multilib question

[Ralf Corsepius]

On Thu, 2005-11-10 at 09:07 -0800, Till Straumann wrote:
> Ralf Corsepius wrote:
> > On Wed, 2005-11-09 at 22:06 -0800, 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' ?
> > 
> 
> OK, let me simplify my question:
> 
> I want something like MULTILIB_EXTRA_OPTS but it should only
> apply to one specific variant. E.g., -mcpu=7400 should always
> activate -mabi=altivec but -mabi=altivec should not be active
> on other cpus.
Generally speaking, this means adding an extra element to the vector of
multilibs.

I.e.
* to extend MULTILIB_OPTIONS and MULTILIB_DIRNAMES by one element,
* to extend MULTILIB_EXCEPTIONS to remove all those permutations of
flags you don't want.

It's basically the same as soft-floats are implemented in t-rtems (some
cpus have both soft-float/fpu variants, some cpus have fpu variants only
(imply hard-float), some variants have soft-float only (imply
soft-float).

Finally, for some reasons I never understood, powerpc-rtems-gcc has
-mno-eabi in its MULTILIB_EXTRA_OPTS, which I am not sure whether it
interferes with -mabi=*.

Ralf