- All the support macros which assume a linear mem_map[] have been
   wrapped in !CONFIG_DISCONTIGMEM.  pfn_to_page, page_to_pfn,
   page_to_phys, pmd_page, kern_addr_valid.

 - Move some initialsation macros into setup.h so they can be used in
   the i386 discontig.c (INITRD_START, INITRD_SIZE).

 - Alternate version of the bootmem allocator

 - add i386 discontig support and numaq support.