Relocs against unalloced sections in shared libraries

Daniel Jacobowitz drow@mvista.com
Fri Jan 10 15:10:00 GMT 2003


On Fri, Jan 10, 2003 at 04:07:48PM +0100, Andreas Schwab wrote:
> Daniel Jacobowitz <drow@mvista.com> writes:
> 
> |> On Fri, Jan 10, 2003 at 03:24:20PM +0100, Andreas Schwab wrote:
> |> > Daniel Jacobowitz <drow@mvista.com> writes:
> |> > 
> |> > |> On Thu, Jan 09, 2003 at 04:39:08PM -0800, Geoff Keating wrote:
> |> > |> > > From: Andreas Schwab <schwab@suse.de>
> |> > |> > > Date: 10 Jan 2003 01:29:50 +0100
> |> > |> > 
> |> > |> > > Geoff Keating <geoffk@geoffk.org> writes:
> |> > |> > > 
> |> > |> > > > Isn't this necessary for proper handling of DWARF2 debug information?
> |> > |> > > 
> |> > |> > > The debugger will know which bytes to relocate by looking at the
> |> > |> > > structure while reading the debug information from a shared library.
> |> > |> > 
> |> > |> > Hmmm.  Have you asked the GDB people about this?  I believe the
> |> > |> > conclusion was that it kind-of does this now, and it kind-of works,
> |> > |> > but in the long run it should be looking at the relocations.
> |> > |> 
> |> > |> Yes.  I don't know if it's possible to reproduce the situation in a
> |> > |> shared library on PPC (I haven't tried) but there are ET_REL objects
> |> > |> on PPC that _can not_ be debugged without properly obeying the
> |> > |> relocation information.  That's because there can be relocations
> |> > |> against variables instead of against section symbols.
> |> > 
> |> > We are talking about ET_DYN objects, where this is a non-issue.  Of
> |> > course, ET_REL object continue to contain the full relocation information.
> |> 
> |> Is it?
> 
> What is "it" refering to?

"this" above, the non-issue.

> |> Will all these relocations be resolved to section+offset?
> 
> The only relocations that would occur in a shared library are
> R_PPC_RELATIVE relocations.

OK, thanks.  I'll punt on this discussion then; GDB doesn't care either
way.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer



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