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Re: Difference between --oformat binary, and objcopy -O binary of --oformat elf32-i386
On Wed, Jul 20, 2016 at 08:08:22AM -0700, H.J. Lu wrote:
> On Tue, Jul 19, 2016 at 5:33 PM, Alan Modra <firstname.lastname@example.org> wrote:
> > On Tue, Jul 19, 2016 at 07:22:36AM -0700, H.J. Lu wrote:
> >> > HJ, it would be nice if x86 implemented something like elf32-ppc.c
> >> > ppc_elf_unhandled_reloc to give an error at link time for all the
> >> > relocs that the generic linker can't handle.
> >> >
> >> I see:
> >> HOWTO (R_PPC_TLSLD,
> >> 0, /* rightshift */
> >> 2, /* size (0 = byte, 1 = short, 2 = long) */
> >> 32, /* bitsize */
> >> FALSE, /* pc_relative */
> >> 0, /* bitpos */
> >> complain_overflow_dont, /* complain_on_overflow */
> >> bfd_elf_generic_reloc, /* special_function */
> >> "R_PPC_TLSLD", /* name */
> >> FALSE, /* partial_inplace */
> >> 0, /* src_mask */
> >> 0, /* dst_mask */
> >> FALSE), /* pcrel_offset */
> >> Can generic linker handle R_PPC_TLSLD?
> > Nope. However, this one is a marker reloc (src_mask and dst_mask both
> > 0 result in no relocation) so it is OK to ignore.
> Can bfd_perform_relocation handle ELF relocations which aren't
> one of
I assume you meant to ask "Can bfd_elf_generic_reloc handle ..".
The answer is, yes, it can handle a lot more, but it's true that only
simple relocs like the above are supported. Relocs with an implicit
symbol reference (eg. GOT relocs implicitly subtract
_GLOBAL_OFFSET_TABLE_) or are section relative (eg. SECTOFF relocs),
or build tables (eg. GOT, PLT relocs) or have split fields or
otherwise modify the insn in odd ways, are not supported.
Theoretically, I suppose you could even support GOT relocs with a
complex special_function but the effort isn't worth it.
Australia Development Lab, IBM