Re: [patch] solib-svr4.c - allow reading linkmap info from core without executable

[Aleksandar Ristovski <aristovski@qnx.com>]

Pedro Alves wrote:
>>    if (info->debug_base == 0 && svr4_have_link_map_offsets ())
>>      {
>> -      if (exec_bfd != NULL
>> +      if ((exec_bfd != NULL
>>           && bfd_get_flavour (exec_bfd) == bfd_target_elf_flavour)
>> +         || (core_bfd != NULL
>> +             && bfd_get_flavour (core_bfd) == bfd_target_elf_flavour))
>>         info->debug_base = elf_locate_base ();
>>      }
> 
> Are there live debugging cases (archs?, PIE?) (e.g., "target remote" 
> without specifying an executable) where letting elf_locate_base
> try to read the debug base from the target's auxv (scan_dyntag_auxv)
> will work?  It would mean that removing the exec_bfd checks instead
> of adding core_bfd checks, would still improve your case, while
> letting other cases benefit as well.
> 

Yes, in theory it should work as long as target_ops in 
question know how to read auxv (that is, as long as 
to_xfer_partial(ops, TARGET_OBJECT_AUXV,...) knows how to do 
it.)

I had internally made this change:

     {
-     if (exec_bfd != NULL
+      if ((exec_bfd != NULL
           && bfd_get_flavour (exec_bfd) == 
bfd_target_elf_flavour)
+          || exec_bfd == NULL)
         debug_base = elf_locate_base ();
     }
   return (debug_base);


But wanted to be more conservative for FSF, since I do not 
quite understand under which circumstances could we end up 
in solib-svr4, and not have "bfd_target_elf_flavour".


Thanks,

-- 
Aleksandar Ristovski
QNX Software Systems