Meaningful backtrace from your debugger if you break on the gdk_x_error

Paul Pluzhnikov
Wed Dec 16 05:32:00 GMT 2009

On Mon, Dec 14, 2009 at 7:45 AM, Elvis Wong <> wrote:
> Hi all, im new to gdb.
> I try to debug an application that crash;
> here what i try;
> $ gdb --args test --sync
> (gdb) break gdk_x_error
> Function "gdk_x_error" not defined.
> Make breakpoint pending on future shared library load? (y or [n]) y
> Breakpoint 1 (gdk_x_error) pending
> (gdb) run
> ....snip....
> The program 'test' received an X Window System error.
> This probably reflects a bug in the program.
> The error was 'BadAlloc (insufficient resources for operation)'.
>  (Details: serial 15391 error_code 11 request_code 53 minor_code 0)
>  (Note to programmers: normally, X errors are reported asynchronously;
>   that is, you will receive the error a while after causing it.
>   To debug your program, run it with the --sync command line
>   option to change this behavior. You can then get a meaningful
>   backtrace from your debugger if you break on the gdk_x_error() function.)
> [Thread 0xb7e1ab70 (LWP 7469) exited]
> [Thread 0xb7125b70 (LWP 7470) exited]
> [Thread 0xb691fb70 (LWP 7471) exited]
> [Thread 0xb611eb70 (LWP 7472) exited]
> [Thread 0xb3e02b70 (LWP 7482) exited]
> [Thread 0xb57ffb70 (LWP 7485) exited]
> [Thread 0xb3601b70 (LWP 7486) exited]
> Program exited with code 01.
> (gdb) bt
> No stack.

The program has *exited*, there is no stack!

> (gdb) i r
> The program has no registers now.
> How can i catch this bug?

Set a breakpoint on main. Run. When the breakpoint is hit, set a
breakpoint on gdk_x_error which by that time should be known to GDB
(i.e. you should not get a "pending" breakpoint at that point). If
gdk_x_error isn't known, you probably have stripped gdk libraries; try
setting breakpoint on _XError instead.

Good luck!
Paul Pluzhnikov

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