Re: Contribution: Intel's iWMMXt processor

[Richard Earnshaw <rearnsha at arm dot com>]

> > Hi Guys,
> > 
> >   I am applying patches to the binutils sources to add support for
> >   Intel's iWMMXt processor - an ARM variant.  The ChangeLogs are below
> >   and a compressed patch is attached.
> 
> This has completely broken linking for non-xscale systems.  How can the 
> following possibly work?
> 
> 
>       if (   bfd_get_mach (obfd) == bfd_mach_arm_XScale
>           && bfd_get_mach (ibfd) == bfd_mach_arm_iWMMXt)
>         bfd_set_arch_mach (obfd, bfd_get_arch (obfd), bfd_mach_arm_iWMMXt);
>       else if (   bfd_get_mach (ibfd) != bfd_mach_arm_XScale
>                || bfd_get_mach (obfd) != bfd_mach_arm_iWMMXt)
>         {
>           bfd_set_error (bfd_error_wrong_format);
> 
> R.
> 

Actually, it's a combination of all the areas related to this.

1) The assembler sets the architecture to v5e if the user hasn't specified 
any particular architecture.   It should probably be set to unknown.
2) The bit of code above should be able to combine files with different 
architecture specifications with the result being the most specific 
architecture requested (provided they are compatible); except that 
unknown+anything is always unknown, unless some command-line option forces 
it otherwise.
3) I also don't like the fact that it is directly exporting the internal 
bfd numbers, which haven't been logically selected.  If we must do 
something like this, it should be based on names and the tools should map 
the names onto internal numbers as files are read and written.

Finally, the use of .note.arm.ident for a GNU extension is a really BAD 
idea.  This should have "gnu" somewhere in the note name.

All in all, I think trying to do this this way is dangerous and is going 
to lead to massive problems in the near future.  Can we please revert this 
bit?

R.