Attach is a patch that allows a i386 numa based system to boot without
memory in a node.  It deals with the assumption that all nodes have
memory.  
  
  In a summit based system (IBM x440/x445) is is possible to configure a
box with no memory is a node.  While this is not an ideal performance
setup it is a valid configuration for the box and the kernel should be
able to deal with it.  

 This "memory free node" must not be node 0.  Node 0 must still contain
memory (there are tons of hard coded 0's in the mm code so I am steering
around this for now).

  The assumption that all nodes have memory is not always true.  I have
introduced a simple node_has_online_mem functionality in the topology
code.  This check is based on 
node_start_pfn[nid] == node_end_pfn[nid] 
and as such the node_start/end_pfn must only contain physically present
memory.  

 I presented a patch a while ago that allowed non-present memory
reported from the srat to be ignored at the numa KVA level.  This patch
takes that a set further.  Ignore the memory above max_pfn altogether.  

  This main issues this patch address is fixing the numa_kva code as it
was built without this no-memory node in mind.

  It was tested with 2.6.11-rc4 on a 8-way x445 (summit) with no memory
in the 2nd node.  It supports both a physically empty and  SRAT based
hot-add empty zones just fine.  

Thanks,
  Keith Mannthey
  LTC xSeries