[PATCH] i386: Add missing !X86_PAE dependincy to the 2G/2G split.

Only 1GB-aligned kernel/user splits are now handled for PAE. The
2GB/2GB split attempts to avoid aliasing vmallocspace with the 1:1
mapping for physical memory by using an actual split of 1.875/2.125
to accommodate 128MB of vmallocspace out of what would otherwise
be a full 2GB for userspace. That attempt disturbs the alignment
required by PAE for 2GB/2GB splits, and furthermore does not provide
a 2GB/2GB split as advertised.

This patch resolves the issues here in two manners. The first is
by providing a true 2GB/2GB split in addition to the 1.875/2.125
split. The second is by renaming the 1.875/2.125 split to
CONFIG_VMSPLIT_2G_OPT analogously to CONFIG_VMSPLIT_3G_OPT, which
performs a similar manuever to avoid aliasing vmallocspace with
the 1:1 mapping for physical memory around the 3GB boundary. With
the 1.875/2.125 split properly-named, its config option is then
tagged as depending on !HIGHMEM to express the PAE implementation's
current inability to deal with such unaligned splits.

This patch is essentially a combination of two patches, one written
by Eric Biederman and the other by Eric Dumazet. If they could add
their Signed-off-by: to this, I'd be much obliged.

Signed-off-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Mark Lord <lkml@rtr.ca>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Andi Kleen <ak@suse.de>

arch/i386/Kconfig

@@ -571,14 +571,18 @@ choice
 		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
+		bool "2G/2G user/kernel split (for full 2G low memory)"
 	config VMSPLIT_1G
 		bool "1G/3G user/kernel split"
 endchoice
 
 config PAGE_OFFSET
 	hex
 	default 0xB0000000 if VMSPLIT_3G_OPT
-	default 0x78000000 if VMSPLIT_2G
+	default 0x80000000 if VMSPLIT_2G
+	default 0x78000000 if VMSPLIT_2G_OPT
 	default 0x40000000 if VMSPLIT_1G
 	default 0xC0000000