Re: patch to add QNX NTO i386 support

["Kris Warkentin" <kewarken at qnx dot com>]

> > #define HANDLE_SVR4_EXEC_EMULATORS 1
> > #include "solib.h" /* shared lib support */
>
> Including solib.h is fine.  However I wonder why you need
> HANDLE_SVR4_EXEC_EMULATORS.  AFAIK this deals with Solaris BCP
> (running SunOS 4 a.out files on Solaris 2 a.k.a. SunOS 5).  What is
> its relevance on QNX?  Could this be the reason that you need to set
> SOLIB_BKPT_NAME?

I've discovered why HANDLE_SVR4_EXEC_EMULATORS is needed but I'm not sure of
the correct way to fix it.  The relevant code is from solib-svr4.c below.  A
typical remote qnx debugging session would be something like this:

kewarken@CATDOG ~/test
$ ntox86-gdb
GNU gdb 5.2.1qnx-326 QNX Neutrino 6.2.1
Copyright 2002 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "--host=i686-pc-cygwin --target=ntox86".
(gdb) target qnx ren:10000
Remote debugging using ren:10000
(gdb) sym blah
Reading symbols from blah...done.
(gdb) upload blah /tmp/blah
(gdb) r /tmp/blah
Starting program:  /tmp/blah
(gdb) b main
Breakpoint 1 at 0x8048402: file blah.c, line 10.
(gdb) c
Continuing.

Breakpoint 1, main () at blah.c:10
10              func();

The problem that we're running into is that exec_bfd is NULL in the code
below so we fall back on the 'hard way' which is not really necessary (if
exec_bfd is set).  On the native qnx gdb, this isn't a problem because
exec_bfd is set when main() calls attach_command() which calls
exec_file_attach().  What I'd like to know is at what point should I stuff
exec_bfd?  In the case of remote debugging, the file with the symbols is
'/home/kewarken/test/blah' and the file being run (on the remote) is
/tmp/blah.  We need to set exec_bfd to point to the same file as the one
we've read symbols from but the question is, when and where?

cheers,

Kris

static CORE_ADDR
locate_base (void)
{
  if (debug_base == 0)
    {
      if (exec_bfd != NULL
   && bfd_get_flavour (exec_bfd) == bfd_target_elf_flavour)
 debug_base = elf_locate_base ();
#ifdef HANDLE_SVR4_EXEC_EMULATORS
      /* Try it the hard way for emulated executables.  */
      else if (!ptid_equal (inferior_ptid, null_ptid) &&
target_has_execution)
 proc_iterate_over_mappings (look_for_base);
#endif
    }
  return (debug_base);
}