Re: gdb compile for powerpc64 target - Could not find symbol ".TOC."

[will schmidt <will_schmidt@vnet.ibm.com>]

On Sat, 2021-07-10 at 10:31 +0930, Alan Modra wrote:
> On Fri, Jul 09, 2021 at 11:51:35AM -0500, will schmidt wrote:
> > I've made some local changes so I'm now calling bfd_set_gp_value
> > when
> > the ".TOC." symbol is handled in compile_object_load. 
> > i.e. 
> >       if (strcmp (sym->name, ".TOC.") == 0)
> >         bfd_set_gp_value(abfd.get(), sym->value);
> > 
> > This is either wrong, or insufficient.  :-)
> 
> Symbol value here is section relative.  You need to add the symbol
> section vma, which is set by setup_sections_data::setup_one_section.


So is that creating a new section named vma, or updating one of the
existing sections?
I see that we currently call setup_one_section for all(?) of the
sections , the full list being .data, .bss, .toc, .debug_info,
.debug_abbrev, .debug_aranges, .debug_line, .debug_str, .comment,
.note.GNU-stack, .debug_frame.   
It appears we call bfd_set_section_vma (sect, m_last_size);  for each
of those.
I can't immediately tell if or how I should try adding a call to
bfd_set_gp_value from within there.    (how to get to the parent abfd
from within a scope that only deals with the section?)
If/when I sort that part out, I'm still not sure what value I should be
trying to set that gp value to.  :-)

> 
> If that doesn't help, I would run gdb under gdb with a breakpoint on
> ppc64_elf_toc_reloc looking to see whether that function is using the
> value you expect given your bfd_set_gp_value call.

At the moment (before further changes)..


(gdbouter) p TOCstart
$42 = 01000000002200000


Thanks
-Will