multilib question

Ralf Corsepius ralf.corsepius at
Thu Nov 10 07:38:25 UTC 2005

On Thu, 2005-11-10 at 14:24 +0800, Paul Whitfield wrote:
> Till Straumann wrote:
> > I want to build gcc/newlib with the following variants:
> > 
> > -mcpu=860 -soft-float
> > -mcpu=603e -Dmpc8260
> > -mcpu=604
> > -mcpu=7400 -mabi=altivec -maltivec -mvrsave=yes
> > -mcpu=7400 -mabi=altivec -maltivec -mvrsave=no
> > -mcpu=7400 -mabi=altivec -mno-altivec
> > 
> > how do I have to set the MULTILIB_xxx variables in 't-rtems' ?
> > 
> Hi Till,
> I asked a similar question a long time ago, and received
> no answer, leading me to believe that it was not
> possible to limit/change the multi lib variants.
Well, you have the sources and you have the documentation. So nothing
prevents you from digging out how things actually work yourself.
Also, I recall having answered this question several times.

The basic working principles are quite simple, but the details, esp. on
the powerpc are quite complicated, not worth mentioning the implications
changing multilibs has on RTEMS (There have been cases, where such
implications had been discovered months after multilibs had been

Furthermore, IMO, most people asking for "custom multilibs" probably
vastly underestimate the effort related to implementing them. You should
realize that, depending on what you intend, the effort is in the order
of few days up to several weeks. Therefore, I generally don't encourage
users to try implementing customized multilibs, but encourage them to
use the official toolchains.

If your only objective is to reduce the number of multilibs inside of
RTEMS, have a look into RTEMS's There you can filter out
multilib variants you're not interested in.


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