CPU register extensions, was: Re: Multilib swamp

[Thomas Doerfler]

Hi all,

> >  
> >
> Brings me right back to the question I asked originally - how could we 
> best add hooks for
> altivec register context switching [ without introducing an ugly #ifdef 
> __PPC__ into cpukit]?
> 
> Ideas?

Just to throw a similar topic: the ColdFire architecture now has 
an optional "eMAC" unit for filtering instructions, which also 
involves an additional set of processor registers. This is quite 
a similar case as the AltiVec unit in PPC.

currently RTEMS can only distinguish between task with and 
without floating point (and FP registers). Wouldn't it be nice 
to expand this "one bit" decision to a multi bit decision for 
"CPU Expansion Units"? Would it be possible to move context 
switching code for these registers somehow into something 
similar to a RTEMS user extension?

wkr,
Thomas.


> 
> T.
> 
> >Ralf
> >
> >
> >  
> >
>