[PATCH] ppc64: support 64k pages

Adds a new CONFIG_PPC_64K_PAGES which, when enabled, changes the kernel
base page size to 64K.  The resulting kernel still boots on any
hardware.  On current machines with 4K pages support only, the kernel
will maintain 16 "subpages" for each 64K page transparently.

Note that while real 64K capable HW has been tested, the current patch
will not enable it yet as such hardware is not released yet, and I'm
still verifying with the firmware architects the proper to get the
information from the newer hypervisors.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/arch/powerpc/mm/ppc_mmu_32.c b/arch/powerpc/mm/ppc_mmu_32.c
index cef9e83cc7e9..d137abd241ff 100644
--- a/arch/powerpc/mm/ppc_mmu_32.c
+++ b/arch/powerpc/mm/ppc_mmu_32.c
@@ -179,6 +179,21 @@ void __init setbat(int index, unsigned long virt, unsigned long phys,
 }
 
 /*
+ * Preload a translation in the hash table
+ */
+void hash_preload(struct mm_struct *mm, unsigned long ea,
+                  unsigned long access, unsigned long trap)
+{
+        pmd_t *pmd;
+
+        if (Hash == 0)
+                return;
+        pmd = pmd_offset(pgd_offset(vma->vm_mm, address), address);
+        if (!pmd_none(*pmd))
+                add_hash_page(vma->vm_mm->context, address, pmd_val(*pmd));
+}
+
+/*
  * Initialize the hash table and patch the instructions in hashtable.S.
  */
 void __init MMU_init_hw(void)