Alan Modra <amo...@gmail.com> wrote on 2010/10/11 14:58:45:
>
> On Sun, Oct 10, 2010 at 11:20:06AM +0200, Joakim Tjernlund wrote:
> > Now I have had a closer look at this and it looks much like -fpic
> > on ppc32, you still use the GOT/TOC to load the address where the data is.
>
> No, with ppc64 -mcmodel=medium you use the GOT/TOC pointer plus an
> offset to address local data.
>
> > I was looking for true %pc relative addressing of data. I guess this is
> > really
> > hard on PowerPC?
>
> Yes, PowerPC lacks pc-relative instructions.
>
> > I am not sure this is all it takes to make -fpic to work with -mrelocatable,
> > any ideas?
>
> You might be lucky. With -mrelocatable, .got2 only contains
> addresses. No other constants. So a simple run-time loader can
> relocate the entire .got2 section, plus those locations specified in
> .fixup. You'll have to make sure gcc does the same for .got, and your
> run-time loader will need to be modified to handle .got (watch out for
> the .got header!).
Got it working now. It was just u-boot reloc routine I first failed
to extend properly to reloc *got too.
I think this is safe as one can mix fpic with fPIC and
mrelocatable is the same as fPIC+fixups.
Will you accept this patch into gcc?
Jocke
