Let impossible CPUs point to reference per cpu data

Hack for 2.6.16. In 2.6.17 all code that uses NR_CPUs should
be audited and changed to only touch possible CPUs.

Don't mark the reference per cpu data init data (so it stays
around after boot) and point all impossible CPUs to it. This way
they reference some valid - although shared memory. Usually
this is only initialization like INIT_LIST_HEADs and there
won't be races because these CPUs never run. Still somewhat hackish.

Signed-off-by: Andi Kleen <ak@suse.de>

Index: linux/arch/x86_64/kernel/setup64.c
===================================================================
--- linux.orig/arch/x86_64/kernel/setup64.c
+++ linux/arch/x86_64/kernel/setup64.c
@@ -99,8 +99,15 @@ void __init setup_per_cpu_areas(void)
 		size = PERCPU_ENOUGH_ROOM;
 #endif
 
-	for_each_cpu_mask (i, cpu_possible_map) {
+	for (i = 0; i < NR_CPUS; i++) { 
 		char *ptr;
+		
+		/* Later set this to a unmapped area, but first 
+		   need to clean up NR_CPUS usage everywhere */
+		if (!cpu_possible(i)) {	
+			/* Point the the original reference data */
+			cpu_pda(i)->data_offset = 0;
+		}
 
 		if (!NODE_DATA(cpu_to_node(i))) {
 			printk("cpu with no node %d, num_online_nodes %d\n",
Index: linux/arch/x86_64/kernel/vmlinux.lds.S
===================================================================
--- linux.orig/arch/x86_64/kernel/vmlinux.lds.S
+++ linux/arch/x86_64/kernel/vmlinux.lds.S
@@ -172,13 +172,16 @@ SECTIONS
   . = ALIGN(4096);
   __initramfs_start = .;
   .init.ramfs : AT(ADDR(.init.ramfs) - LOAD_OFFSET) { *(.init.ramfs) }
-  __initramfs_end = .;	
+ /* temporary here to work around NR_CPUS. If you see this comment in 2.6.17+
+   complain */ 
+ __initramfs_end = .;	
+  . = ALIGN(4096);
+  __init_end = .;	
   . = ALIGN(32);
   __per_cpu_start = .;
   .data.percpu  : AT(ADDR(.data.percpu) - LOAD_OFFSET) { *(.data.percpu) }
   __per_cpu_end = .;
-  . = ALIGN(4096);
-  __init_end = .;
+  /* __init_end / ALIGN(4096) should be here */
 
   . = ALIGN(4096);
   __nosave_begin = .;