On Mon, 2011-01-24 at 17:58 +0000, Russell King - ARM Linux wrote:

Wrong.  For flatmem, we have a pfn_valid() which is backed by doing a
one, two or maybe rarely three compare search of the memblocks.  Short
of having a bitmap of every page in the 4GB memory space, you can't
get more efficient than that.

Sweet.  So, we can just take the original patch that started this
conversation, add the requisite pfn_valid()s and pfn_to_page()s, and
skip the sparsemem #ifdefs.  Right?

-- Dave