[FFmpeg-devel] [PATCH] put dispatch_tab* in .data (was Re: Build problem)

[Diego Biurrun]

On Sun, Feb 08, 2009 at 07:10:33PM +0100, Dominik 'Rathann' Mierzejewski wrote:
> On Wednesday, 04 February 2009 at 11:00, Reimar D?ffinger wrote:
> > On Wed, Feb 04, 2009 at 09:25:46AM +0000, M?ns Rullg?rd wrote:
> > > Art Clarke <aclarke at xuggle.com> writes:
> > > 
> > > > I installed yasm on our Mac build boxes today, and noticed the
> > > > following error doing x86_64 builds:
> > > >
> > > >>> ld: pointer in read-only segment not allowed in slidable image, used in dispatch_tab_sse from libavcodec/x86/fft_mmx.o
> > > >
> > > > I was wondering if people already knew why this occurs (a perusal of
> > > > the archives suggested not).  If I don't have yasm installed or
> > > > available on the path the build works fine.  Any thoughts or anyone
> > > > else seeing this?
> > > 
> > > Yes, Apple is stupid as usual.  What that error message means is that
> > > it doesn't allow relocations in read-only sections, which is utterly
> > > silly.
> > 
> > Well, in that specific case it might also be because the data gets
> > placed in .text and not .rodata on OSX, supposedly because of alignment
> > issues.
> > Try changing libavcodec/x86/x86inc.asm to use .rodata or .data, maybe
> > one of them work...
> 
> FWIW, the original code results in a shared library with text relocations
> in read-only segment on x86_64. Putting dispatch_tab* in .rodata doesn't
> change that, because both .text and .rodata end up in the same segment
> that has READ and EXECUTE bits set. Putting dispatch_tab* in .data
> gets rid of them. IOW, what about the attached patch?
> 
> +++ ffmpeg-20090204/libavcodec/x86/fft_mmx.asm	2009-02-08 18:51:15.000000000 +0100
> @@ -446,8 +446,9 @@ fft %+ n %+ %3%2:
>  %endrep
>  %undef n
>  
> -align 8
> +section .data
>  dispatch_tab%3%2: pointer list_of_fft
> +section .text

What about this?

Diego