[U-Boot] [PATCH] PowerPC: Change -fpic flag to -fPIC flag in the config.mk

[Joakim Tjernlund]

>
> Scott Wood <scottwood at freescale.com> wrote on 2012/04/26 23:26:52:
> >
> > On 04/26/2012 01:53 AM, Joakim Tjernlund wrote:
> > > Scott Wood <scottwood at freescale.com> wrote on 2012/04/25 21:01:00:
> > >>
> > >> On 04/18/2012 05:07 AM, Joakim Tjernlund wrote:
> > >>> Your linker file is buggy I think. I found u-boot-nand_spl.lds, is that the one?
> > >>
> > >> That's the one for the SPL part.
> > >
> > > OK, good.
> > >
> > >>
> > >>> Check out that files reloc part:
> > >>> .reloc : {
> > >>>       _GOT2_TABLE_ = .;
> > >>>       KEEP(*(.got2))
> > >>>       _FIXUP_TABLE_ = .;
> > >>>       KEEP(*(.fixup))
> > >>>    }
> > >>>    __got2_entries = (_FIXUP_TABLE_ - _GOT2_TABLE_) >> 2;
> > >>>    __fixup_entries = (. - _FIXUP_TABLE_) >> 2;
> > >>>
> > >>> Compare that with(from u-boot.lds):
> > >>>  .reloc   :
> > >>>   {
> > >>>     _GOT2_TABLE_ = .;
> > >>>     KEEP(*(.got2))
> > >>>     KEEP(*(.got))
> > >>>     PROVIDE(_GLOBAL_OFFSET_TABLE_ = . + 4);
> > >>>     _FIXUP_TABLE_ = .;
> > >>>     KEEP(*(.fixup))
> > >>>   }
> > >>>   __got2_entries = ((_GLOBAL_OFFSET_TABLE_ - _GOT2_TABLE_) >> 2) - 1;
> > >>>   __fixup_entries = (. - _FIXUP_TABLE_) >> 2;
> > >>
> > >> I notice a difference between u-boot.lds and u-boot-nand.lds -- the
> > >> latter (used for the main part of U-Boot when loaded from SPL) has:
> > >>
> > >>>   .reloc   :
> > >>>   {
> > >>>     KEEP(*(.got))
> > >>>     _GOT2_TABLE_ = .;
> > >>>     KEEP(*(.got2))
> > >>>     _FIXUP_TABLE_ = .;
> > >>>     KEEP(*(.fixup))
> > >>>   }
> > >>>   __got2_entries = (_FIXUP_TABLE_ - _GOT2_TABLE_) >> 2;
> > >>>   __fixup_entries = (. - _FIXUP_TABLE_) >> 2;
> > >>
> > >> Is this wrong as well?
> > >
> > > Yes, I think so.  This one does not care about the .got entries at all so I suspect
> > > never gcc's wont work.
> >
> > Thanks.
> >
> > I'm not entirely sure about the _GLOBAL_OFFSET_TABLE_ stuff, though --
> > what's wrong with the simpler version that uses _FIXUP_TABLE_?
>
> _GLOBAL_OFFSET_TABLE_ is a -fpic thing, it marks the beginning of reloc entrires and gcc/binutils
> defines it if there are -fpic relocs present. If -fpic is present, there is are some extra
> entrires. If no -fpic I need to manually recreate space, otherwise the reloc routine will be off.

PS. note the -1 diff too:
  __got2_entries = ((_GLOBAL_OFFSET_TABLE_ - _GOT2_TABLE_) >> 2) - 1;

 Jocke