This is the mail archive of the
binutils@sourceware.org
mailing list for the binutils project.
Re: Relocations against STN_UNDEF
On Fri, Sep 24, 2010 at 09:54:25AM +0200, Thomas Schwinge wrote:
> On 2010-09-24 00:12, Alan Modra wrote:
> > ARM fails because the arm backend specifically checks for undefined
> > local symbols. I'd say the arm backend check needs fixing (or
> > removing) rather than changing the common elflink code.
>
> Surely enough we could just change the ARM backend, but I'm not yet
> really convinced that this is the most appropriate approach: if we agree
> that BFD internally shall register STN_UNDEF with bfd_abs_section
> instead of bfd_und_section (as demonstrated in other parts of the code
> that I quoted),
What is done elsewhere to make ELF relocs fit into the BFD framework
isn't particularly relevant to the ELF linker.
> then why not make it like this during relocations
> processing, too?
Why do extra work just for ARM?
> Or is it that you think this change may be disruptive
> for other backends?
The thought had crossed my mind.
> >> I wonder why we need this code duplicated in (at least) two places; why
> >> do objdump and ld use different code paths for reading in relocations?
> >
> > Efficiency.
>
> Uhm, okay...
To expand a little, the general BFD code for reading relocs wants to
return them as an arelent array, using symbols from an asymbol *
array. By processing the relocs directly the ELF linker saves time
and memory; No need to convert ELF symbols to BFD asymbols, and no
need to set up an arelent array.
--
Alan Modra
Australia Development Lab, IBM