Commit:     c673f1a9d994de501b674b2bb6a48bd5e912afe0
Parent:     075bcd1f9726b8a1caff86eda06f29f71fb21235
Author:     William Lee Irwin III <[EMAIL PROTECTED]>
AuthorDate: Sat Jul 21 17:11:13 2007 +0200
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Sat Jul 21 18:37:12 2007 -0700

    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
    Cc: Mark Lord <[EMAIL PROTECTED]>
    Signed-off-by: William Irwin <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Andi Kleen <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
 arch/i386/Kconfig        |   16 +++++++++++-----
 arch/i386/kernel/setup.c |    8 ++++----
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index 361aca8..0790bdf 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
          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 2986b48..d474cd6 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",
                if (max_pfn > MAX_NONPAE_PFN)
-                       printk(KERN_WARNING "Use a PAE enabled kernel.\n");
+                       printk(KERN_WARNING "Use a HIGHMEM64G enabled 
                        printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
                max_pfn = MAXMEM_PFN;
 #else /* !CONFIG_HIGHMEM */
-#ifndef CONFIG_X86_PAE
                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 
-#endif /* !CONFIG_X86_PAE */
+#endif /* !CONFIG_HIGHMEM64G */
 #endif /* !CONFIG_HIGHMEM */
        } else {
                if (highmem_pages == -1)
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