Re: Chicken-or-egg problem with shared libraries

[Daniel Jacobowitz <drow at false dot org>]

On Tue, May 23, 2006 at 02:04:26PM -0700, PAUL GILLIAM wrote:
> In solib-svr4.c (enable_break), GDB tries to set a breakpoint in the
> dynamic loader (at "_dl_debug_state") so that shared objects can be
> tracked as they are loaded and unloaded.
> 
> The problem (on gnu/linux PowerPC64 at least) is that the dynamic loader
> is it's self a shared object and its minimal symbols are not loaded when
> "enable_break" is called.  
> 
> I have two ideas for fixing this: 1) pre-load the dynamic loaders
> minimal symbols so that when "enable_break()" is called,
> "_dl_debug_state" will be found and all is well and 2) allow
> "enable_break()" to set a pending breakpoint.

I don't think you really understand the problem you're trying to fix -
what is it, by the way?  Is it related to Alan's comment earlier
about the function descriptor lookup?

Here's how it works today:

      bfd_get_section_contents (exec_bfd, interp_sect,
                                buf, 0, interp_sect_size);

      tmp_fd  = solib_open (buf, &tmp_pathname);
      if (tmp_fd >= 0)
        tmp_bfd = bfd_fopen (tmp_pathname, gnutarget, FOPEN_RB, tmp_fd);


          sym_addr = bfd_lookup_symbol (tmp_bfd, *bkpt_namep, SEC_CODE);
          if (sym_addr != 0)
            break;

-- 
Daniel Jacobowitz
CodeSourcery