[ARM] add CONFIG_HIGHMEM option
Here it is... HIGHMEM for the ARM architecture. :-)
If you don't have enough ram for highmem pages to be allocated and still
want to test this, then the cmdline option "vmalloc=" can be used with
a value large enough to force the highmem threshold down.
Successfully tested on a Marvell DB-78x00-BP Development Board with
2 GB of RAM.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index dbfdf87..2b28786 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -915,6 +915,23 @@
default "2"
depends on NEED_MULTIPLE_NODES
+config HIGHMEM
+ bool "High Memory Support (EXPERIMENTAL)"
+ depends on MMU && EXPERIMENTAL
+ help
+ The address space of ARM processors is only 4 Gigabytes large
+ and it has to accommodate user address space, kernel address
+ space as well as some memory mapped IO. That means that, if you
+ have a large amount of physical memory and/or IO, not all of the
+ memory can be "permanently mapped" by the kernel. The physical
+ memory that is not permanently mapped is called "high memory".
+
+ Depending on the selected kernel/user memory split, minimum
+ vmalloc space and actual amount of RAM, you may not need this
+ option which should result in a slightly faster kernel.
+
+ If unsure, say n.
+
source "mm/Kconfig"
config LEDS