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Re: PPC CFLAGS [Was: Re: rpms/openarena/devel openarena.spec, 1.1, 1.2]



On Fri, 2007-01-12 at 21:29 +0800, David Woodhouse wrote:
> On Fri, 2007-01-12 at 14:08 +0100, Axel Thimm wrote:
> > What is the difference? If a unit has been compiled with altivec and
> > the resulting binary calls something in this unit on a non-altivec
> > system your binary will still boom, or not?
> > 
> > E.g. if we need to support non-altivec system then altivec must be
> > strictly banned unless - as you wrote - the software is smart enough
> > to do it at runtime (which is seldom).
> 
> Not _so_ seldom, in Altivec-capable code. Programs like xine and mplayer
> get it right. There are parts which are compiled with -maltivec but
> they're conditionally called.

Conditionally at compile-time or at run-time?

Normally, packages trying squeeze out cpu-variant specifics apply
compile-time conditionals. i.e. they break on some cpu-variants at
run-time (The reason why rtems has an -maltivec multilib ;) ).

> > Are there relevant numbers of G3 systems out there that we want to
> > support (excluding the unreleased G3+altivec chip)?
> 
> I don't know about G3 but there are relevant numbers of Altivec-less
> systems out there, since that includes POWER -- and in particular a
> bunch of our build machines.
> 
> Do not build packages which use Altivec unconditionally -- always make
> it check at runtime, just as we do for MMX/SSE/etc. 
OK, that's what I wanted to hear.

=> This package is broken, -maltivec is forbidden.

Ralf



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