[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, 12 insertions, 8 deletions

diff --git a/include/asm-powerpc/thread_info.h b/include/asm-powerpc/thread_info.h
index ab17db79f69d..e525f49bd179 100644
--- a/include/asm-powerpc/thread_info.h
+++ b/include/asm-powerpc/thread_info.h
@@ -65,23 +65,27 @@ struct thread_info {
 
 /* thread information allocation */
 
-#ifdef CONFIG_DEBUG_STACK_USAGE
-#define THREAD_INFO_GFP         GFP_KERNEL | __GFP_ZERO
-#else
-#define THREAD_INFO_GFP         GFP_KERNEL
-#endif
-
 #if THREAD_SHIFT >= PAGE_SHIFT
 
 #define THREAD_ORDER    (THREAD_SHIFT - PAGE_SHIFT)
 
+#ifdef CONFIG_DEBUG_STACK_USAGE
 #define alloc_thread_info(tsk)  \
-        ((struct thread_info *)__get_free_pages(THREAD_INFO_GFP, THREAD_ORDER))
+        ((struct thread_info *)__get_free_pages(GFP_KERNEL | \
+                __GFP_ZERO, THREAD_ORDER))
+#else
+#define alloc_thread_info(tsk)  \
+        ((struct thread_info *)__get_free_pages(GFP_KERNEL, THREAD_ORDER))
+#endif
 #define free_thread_info(ti)    free_pages((unsigned long)ti, THREAD_ORDER)
 
 #else /* THREAD_SHIFT < PAGE_SHIFT */
 
-#define alloc_thread_info(tsk)  kmalloc(THREAD_SIZE, THREAD_INFO_GFP)
+#ifdef CONFIG_DEBUG_STACK_USAGE
+#define alloc_thread_info(tsk)  kzalloc(THREAD_SIZE, GFP_KERNEL)
+#else
+#define alloc_thread_info(tsk)  kmalloc(THREAD_SIZE, GFP_KERNEL)
+#endif
 #define free_thread_info(ti)    kfree(ti)
 
 #endif /* THREAD_SHIFT < PAGE_SHIFT */