[RFC] Verification and debugging of memory initialisation

Boot initialisation has always been a bit of a mess with a number
of ugly points. While significant amounts of the initialisation
is architecture-independent, it trusts of the data received from the
architecture layer. This was a mistake in retrospect as it has resulted in
a number of difficult-to-diagnose bugs.

This patchset is an RFC to add some validation and tracing to memory
initialisation. It also introduces a few basic defencive measures and
depending on a boot parameter, will perform additional tests for errors
"that should never occur". I think this would have reduced debugging time
for some boot-related problems. The last part of the patchset is a similar
fix for the patch "[patch] mm: sparsemem memory_present() memory corruption"
that corrects a few more areas where similar errors were made.

I'm not looking to merge this as-is obviously but are there opinions on
whether this is a good idea in principal? Should it be done differently or
not at all?

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab