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Can I link a.out .o with ELF?

Ian Lance Taylor ian@zembu.com
Mon Jun 5 09:49:00 GMT 2000 
   Date: Tue, 6 Jun 2000 00:28:01 +1000 (EST)
   From: Alan Modra <alan@linuxcare.com.au>

   Index: elflink.h
   ===================================================================
   RCS file: /cvs/src/src/bfd/elflink.h,v
   retrieving revision 1.58
   diff -u -p -r1.58 elflink.h
   --- elflink.h	2000/05/30 20:51:36	1.58
   +++ elflink.h	2000/06/05 14:23:33
   @@ -1741,6 +1741,20 @@ elf_link_add_object_symbols (abfd, info)
			 ht = (struct elf_link_hash_entry *) hi->root.u.i.link;
			 (*bed->elf_backend_copy_indirect_symbol) (ht, hi);

   +		      if ((hi->elf_link_hash_flags & ELF_LINK_NON_ELF) != 0)
   +			{
   +			  if (dynamic)
   +			    hi->elf_link_hash_flags |=
   +			      ELF_LINK_HASH_DEF_DYNAMIC;
   +			  else
   +			    hi->elf_link_hash_flags |=
   +			      ELF_LINK_HASH_DEF_REGULAR;
   +
   +			  ht->elf_link_hash_flags |=
   +			    (ELF_LINK_HASH_REF_REGULAR
   +			     | ELF_LINK_HASH_REF_REGULAR_NONWEAK);
   +			}
   +
			 /* See if the new flags lead us to realize that
			    the symbol must be dynamic.  */
			 if (! dynsym)

I don't understand why you would ever want to set DEF_DYNAMIC here.
You should only get ELF_LINK_NON_ELF when the symbol appears in a
non-ELF file.  The ELF linker does not support linking against a
non-ELF dynamic library.

It should only be necessary to set DEF_REGULAR if the symbol is in
fact defined in a non-ELF file.  Similarly, it should only be
necessary to set REF_REGULAR and REF_REGULAR_NONWEAK if the symbol is
referenced in a non-ELF file.  The code above may well be correct on
this, although I don't really understand why we need to set them here
as opposed to various other places.

   @@ -3283,11 +3297,15 @@ elf_fix_symbol_flags (h, eif)
	 struct elf_link_hash_entry *h;
	 struct elf_info_failed *eif;
    {
   +  struct elf_link_hash_entry *ho = h;
   +  while (h->root.type == bfd_link_hash_indirect)
   +    h = (struct elf_link_hash_entry *) h->root.u.i.link;
   +
      /* If this symbol was mentioned in a non-ELF file, try to set
	 DEF_REGULAR and REF_REGULAR correctly.  This is the only way to
	 permit a non-ELF file to correctly refer to a symbol defined in
	 an ELF dynamic object.  */
   -  if ((h->elf_link_hash_flags & ELF_LINK_NON_ELF) != 0)
   +  if ((ho->elf_link_hash_flags & ELF_LINK_NON_ELF) != 0)
	{
	  if (h->root.type != bfd_link_hash_defined
	     && h->root.type != bfd_link_hash_defweak)

I don't think it is right to change h here.  elf_fix_symbol_flags
should get called for every h.

I don't quite see why you are doing this.  I assume it has something
to do with the call from elf_link_assign_sym_version.  But I don't see
why it works.

What happens if you just patch elf_link_assign_sym_version to work on
NON_ELF symbols as well as DEF_REGULAR symbols?

Ian
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