[PATCH]: expose FORCE_MAX_ZONEORDER on x86

[Marc Leeman]

Larger blocks of memory can be required for e.g. higher resolutions on
some capture card drivers; this patch just enables an already
available configuration option on x86 (it was already exposed on other
architectures).

The default is set to 11, as in
./include/linux/mmzone.h

[barco@nmgserver001 linux-3.0]$ find . -name Kconfig | xargs grep
FORCE_MAX_ZONEORDER
./arch/ia64/Kconfig:config FORCE_MAX_ZONEORDER
./arch/cris/Kconfig:config FORCE_MAX_ZONEORDER
./arch/arm/Kconfig:config FORCE_MAX_ZONEORDER
./arch/s390/Kconfig:config FORCE_MAX_ZONEORDER
./arch/mips/Kconfig:config FORCE_MAX_ZONEORDER
./arch/sh/mm/Kconfig:config FORCE_MAX_ZONEORDER
./arch/blackfin/Kconfig:config FORCE_MAX_ZONEORDER
./arch/powerpc/Kconfig:config FORCE_MAX_ZONEORDER



-- 
br, marc

The best approach for you requires two steps. The first step is
reading the Manual.
    Wolfgang Denk - u-boot mailing list
From 8ad64edbf92ac8e0253677bd3f9ad376ce3be7d1 Mon Sep 17 00:00:00 2001
From: Marc Leeman <marc.leeman@xxxxxxxxx>
Date: Wed, 26 Oct 2011 10:35:24 +0200
Subject: [PATCH] KConfig x86: enable FORCE_MAX_ZONEORDER

---
 arch/x86/Kconfig |   16 ++++++++++++++++
 1 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9a4a267..68a98e8 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1273,6 +1273,22 @@ config ILLEGAL_POINTER_VALUE
 
 source "mm/Kconfig"
 
+config FORCE_MAX_ZONEORDER
+	int "Maximum zone order" 
+	range 11 64
+	default "11"
+	help
+	  The kernel memory allocator divides physically contiguous memory
+	  blocks into "zones", where each zone is a power of two number of
+	  pages.  This option selects the largest power of two that the kernel
+	  keeps in the memory allocator.  If you need to allocate very large
+	  blocks of physically contiguous memory, then you may need to
+	  increase this value.
+
+	  This config option is actually maximum order plus one. For example,
+	  a value of 11 means that the largest free memory block is 2^10 pages.
+
+
 config HIGHPTE
 	bool "Allocate 3rd-level pagetables from highmem"
 	depends on HIGHMEM
-- 
1.7.2.5