From 0889eba5b38f66d7d892a167d88284daddd3d43b Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Tue, 16 Oct 2007 01:24:15 -0700 Subject: x86_64: SPARSEMEM_VMEMMAP 2M page size support x86_64 uses 2M page table entries to map its 1-1 kernel space. We also implement the virtual memmap using 2M page table entries. So there is no additional runtime overhead over FLATMEM, initialisation is slightly more complex. As FLATMEM still references memory to obtain the mem_map pointer and SPARSEMEM_VMEMMAP uses a compile time constant, SPARSEMEM_VMEMMAP should be superior. With this SPARSEMEM becomes the most efficient way of handling virt_to_page, pfn_to_page and friends for UP, SMP and NUMA on x86_64. [apw@shadowen.org: code resplit, style fixups] [apw@shadowen.org: vmemmap x86_64: ensure end of section memmap is initialised] Signed-off-by: Christoph Lameter Signed-off-by: Andy Whitcroft Acked-by: Mel Gorman Cc: Andi Kleen Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86_64/Kconfig | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86_64') diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig index cf013cb85ea..8c83dbe4c4d 100644 --- a/arch/x86_64/Kconfig +++ b/arch/x86_64/Kconfig @@ -409,6 +409,7 @@ config ARCH_DISCONTIGMEM_DEFAULT config ARCH_SPARSEMEM_ENABLE def_bool y depends on (NUMA || EXPERIMENTAL) + select SPARSEMEM_VMEMMAP_ENABLE config ARCH_MEMORY_PROBE def_bool y -- cgit v1.2.3-70-g09d2