• Negative #if's are harder to read as they don't tell exactly what arch something applies to. So change #ifndef to an explicit list of defines.
• Treate sparc64 and ia64 as 64-bit platforms, which means larger roots.
• sparc64 should halt back to the firmware, not reset.
• sparc64 doesn't need to play MS-DOS/BIOS partition crap games.

Reviewed by: jake