[PATCH] create mm/Kconfig for arch-independent memory options

With sparsemem being introduced, we need a central place for new
memory-related .config options: mm/Kconfig.  This allows us to remove many
of the duplicated arch-specific options.

The new option, CONFIG_FLATMEM, is there to enable us to detangle NUMA and
DISCONTIGMEM.  This is a requirement for sparsemem because sparsemem uses
the NUMA code without the presence of DISCONTIGMEM.  The sparsemem patches
use CONFIG_FLATMEM in generic code, so this patch is a requirement before
applying them.

Almost all places that used to do '#ifndef CONFIG_DISCONTIGMEM' should use
'#ifdef CONFIG_FLATMEM' instead.
Signed-off-by: NAndy Whitcroft <apw@shadowen.org>
Signed-off-by: NDave Hansen <haveblue@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

mm/Kconfig

+choice
+	prompt "Memory model"
+	default FLATMEM
+	default SPARSEMEM if ARCH_SPARSEMEM_DEFAULT
+	default DISCONTIGMEM if ARCH_DISCONTIGMEM_DEFAULT
+
+config FLATMEM
+	bool "Flat Memory"
+	depends on !ARCH_DISCONTIGMEM_ENABLE || ARCH_FLATMEM_ENABLE
+	help
+	  This option allows you to change some of the ways that
+	  Linux manages its memory internally.  Most users will
+	  only have one option here: FLATMEM.  This is normal
+	  and a correct option.
+
+	  If unsure, choose this option over any other.
+
+config DISCONTIGMEM
+	bool "Discontigious Memory"
+	depends on ARCH_DISCONTIGMEM_ENABLE
+	help
+	  If unsure, choose "Flat Memory" over this option.
+
+endchoice
+