Re: [Gcl-devel] plt.c and Mach-O ABI

[Aurelien Chanudet]

Hi Camm,

> Greetings! In 2.14.90.0.7 and earlier, I'd get a symbol table that
> looked like
>
> objdump -x foo_good_raw |grep UND
> 0804a7dc       F *UND*  00000018              __gmpz_fdiv_q_2exp
> 0804a7ec       F *UND*  00000030              __gmpz_set_si
> 0804a7fc       F *UND*  0000003e              usleep@@GLIBC_2.0
> 0804a80c       F *UND*  00000026              cos@@GLIBC_2.0
> 0804a81c       F *UND*  0000003a              rename@@GLIBC_2.0
> 0804a82c       F *UND*  0000006d              ferror@@GLIBC_2.0
> 0804a83c       F *UND*  00000053              sigaction@@GLIBC_2.0
> ...
>
> Now I get
>
> objdump -x foo_bad_raw | grep UND
> 00000000       F *UND*  00000018              __gmpz_fdiv_q_2exp
> 00000000       F *UND*  00000030              __gmpz_set_si
> 00000000       F *UND*  0000003e              usleep@@GLIBC_2.0
> 00000000       F *UND*  00000026              cos@@GLIBC_2.0
> 00000000       F *UND*  0000003a              rename@@GLIBC_2.0
> 00000000       F *UND*  0000006d              ferror@@GLIBC_2.0
> 00000000       F *UND*  00000053              sigaction@@GLIBC_2.0

So, undefined symbols are now being given null values by the ELF 
back-end.
When I started working on BFD, the same was true for the Mach-O 
back-end.
I modified this behavior so as to comply with the ELF behavior which I 
took
as a reference. This means that I'm entirely free as to what values 
undefined
symbols are being given.

> Would you have time to check what if any problems you have with the
> latest binutils ld?

So : no problems here since I'm controlling the behaviour.

> Do you have suggestions for portable ways of achieving this end?

I'll have to think it over but this looks like a real pain...