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authorWilliam Lee Irwin III <wli@holomorphy.com>2007-07-21 17:11:13 +0200
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-21 18:37:12 -0700
commitc673f1a9d994de501b674b2bb6a48bd5e912afe0 (patch)
tree0657b02b263c24d91f4f6a82c841894bb17bcbb8 /arch/i386
parent075bcd1f9726b8a1caff86eda06f29f71fb21235 (diff)
i386: divorce CONFIG_X86_PAE from CONFIG_HIGHMEM64G
PAE is useful for more than supporting more than 4GB RAM. It supports expanded swapspace and NX executable protections. Some users may want NX or expanded swapspace support without the overhead or instability of highmem. For these reasons, the following patch divorces CONFIG_X86_PAE from CONFIG_HIGHMEM64G. Cc: Mark Lord <lkml@rtr.ca> Signed-off-by: William Irwin <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/i386')
-rw-r--r--arch/i386/Kconfig16
-rw-r--r--arch/i386/kernel/setup.c8
2 files changed, 15 insertions, 9 deletions
diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index 361aca8b3ec..0790bdf8c1f 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -548,6 +548,7 @@ config HIGHMEM4G
config HIGHMEM64G
bool "64GB"
depends on !M386 && !M486
+ select X86_PAE
help
Select this if you have a 32-bit processor and more than 4
gigabytes of physical RAM.
@@ -577,12 +578,12 @@ choice
config VMSPLIT_3G
bool "3G/1G user/kernel split"
config VMSPLIT_3G_OPT
- depends on !HIGHMEM
+ depends on !X86_PAE
bool "3G/1G user/kernel split (for full 1G low memory)"
config VMSPLIT_2G
bool "2G/2G user/kernel split"
config VMSPLIT_2G_OPT
- depends on !HIGHMEM
+ depends on !X86_PAE
bool "2G/2G user/kernel split (for full 2G low memory)"
config VMSPLIT_1G
bool "1G/3G user/kernel split"
@@ -602,10 +603,15 @@ config HIGHMEM
default y
config X86_PAE
- bool
- depends on HIGHMEM64G
- default y
+ bool "PAE (Physical Address Extension) Support"
+ default n
+ depends on !HIGHMEM4G
select RESOURCES_64BIT
+ help
+ PAE is required for NX support, and furthermore enables
+ larger swapspace support for non-overcommit purposes. It
+ has the cost of more pagetable lookup overhead, and also
+ consumes more pagetable space per process.
# Common NUMA Features
config NUMA
diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c
index 2986b48a823..d474cd639bc 100644
--- a/arch/i386/kernel/setup.c
+++ b/arch/i386/kernel/setup.c
@@ -273,18 +273,18 @@ unsigned long __init find_max_low_pfn(void)
printk(KERN_WARNING "Warning only %ldMB will be used.\n",
MAXMEM>>20);
if (max_pfn > MAX_NONPAE_PFN)
- printk(KERN_WARNING "Use a PAE enabled kernel.\n");
+ printk(KERN_WARNING "Use a HIGHMEM64G enabled kernel.\n");
else
printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
max_pfn = MAXMEM_PFN;
#else /* !CONFIG_HIGHMEM */
-#ifndef CONFIG_X86_PAE
+#ifndef CONFIG_HIGHMEM64G
if (max_pfn > MAX_NONPAE_PFN) {
max_pfn = MAX_NONPAE_PFN;
printk(KERN_WARNING "Warning only 4GB will be used.\n");
- printk(KERN_WARNING "Use a PAE enabled kernel.\n");
+ printk(KERN_WARNING "Use a HIGHMEM64G enabled kernel.\n");
}
-#endif /* !CONFIG_X86_PAE */
+#endif /* !CONFIG_HIGHMEM64G */
#endif /* !CONFIG_HIGHMEM */
} else {
if (highmem_pages == -1)