Re: warning: Unable to find dynamic linker breakpoint function

[Adam Richard <g4c9z@unb.ca>]

Quoting Daniel Jacobowitz <drow@false.org>:

> On Thu, Dec 30, 2004 at 08:35:59PM -0400, Adam Richard wrote:
> > Quoting Daniel Jacobowitz <drow@false.org>:
> > 
> > > On Wed, Dec 29, 2004 at 05:33:04PM -0400, Adam Richard wrote:
> > > > I wonder if someone knows what the following warning means?  It appears
> whenever I
> > > use
> > > > the "run" command to start my program:
> > > > 
> > > > (gdb) run
> > > > Starting program: /home/adam/programming/programs/meals/meals
> > > > warning: Unable to find dynamic linker breakpoint function.
> > > > GDB will be unable to debug shared library initializers
> > > > and track explicitly loaded dynamic code.
> > > > 
> > > > I found a few posts related to it but few people seem to know what the warning
> > > message
> > > > itself means.
> > > 
> > > It means exactly what it says - GDB could not set the breakpoint that
> > > it uses for tracking things like dlopen().
> > > 
> > > I can't guess at causes, since you didn't tell us what your platform
> > > is.
> > 
> > Actually, the error message isn't really clear - I just looked up what dlopen does,
> but
> > I don't see what it has to do with breakpoints.  As to my platform, I'm using
> Gentoo
> 
> Nothing, on its own.  GDB uses a breakpoint to be able to support
> debugging programs which use dlopen.
> 
That doesn't really make sense to me.  Setting a breakpoint *is* a debugging task.  Why
does it need to set a breakpoint in order to debug?

> > Linux, kernel 2.6.9, on an AMD Athlon XP processor.  I read somewhere that it
> might
> > have to do with a stripped gdb but I don't understand why I can't have a stripped
> gdb
> > so I'm hoping for an explanation.
> 
> Not a stripped GDB, a stripped dynamic linker (/lib/ld-linux.so.2).

OK, why does a stripped dynamic linker impair debugging?  I noticed that that file is
part of the glibc package, and I can see why stripping it would prevent being able to
step into its functions for any program which depends on it (which is most programs). 
But I still don't understand your explanation.

> -- 
> Daniel Jacobowitz
> 


---
Adam
http://personal.nbnet.nb.ca/aerichar/