Move basic VIRTUAL_MEM_MAP code from IA64 to generic code

This patch genericizes the IA64 VIRTUAL_MEM_MAP support.

The VIRTUAL_MEM_MAP functions are simply a variation on
CONFIG_FLATMEM so use the existing FLATMEM definitions rather
than add to the multitude of existing definitions.

mem_map can now point to a static array or to a virtually
mapped array.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.18-mm3/include/asm-generic/memory_model.h
===================================================================
--- linux-2.6.18-mm3.orig/include/asm-generic/memory_model.h	2006-10-04 21:13:01.000000000 -0700
+++ linux-2.6.18-mm3/include/asm-generic/memory_model.h	2006-10-04 21:13:53.000000000 -0700
@@ -4,7 +4,7 @@
 #ifdef __KERNEL__
 #ifndef __ASSEMBLY__
 
-#if defined(CONFIG_FLATMEM)
+#if defined(CONFIG_FLATMEM) || defined(CONFIG_VIRTUAL_MEM_MAP)
 
 #ifndef ARCH_PFN_OFFSET
 #define ARCH_PFN_OFFSET		(0UL)
@@ -26,7 +26,7 @@
 /*
  * supports 3 memory models.
  */
-#if defined(CONFIG_FLATMEM)
+#if defined(CONFIG_FLATMEM) || defined(CONFIG_VIRTUAL_MEM_MAP)
 
 #define __pfn_to_page(pfn)	(mem_map + ((pfn) - ARCH_PFN_OFFSET))
 #define __page_to_pfn(page)	((unsigned long)((page) - mem_map) + \
Index: linux-2.6.18-mm3/include/asm-ia64/page.h
===================================================================
--- linux-2.6.18-mm3.orig/include/asm-ia64/page.h	2006-10-04 21:13:45.000000000 -0700
+++ linux-2.6.18-mm3/include/asm-ia64/page.h	2006-10-04 21:14:52.000000000 -0700
@@ -105,18 +105,7 @@
 # define ia64_pfn_valid(pfn) 1
 #endif
 
-#ifdef CONFIG_VIRTUAL_MEM_MAP
-extern struct page *mem_map;
-#ifdef CONFIG_DISCONTIGMEM
-# define page_to_pfn(page)	((unsigned long) (page - mem_map))
-# define pfn_to_page(pfn)	(mem_map + (pfn))
-#endif
-#endif
-
-#if defined(CONFIG_FLATMEM) || defined(CONFIG_SPARSEMEM)
-/* FLATMEM always configures mem_map */
 #include <asm-generic/memory_model.h>
-#endif
 
 #ifdef CONFIG_FLATMEM
 # define pfn_valid(pfn)		(((pfn) < max_mapnr) && ia64_pfn_valid(pfn))
Index: linux-2.6.18-mm3/include/linux/mmzone.h
===================================================================
--- linux-2.6.18-mm3.orig/include/linux/mmzone.h	2006-10-04 21:13:01.000000000 -0700
+++ linux-2.6.18-mm3/include/linux/mmzone.h	2006-10-04 21:13:53.000000000 -0700
@@ -338,7 +338,7 @@
 };
 #endif /* CONFIG_ARCH_POPULATES_NODE_MAP */
 
-#ifndef CONFIG_DISCONTIGMEM
+#if defined(CONFIG_VIRTUAL_MEM_MAP) || !defined(CONFIG_DISCONTIGMEM)
 /* The array of struct pages - for discontigmem use pgdat->lmem_map */
 extern struct page *mem_map;
 #endif