Re: binutils 2.20.1 on irix 6.5.22 _rld_new_interface question

[Richard Sandiford <rdsandiford at googlemail dot com>]

Hi David,

Thanks for the report.  It's good to hear that recent a GNU ld still
works reasonably well on IRIX 6.5.  It's many years since I last had
access to an IRIX box and tried this myself.  But there were quite
a few problems that needed to fixed around the 2.16 release, and I was
worried that might be true again now.

"David E. Cross" <crossd@cs.rpi.edu> writes:
> Running binutils 2.20.1 on irix 6.5.22 with great success, moreso then 
> native Irix ld in fact.
>
> However I have come across one bug that I am scratching my head over how 
> to fix.
>
> Irix has no "dladdr" funtion, instead they tell you to call 
> _rld_new_interface with certain parameters and it will do the same things. 
> The problem is that _rld_new_interface is a special symbol that is within 
> the runtime linker and not in any library.
>
> There is some special handling in bfd/elfxx-mips.c for this already, that 
> ammounts to basically ignoring the symble.  This works fine for the 99% of 
> applications that don't acually use the symbol (and allows things to link 
> with libc).. However for programs that DO use it, a  undef symbol needs to 
> be inserted into the symbol table as a placeholder.  Like _I THINK_
> is done with __rld_obj_head.  I have tried duplicating the part of the 
> code that adds __rld_obj_head without success; (modifiying it to set 
> BSF_FUNCTION and ST_FUNC).. I am obviously just stabbing in the dark here 
> and I hope someone could help me out.. I have some symbol tables listed 
> below:

I think __rld_obj_head is a bit different.  IIUC, it's defined in crt1.o,
so is present in effectively all executable links.  (Please correct me
if I'm wrong on that.  Like I say, it's been a long time.)

The add_symbol hack for _rld_new_interface is gross.  It looks like
it should only trigger for DSO inputs though.  If you have a regular
.o that references _rld_new_interface, it should get processed in the
normal way.

> Symbols from /lib32/libc.so.1:
>
> [Index]   Value      Size    Type  Bind  Other     Shndx   Name
>
> [6243]  |         0|       0|FUNC |GLOB |DEFAULT  |UNDEF  |_rld_new_interface
>
>
> dso_dlfcn  (when linked with Irix ld)
>
> [46]    | 268438512|       0|FUNC |GLOB |DEFAULT  |UNDEF  |_rld_new_interface
>
> dso_dlfcn.o (when compiled with Irix cc)
>
> [6]     |         0|       0|FUNC |GLOB |DEFAULT  |UNDEF  |_rld_new_interface
>
>
> dso_dlfcn.o (when compiled with gcc)
>
> [11]    |         0|       0|OBJT |GLOB |DEFAULT  |UNDEF  |_rld_new_interface

Could you also show the relocations against _rld_new_interface in
dso_dlfcn.o?  Like you say, the OBJT thing is a bit odd...

Richard