Single stepping and "no line information"

Single stepping and "no line information"

[Stefano Sabatini]

I'm debugging an application which use a shared lib.

That library has been compiled on my system, and I added to the CFLAGS
used the -ggdb -O0 flags, so I'm quite sure that lib should contain
the source line symbol informations.

Nonetheless when I try to step into the library functions I get:

(gdb) s
Single stepping until exit from function su_clone_start, 
which has no line number information.

stefano@geppetto ~/s/ptlib> gdb --version
GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i486-linux-gnu".

Why gdb can't find the source line informations?

How can I verify (e.g. with a commandline tool) wether that
information is present directly analyzing the library files?

TIA.

Best regards.

Re: Single stepping and "no line information"

[Stefano Sabatini]

On date Monday 2008-09-08 15:39:53 +0200, Stefano Sabatini wrote:
> I'm debugging an application which use a shared lib.
> 
> That library has been compiled on my system, and I added to the CFLAGS
> used the -ggdb -O0 flags, so I'm quite sure that lib should contain
> the source line symbol informations.
> 
> Nonetheless when I try to step into the library functions I get:
> 
> (gdb) s
> Single stepping until exit from function su_clone_start, 
> which has no line number information.
> 
> stefano@geppetto ~/s/ptlib> gdb --version
> GNU gdb 6.8-debian
> Copyright (C) 2008 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "i486-linux-gnu".
> 
> Why gdb can't find the source line informations?
> 
> How can I verify (e.g. with a commandline tool) wether that
> information is present directly analyzing the library files?

I tried with:
nm --line-numbers libfoo.so | grep foo

and indeed I get the symbol with its line and file information.

Could it be a gdb bug?

Regards.

Re: Single stepping and "no line information"

[Paul Pluzhnikov]

On Mon, Sep 8, 2008 at 6:39 AM, Stefano Sabatini
<stefano.sabatini-lala@poste.it> wrote:
>
> I'm debugging an application which use a shared lib.
>
> That library has been compiled on my system, and I added to the CFLAGS
> used the -ggdb -O0 flags, so I'm quite sure that lib should contain
> the source line symbol informations.
>
> Nonetheless when I try to step into the library functions I get:
>
> (gdb) s
> Single stepping until exit from function su_clone_start,
> which has no line number information.

What is the name of that shared library and what does 'info shared' say?

> Why gdb can't find the source line informations?

Not enough info to tell yet.

> How can I verify (e.g. with a commandline tool) wether that
> information is present directly analyzing the library files?

readelf -w /path/to/shlib then look for "Line Number Statements"
corresponding to su_clone_start.

Cheers,
--
Paul Pluzhnikov