[FFmpeg-devel] PIC and YASM

[David Conrad]

On Nov 8, 2009, at 9:35 AM, M?ns Rullg?rd wrote:

> Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
>
>> On Sun, Nov 08, 2009 at 01:47:20PM +0000, M?ns Rullg?rd wrote:
>>> Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
>>>
>>>> Hello,
>>>> I have been trying to figure out some compilation issues with  
>>>> hardened
>>>> gentoo on AMD64 and they all come down to YASM.
>>>> Several issues:
>>>> -DPIC is and must be added explicitly to the yasm flags.
>>>> in particular:
>>>> --enable-pic will not add -DPIC to YASMFLAGS, nor will the  
>>>> enable_pic
>>>> function. --enable-shared will though.
>>>
>>> That's easy to fix.  Does this work better?
>>
>> Probably, though why not just put it in the enable_pic function?
>
> Why litter a generic function with x86-specifics?
>
>> (x86inc.asm will unset it by itself where it is not supported)
>> I also suspect that my proposal will allow to get rid of that
>> "enable pic" hack for OpenBSD
>
> OpenBSD requires PIC.  Always.  End of story.
>
>> and the macho64 special-case.
>
> I don't know the story behind that one.

Mach-o doesn't support 32-bit absolute relocations on x86_64, only 64- 
bit absolute which most instructions don't support.

http://opensource.apple.com/source/xnu/xnu-1456.1.26/EXTERNAL_HEADERS/mach-o/x86_64/reloc.h