[IA64] Sparse virtual implementation

Equip IA64 sparsemem with a virtual memmap. This is similar to the existing
CONFIG_VMEMMAP functionality for discontig. It uses a page size mapping.

This is provided as a minimally intrusive solution. We split the
128TB VMALLOC area into two 64TB areas and use one for the virtual memmap.

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

Index: linux-2.6.21-rc5-mm2/arch/ia64/Kconfig
===================================================================
--- linux-2.6.21-rc5-mm2.orig/arch/ia64/Kconfig	2007-04-02 16:15:29.000000000 -0700
+++ linux-2.6.21-rc5-mm2/arch/ia64/Kconfig	2007-04-02 16:15:50.000000000 -0700
@@ -350,6 +350,10 @@ config ARCH_SPARSEMEM_ENABLE
 	def_bool y
 	depends on ARCH_DISCONTIGMEM_ENABLE
 
+config SPARSE_VIRTUAL
+	def_bool y
+	depends on ARCH_SPARSEMEM_ENABLE
+
 config ARCH_DISCONTIGMEM_DEFAULT
 	def_bool y if (IA64_SGI_SN2 || IA64_GENERIC || IA64_HP_ZX1 || IA64_HP_ZX1_SWIOTLB)
 	depends on ARCH_DISCONTIGMEM_ENABLE
Index: linux-2.6.21-rc5-mm2/include/asm-ia64/page.h
===================================================================
--- linux-2.6.21-rc5-mm2.orig/include/asm-ia64/page.h	2007-04-02 16:15:29.000000000 -0700
+++ linux-2.6.21-rc5-mm2/include/asm-ia64/page.h	2007-04-02 16:15:50.000000000 -0700
@@ -106,6 +106,9 @@ extern int ia64_pfn_valid (unsigned long
 # define ia64_pfn_valid(pfn) 1
 #endif
 
+#define vmemmap ((struct page *)(RGN_BASE(RGN_GATE) + \
+				(1UL << (4*PAGE_SHIFT - 10))))
+
 #ifdef CONFIG_VIRTUAL_MEM_MAP
 extern struct page *vmem_map;
 #ifdef CONFIG_DISCONTIGMEM
Index: linux-2.6.21-rc5-mm2/include/asm-ia64/pgtable.h
===================================================================
--- linux-2.6.21-rc5-mm2.orig/include/asm-ia64/pgtable.h	2007-04-02 16:15:29.000000000 -0700
+++ linux-2.6.21-rc5-mm2/include/asm-ia64/pgtable.h	2007-04-02 16:15:50.000000000 -0700
@@ -236,8 +236,13 @@ ia64_phys_addr_valid (unsigned long addr
 # define VMALLOC_END		vmalloc_end
   extern unsigned long vmalloc_end;
 #else
+#if defined(CONFIG_SPARSEMEM) && defined(CONFIG_SPARSE_VIRTUAL)
+/* SPARSE_VIRTUAL uses half of vmalloc... */
+# define VMALLOC_END		(RGN_BASE(RGN_GATE) + (1UL << (4*PAGE_SHIFT - 10)))
+#else
 # define VMALLOC_END		(RGN_BASE(RGN_GATE) + (1UL << (4*PAGE_SHIFT - 9)))
 #endif
+#endif
 
 /* fs/proc/kcore.c */
 #define	kc_vaddr_to_offset(v) ((v) - RGN_BASE(RGN_GATE))