We need to map in some memory areas >8MB just to find out how much
memory we have, and where it is. (the e820 table doesn't cut it on this
hardware)

This is only intended for remapping while the boot-time pagetables are
still in use.  It was a pain to get the 2-level pgtable.h functions, so
I just undef'd CONFIG_X86_PAE for my file.  It looks awfully hackish,
but it works well.

Some of my colleagues (Martin) would prefer to steal ptes from some
other source (just pick the last N from pg1), then replace them when the
remapping is done.  I don't really like this approach.  I prefer to know
exactly where I'm stealing them from, which is where boot_ioremap_area[]
comes in.

I would be amenable to making this dependent on some config option set
via CONFIG_X86_SUMMIT, to keep from bloating the normal kernel case
which doesn't use this code.
-- 
Dave Hansen
haveblue@us.ibm.com