Relocations against STN_UNDEF

[Alan Modra]

On Thu, Sep 23, 2010 at 05:37:01PM +0200, Thomas Schwinge wrote:
>       1469        if (ELF_R_SYM (rela.r_info) == 0)
>       1470          relent->sym_ptr_ptr = bfd_abs_section_ptr->symbol_ptr_ptr;
> 
> That is, if the index is zero -- should use STN_UNDEF here instead of the
> zero constant, I'd say?

Yes.

>     $ "$PWD"_install/bin/*-ld -o bl_ABS bl_ABS.o
>     /scratch/thomas/binutils/HEAD_build_arm-none-eabi_install/bin/arm-none-eabi-ld: warning: cannot find entry symbol _start; defaulting to 0000000000008000
>     bl_ABS.o:(.text+0x0): undefined reference to `no symbol'

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.

> 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.

-- 
Alan Modra
Australia Development Lab, IBM