[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, 19 insertions, 12 deletions

diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 6b52cce872be..b0994050024f 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -277,16 +277,21 @@ void __init early_setup(unsigned long dt_ptr)
         DBG("Found, Initializing memory management...\n");
 
         /*
-         * Initialize stab / SLB management
+         * Initialize the MMU Hash table and create the linear mapping
+         * of memory. Has to be done before stab/slb initialization as
+         * this is currently where the page size encoding is obtained
          */
-        if (!firmware_has_feature(FW_FEATURE_ISERIES))
-                stab_initialize(lpaca->stab_real);
+        htab_initialize();
 
         /*
-         * Initialize the MMU Hash table and create the linear mapping
-         * of memory
+         * Initialize stab / SLB management except on iSeries
          */
-        htab_initialize();
+        if (!firmware_has_feature(FW_FEATURE_ISERIES)) {
+                if (cpu_has_feature(CPU_FTR_SLB))
+                        slb_initialize();
+                else
+                        stab_initialize(lpaca->stab_real);
+        }
 
         DBG(" <- early_setup()\n");
 }
@@ -552,10 +557,12 @@ static void __init irqstack_early_init(void)
          * SLB misses on them.
          */
         for_each_cpu(i) {
-                softirq_ctx[i] = (struct thread_info *)__va(lmb_alloc_base(THREAD_SIZE,
-                                        THREAD_SIZE, 0x10000000));
-                hardirq_ctx[i] = (struct thread_info *)__va(lmb_alloc_base(THREAD_SIZE,
-                                        THREAD_SIZE, 0x10000000));
+                softirq_ctx[i] = (struct thread_info *)
+                        __va(lmb_alloc_base(THREAD_SIZE,
+                                            THREAD_SIZE, 0x10000000));
+                hardirq_ctx[i] = (struct thread_info *)
+                        __va(lmb_alloc_base(THREAD_SIZE,
+                                            THREAD_SIZE, 0x10000000));
         }
 }
 #else
@@ -583,8 +590,8 @@ static void __init emergency_stack_init(void)
         limit = min(0x10000000UL, lmb.rmo_size);
 
         for_each_cpu(i)
-                paca[i].emergency_sp = __va(lmb_alloc_base(PAGE_SIZE, 128,
-                                                limit)) + PAGE_SIZE;
+                paca[i].emergency_sp =
+                __va(lmb_alloc_base(HW_PAGE_SIZE, 128, limit)) + HW_PAGE_SIZE;
 }
 
 /*