int __init build_node_maps (unsigned long start, unsigned long len, int node);
We allocate a struct bootmem_data for each piece of memory that we wish to treat as a virtually contiguous block (i.e. each node). Each such block must start on an IA64_GRANULE_SIZE boundary, so we round the address down if necessary. Any non-existent pages will simply be part of the virtual memmap. We also update min_low_pfn and max_low_pfn here as we receive memory ranges from the caller.