Re: ld's targets vs emulations (intending to link EFI binaries on Linux)

["Jan Beulich" <JBeulich@novell.com>]

>>> On 12.05.11 at 13:05, Nick Clifton <nickc@redhat.com> wrote:
Hi Nick,

>> Anyway, while for i386 to build a linker that can build both ELF
>> and full-featured PE, all it takes is an extra configure option
>> (--enable-target=i386-pe or some such), for x86-64 to be able
>> to do the same one needs to first introduce such a bfd and
>> linker target. Would a change like the below be acceptable for
>> mainline?
>>
>> --- binutils-2.21/bfd/config.bfd
>> +++ 2.21/bfd/config.bfd
>> @@ -632,7 +632,7 @@ case "${targ}" in
>>       targ_selvecs="bfd_elf32_i386_vec i386linux_vec i386pei_vec 
> x86_64pei_vec bfd_elf64_l1om_vec"
>>       want64=true
>>       ;;
>> -  x86_64-*-mingw*)
>> +  x86_64-*-mingw* | x86_64-*-pe | x86_64-*-pep )
>>       targ_defvec=x86_64pe_vec
>>       targ_selvecs="x86_64pe_vec x86_64pei_vec bfd_elf64_x86_64_vec 
> bfd_elf64_l1om_vec i386pe_vec i386pei_vec bfd_elf32_i386_vec"
>>       want64=true
>> --- binutils-2.21/ld/configure.tgt
>> +++ 2.21/ld/configure.tgt
>> @@ -274,6 +274,9 @@ i[3-7]86-*-cygwin*)	targ_emul=i386pe ;
>>   			test "$targ" != "$host"&&  LIB_PATH='${tooldir}/lib/w32api' ;;
>>   i[3-7]86-*-mingw32*)	targ_emul=i386pe ;
>>   			targ_extra_ofiles="deffilep.o pe-dll.o" ;;
>> +x86_64-*-pe | x86_64-*-pep) targ_emul=i386pep ;
>> +			targ_extra_emuls=i386pe ;
>> +			targ_extra_ofiles="deffilep.o pep-dll.o pe-dll.o" ;;
>>   x86_64-*-mingw*)	targ_emul=i386pep ;
>>   			targ_extra_emuls=i386pe
>>   			targ_extra_ofiles="deffilep.o pep-dll.o pe-dll.o" ;;
> 
> This is OK,

Thanks, committed.

>> What the original question boils down to is whether i386 and x86_64
>> Linux selections shouldn't default to enable PE emulations (and not
>> just the respective BFD targets).
> 
> Hmm, well you are welcome to try it out, but I think that you will start 
> to run into problems with the relocations.

Sure, it won't work any better than it does when enabling the extra
emulation on the configure command line (and it's not just the
relocations - I also notice that all non-global symbols get lost). When
I can spare some cycles for this, I'd certainly be interested in
improving the situation.

The question just was whether that enabling shouldn't be the default
irrespective of the current shortcomings (eventually for all
architectures that support Linux booting from EFI).

Jan