Index: 2006-01-05/arch/x86_64/kernel/setup64-xen.c
===================================================================
--- 2006-01-05.orig/arch/x86_64/kernel/setup64-xen.c	2006-01-05 13:14:04.000000000 +0100
+++ 2006-01-05/arch/x86_64/kernel/setup64-xen.c	2006-01-09 11:15:33.000000000 +0100
@@ -179,8 +179,6 @@ void pda_init(int cpu)
 	pda->irqcount = -1;
 	pda->kernelstack = 
 		(unsigned long)stack_thread_info() - PDA_STACKOFFSET + THREAD_SIZE; 
-	pda->active_mm = &init_mm;
-	pda->mmu_state = 0;
 
 	if (cpu == 0) {
 #ifdef CONFIG_XEN
Index: 2006-01-05/arch/x86_64/kernel/setup64.c
===================================================================
--- 2006-01-05.orig/arch/x86_64/kernel/setup64.c	2005-11-21 16:41:07.000000000 +0100
+++ 2006-01-05/arch/x86_64/kernel/setup64.c	2006-01-09 11:15:46.000000000 +0100
@@ -127,8 +127,10 @@ void pda_init(int cpu)
 	pda->irqcount = -1;
 	pda->kernelstack = 
 		(unsigned long)stack_thread_info() - PDA_STACKOFFSET + THREAD_SIZE; 
+#ifdef CONFIG_SMP
 	pda->active_mm = &init_mm;
 	pda->mmu_state = 0;
+#endif
 
 	if (cpu == 0) {
 		/* others are initialized in smpboot.c */
Index: 2006-01-05/include/asm-x86_64/pda.h
===================================================================
--- 2006-01-05.orig/include/asm-x86_64/pda.h	2005-11-21 16:42:15.000000000 +0100
+++ 2006-01-05/include/asm-x86_64/pda.h	2006-01-09 11:16:42.000000000 +0100
@@ -2,6 +2,7 @@
 #define X86_64_PDA_H
 
 #ifndef __ASSEMBLY__
+#include <linux/config.h>
 #include <linux/stddef.h>
 #include <linux/types.h>
 #include <linux/cache.h>
@@ -18,8 +19,10 @@ struct x8664_pda {
 	int nodenumber;		    /* number of current node */
 	unsigned int __softirq_pending;
 	unsigned int __nmi_count;	/* number of NMI on this CPUs */
+#if defined(CONFIG_SMP) && !defined(CONFIG_XEN)
 	struct mm_struct *active_mm;
-	int mmu_state;     
+	int mmu_state;
+#endif
 	unsigned apic_timer_irqs;
 } ____cacheline_aligned_in_smp;