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Re: Bug#572420: Please change this bug to libsdl1.2debian

On Tue, Apr 13, 2010 at 11:57:35 +0200, Michel Dänzer wrote:

> Can the problem be worked around by running the affected apps with the
> environment variable SDL_ALTIVEC_BLIT_FEATURES=0?
> If yes, SDL_HasAltiVec() may just incorrectly return true on
> non-Altivec-capable systems.
> If no, apparently the Altivec specific code isn't separated enough yet
> in the SDL build / packaging. Should be solvable either by moving all
> the Altivec specific code to separate .c files and only setting the
> Altivec specific compiler flags for those, or by building the binaries
> once with and without Altivec support each and installing the Altivec
> enabled binaries in /usr/lib/altivec/.
As far as I can tell, if libsdl detects altivec compiler support, it
builds *everything* with -maltivec, not just the files which make use of
altivec intrinsics.  It would probably be best to fix that by moving the
altivec-using functions from src/video/SDL_blit_*.c to their own file,
and only compile that file with -maltivec, so gcc doesn't generate
altivec instructions for the rest of the library.  For squeeze however,
I think I'll nmu with altivec disabled, unless some powerpc person wants
to provide a patch for the 'two passes' suggestion.


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