Re: where do I figure out "relocation R_X86_64_PC32" errors

["H. J. Lu" <hjl at lucon dot org>]

On Sun, Sep 17, 2006 at 09:27:29PM -0400, sean wrote:
> Alan Modra wrote:
> >On Sun, Sep 17, 2006 at 05:05:14PM -0400, sean wrote:
> >
> >>H. J. Lu wrote:
> >>
> >>>On Sun, Sep 17, 2006 at 10:38:23AM -0400, sean wrote:
> >>>
> >>>>mmx_00ffw is just a constant in yuv2rgb.c:
> >>>>
> >>>>uint64_t attribute_used __attribute__((aligned(8))) 
> >>>>mmx_00ffw = 0x00ff00ff00ff00ffULL;
> >
> >
> >The trouble is that this variable is used in asm statements using rip
> >addressing, and the variable is global.  ELF shared libraries have
> >particular rules regarding global symbol resolution;  A global symbol
> >in a shared library may be overridden by the same symbol in the main
> >app code (or another shared lib).  rip addressing won't work in this
> >situation for two reasons: a) the rip offset is in read-only code, so
> >relocating the offset means the library can't share that page of text,
> >and more seriously, b) the rip offset is only 32-bit so might not
> >reach to the app symbol or another library sym (64-bit address space).
> >
> >There is a simple fix.  Add __attribute__ ((hidden)) to the variable
> >definition to make it local to the shared library.
> >
> 
> Nope. Same error message.
> 
> grep 00ffw ffmpeg/libswscale/yuv2rgb.c
> uint64_t attribute_used __attribute__((aligned(8))) 
> __attribute__((hidden)) mmx_00ffw = 0x00ff00ff00ff00ffULL;

It should be __attribute__((visibility("hidden"))).


H.J.