[PATCH 1/4] x86_64: Switch to SPARSE_VIRTUAL

Christoph Lameter
2007-04-01T07:10:37Z

x86_64 make SPARSE_VIRTUAL the default

x86_64 is using 2M page table entries to map its 1-1 kernel space.
We implement the virtual memmap also using 2M page table entries.
So there is no difference at all to FLATMEM. Both schemes require
a page table and a TLB.

Thus the SPARSEMEM becomes the most efficient way of handling
virt_to_page, pfn_to_page and friends for UP, SMP and NUMA.

So change the Kconfig for x86_64 to make SPARSE_VIRTUAL the
default and switch off all other memory models.

Oh. And PFN_TO_PAGE used to be out of line. Since it is now
so simple switch it back to inline.

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

Index: linux-2.6.21-rc5-mm2/arch/x86_64/Kconfig
===================================================================
--- linux-2.6.21-rc5-mm2.orig/arch/x86_64/Kconfig 2007-03-31 23:47:58.000000000 -0700
+++ linux-2.6.21-rc5-mm2/arch/x86_64/Kconfig 2007-03-31 23:48:41.000000000 -0700
@@ -380,25 +380,29 @@ config NUMA_EMU
number of nodes. This is only useful for debugging.

config ARCH_DISCONTIGMEM_ENABLE
- bool
- depends on NUMA
- default y
+ def_bool n

config ARCH_DISCONTIGMEM_DEFAULT
- def_bool y
- depends on NUMA
+ def_bool n

config ARCH_SPARSEMEM_ENABLE
def_bool y
- depends on (NUMA || EXPERIMENTAL)
+
+config SPARSEMEM_MANUAL
+ def_bool y
+
+config ARCH_SPARSE_VIRTUAL
+ def_bool y
+
+config SELECT_MEMORY_MODEL
+ def_bool n

config ARCH_MEMORY_PROBE
def_bool y
depends on MEMORY_HOTPLUG

config ARCH_FLATMEM_ENABLE
- def_bool y
- depends on !NUMA
+ def_bool n

source "mm/Kconfig"

@@ -411,8 +415,7 @@ config HAVE_ARCH_EARLY_PFN_TO_NID
depends on NUMA

config OUT_OF_LINE_PFN_TO_PAGE
- def_bool y
- depends on DISCONTIGMEM
+ def_bool n

config NR_CPUS
int "Maximum number of CPUs (2-255)"
Index: linux-2.6.21-rc5-mm2/include/asm-x86_64/page.h
===================================================================
--- linux-2.6.21-rc5-mm2.orig/include/asm-x86_64/page.h 2007-03-31 23:47:58.000000000 -0700
+++ linux-2.6.21-rc5-mm2/include/asm-x86_64/page.h 2007-03-31 23:48:41.000000000 -0700
@@ -135,6 +135,7 @@ typedef struct { unsigned long pgprot; }
VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)

#define __HAVE_ARCH_GATE_AREA 1
+#define vmemmap ((struct page *)0xffffe20000000000UL)

#include <asm-generic/memory_model.h>
#include <asm-generic/page.h>