoo/work/mesa/lib/*.so
/home/jyyoo/work/mesa/lib/i965_dri.so  
/home/jyyoo/work/mesa/lib/libglapi.so
/home/jyyoo/work/mesa/lib/libGL.so
/home/jyyoo/work/mesa/lib/libEGL.so
/home/jyyoo/work/mesa/lib/libGLESv1_CM.so
/home/jyyoo/work/mesa/lib/mesa_dri_drivers.so
/home/jyyoo/work/mesa/lib/libgbm.so
/home/jyyoo/work/mesa/lib/libGLESv2.so

So, if I try to 's' in gl functions, it does not step into...

Additionally, if I see the address of glBindBuffer, it shows

(gdb) p glBindBuffer
$1 = {<text variable, no debug info>} 0x7ffff7969f60 <glBindBufferARB>

But, the maps of this process does not load anything in that address:

/proc/<pid of gdb>$ cat maps

... snip ...

7fff5f652000-7fff5f673000 rw-p 00000000 00:00 0                          [stack]
7fff5f74d000-7fff5f74f000 r-xp 00000000 00:00 0                          [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]

user2548774 user2548774 · Accepted Answer · 2017-09-26T02:11:04

Seems the apis are written in assembly language, so no source can be displayed. Just set a breakpoint at glBindBuffer, then run, then the program will pause at the breakpoint, then type 'step' or 'next', you will step into the real function behind the api.

How to step into openGL APIs by using gdb?

1 Answers