From: Dave Hansen The current VMSPLIT Kconfig option is disabled whenever highmem is on. This is a bit screwy because the people who need to change VMSPLIT the most tend to be the ones with highmem and constrained lowmem. So, remove the highmem dependency. But, re-include the dependency for the "full 1GB of lowmem" option. You can't have the full 1GB of lowmem and highmem because of the need for the vmalloc(), kmap(), etc... areas. I thought there would be at least a bit of tweaking to do to get it to work, but everything seems OK. Boot tested on a 4GB x86 machine, and a 12GB 3-node NUMA-Q: elm3b82:~# cat /proc/meminfo MemTotal: 3695412 kB MemFree: 3659540 kB ... LowTotal: 2909008 kB LowFree: 2892324 kB ... elm3b82:~# zgrep PAE /proc/config.gz CONFIG_X86_PAE=y larry:~# cat /proc/meminfo MemTotal: 11845900 kB MemFree: 11786748 kB ... LowTotal: 2855180 kB LowFree: 2830092 kB Signed-off-by: Dave Hansen Signed-off-by: Andrew Morton --- arch/i386/Kconfig | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff -puN arch/i386/Kconfig~x86-enable-vmsplit-for-highmem-kernels arch/i386/Kconfig --- a/arch/i386/Kconfig~x86-enable-vmsplit-for-highmem-kernels +++ a/arch/i386/Kconfig @@ -491,7 +491,7 @@ config HIGHMEM64G endchoice choice - depends on EXPERIMENTAL && !X86_PAE + depends on EXPERIMENTAL prompt "Memory split" if EMBEDDED default VMSPLIT_3G help @@ -513,6 +513,7 @@ choice config VMSPLIT_3G bool "3G/1G user/kernel split" config VMSPLIT_3G_OPT + depends on !HIGHMEM bool "3G/1G user/kernel split (for full 1G low memory)" config VMSPLIT_2G bool "2G/2G user/kernel split" _