MVME5500 broken with gcc-4.0.2

[Joel Sherrill <joel@OARcorp.com>]

Till Straumann wrote:
> WARNING:
> 
> rtems/gcc (implicitely) uses -maltivec on all 74xx CPUS and
> the MVME5500 calls for -mcpu=7450.
> 
> Unfortunately, with -maltivec, gcc uses vector registers for
> some optimizations.

What are those optimizations?  Are they integer or floating point
related?

The answer determines the proper thing for RTEMS to do.

> --> until proper altivec support is implemented in RTEMS random
>     *data corruption* must be expected.

I can't tell from the gcc code when Altivec registers might get used
so my first guess would be that we would need _CPU_Context_Switch to
switch the Altivec registers and the contexts to include Altivec registers.


> Workaround:
> 
> make/custom/mvme5500: use -mcpu=750
> 
> -- Till