powerpc: Hugetlb for BookE

Enable hugepages on Freescale BookE processors.  This allows the kernel to
use huge TLB entries to map pages, which can greatly reduce the number of
TLB misses and the amount of TLB thrashing experienced by applications with
large memory footprints.  Care should be taken when using this on FSL
processors, as the number of large TLB entries supported by the core is low
(16-64) on current processors.

The supported set of hugepage sizes include 4m, 16m, 64m, 256m, and 1g.
Page sizes larger than the max zone size are called "gigantic" pages and
must be allocated on the command line (and cannot be deallocated).

This is currently only fully implemented for Freescale 32-bit BookE
processors, but there is some infrastructure in the code for
64-bit BooKE.

Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index e06e39589a0..a85990c886e 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -69,6 +69,7 @@ config PPC_BOOK3S_64
         bool "Server processors"
         select PPC_FPU
         select PPC_HAVE_PMU_SUPPORT
+        select SYS_SUPPORTS_HUGETLBFS
 
 config PPC_BOOK3E_64
         bool "Embedded processors"
@@ -173,6 +174,7 @@ config BOOKE
 config FSL_BOOKE
         bool
         depends on (E200 || E500) && PPC32
+        select SYS_SUPPORTS_HUGETLBFS if PHYS_64BIT
         default y
 
 # this is for common code between PPC32 & PPC64 FSL BOOKE
@@ -296,7 +298,7 @@ config PPC_BOOK3E_MMU
 
 config PPC_MM_SLICES
         bool
-        default y if HUGETLB_PAGE || (PPC_STD_MMU_64 && PPC_64K_PAGES)
+        default y if (PPC64 && HUGETLB_PAGE) || (PPC_STD_MMU_64 && PPC_64K_PAGES)
         default n
 
 config VIRT_CPU_ACCOUNTING