[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, 4 insertions, 18 deletions

diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index b79a7820613..51b78694097 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -101,7 +101,6 @@ static int map_io_page(unsigned long ea, unsigned long pa, int flags)
 	pud_t *pudp;
 	pmd_t *pmdp;
 	pte_t *ptep;
-	unsigned long vsid;
 
 	if (mem_init_done) {
 		pgdp = pgd_offset_k(ea);
@@ -117,28 +116,15 @@ static int map_io_page(unsigned long ea, unsigned long pa, int flags)
 		set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT,
 							  __pgprot(flags)));
 	} else {
-		unsigned long va, vpn, hash, hpteg;
-
 		/*
 		 * If the mm subsystem is not fully up, we cannot create a
 		 * linux page table entry for this mapping.  Simply bolt an
 		 * entry in the hardware page table.
+		 *
 		 */
-		vsid = get_kernel_vsid(ea);
-		va = (vsid << 28) | (ea & 0xFFFFFFF);
-		vpn = va >> PAGE_SHIFT;
-
-		hash = hpt_hash(vpn, 0);
-
-		hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);
-
-		/* Panic if a pte grpup is full */
-		if (ppc_md.hpte_insert(hpteg, va, pa >> PAGE_SHIFT,
-				       HPTE_V_BOLTED,
-				       _PAGE_NO_CACHE|_PAGE_GUARDED|PP_RWXX)
-		    == -1) {
-			panic("map_io_page: could not insert mapping");
-		}
+		if (htab_bolt_mapping(ea, ea + PAGE_SIZE, pa, flags,
+				      mmu_virtual_psize))
+			panic("Can't map bolted IO mapping");
 	}
 	return 0;
 }