powerpc altivec support

[Till Straumann]

Hi.

I'm looking into ALTIVEC support for RTEMS along the lines of
lazy FP context switching. However, I'd like to hide this from
SCORE code for obvious reasons. OTOH, it seems also ugly
to switch the vector registers as a side effect of CPU_Context_switch().

Any suggestions?

Ralf: what needs to be done to get an altivec enabled toolchain and
newlib for the CPU variants that support it?

BTW: I see in gcc/config/rs-6000/t-rtems (gcc-3.2.3 / rtems-4.6) that
           "no-eabi" is passed to all PPC variants (MULTILIB_EXTRA_OPTS)
           -- this might be out of sync, as EABI is the default PPC abi for
           RTEMS [score/cpu/powerpc/rtems/score/ppc.h says:
/*
*  Default to the EABI used by current GNU tools
*/

#ifndef PPC_ABI
#define PPC_ABI PPC_ABI_EABI
#endif
]

            and I believe nobody ever defines this to something else.

-- Till