From: Dave Hansen <haveblue@us.ibm.com>

I was compiling for my plain 'ol PC, and was getting unresolved symbols
for get_memcfg_from_srat() and get_zholes_size().  The CONFIG_NUMA
definition right now allows it to be turned on for plain old X86_PC. 
Does anyone know why this is? 

depends on SMP && HIGHMEM64G &&
          (X86_PC || X86_NUMAQ || X86_GENERICARCH ||
                  (X86_SUMMIT && ACPI && !ACPI_HT_ONLY))

In any case, the summit code incorrectly assumes in at least 2 places
that NUMA && !NUMAQ means summit.  Someone was evidently trying to cover
the generic subarch case, but that's already taken care of by the lovely
config system and CONFIG_ACPI_SRAT.  This patch fixes those assumptions
and adds a nice little warning for people that try to #include srat.h
without having srat support turned on.