Index: sys/amd64/amd64/mp_machdep.c
===================================================================
--- sys/amd64/amd64/mp_machdep.c
+++ sys/amd64/amd64/mp_machdep.c
@@ -58,7 +58,6 @@
 #include <vm/vm_param.h>
 #include <vm/pmap.h>
 #include <vm/vm_kern.h>
-#include <vm/vm_map.h>
 #include <vm/vm_extern.h>
 
 #include <x86/apicreg.h>
@@ -343,7 +342,6 @@
 	while (atomic_load_acq_int(&aps_ready) == 0)
 		ia32_pause();
 
-	pmap_activate_boot(vmspace_pmap(proc0.p_vmspace));
 	init_secondary_tail();
 }
 
Index: sys/i386/i386/pmap.c
===================================================================
--- sys/i386/i386/pmap.c
+++ sys/i386/i386/pmap.c
@@ -2000,9 +2000,9 @@
 #endif
 	pmap->pm_root.rt_root = 0;
 	CPU_ZERO(&pmap->pm_active);
-	PCPU_SET(curpmap, pmap);
 	TAILQ_INIT(&pmap->pm_pvchunk);
 	bzero(&pmap->pm_stats, sizeof pmap->pm_stats);
+	pmap_activate_boot(pmap);
 }
 
 /*
@@ -5804,6 +5804,20 @@
 	critical_exit();
 }
 
+void
+pmap_activate_boot(pmap_t pmap)
+{
+	u_int	cpuid;
+
+	cpuid = PCPU_GET(cpuid);
+#if defined(SMP)
+	CPU_SET_ATOMIC(cpuid, &pmap->pm_active);
+#else
+	CPU_SET(cpuid, &pmap->pm_active);
+#endif
+	PCPU_SET(curpmap, pmap);
+}
+
 void
 pmap_sync_icache(pmap_t pm, vm_offset_t va, vm_size_t sz)
 {
Index: sys/i386/i386/swtch.s
===================================================================
--- sys/i386/i386/swtch.s
+++ sys/i386/i386/swtch.s
@@ -74,16 +74,12 @@
  */
 ENTRY(cpu_throw)
 	movl	PCPU(CPUID), %esi
-	movl	4(%esp),%ecx			/* Old thread */
-	testl	%ecx,%ecx			/* no thread? */
-	jz	1f
 	/* release bit from old pm_active */
 	movl	PCPU(CURPMAP), %ebx
 #ifdef SMP
 	lock
 #endif
 	btrl	%esi, PM_ACTIVE(%ebx)		/* clear old */
-1:
 	movl	8(%esp),%ecx			/* New thread */
 	movl	TD_PCB(%ecx),%edx
 	/* set bit in new pm_active */
Index: sys/i386/include/pmap.h
===================================================================
--- sys/i386/include/pmap.h
+++ sys/i386/include/pmap.h
@@ -373,6 +373,7 @@
  * is called: pmap_kenter(), pmap_kextract(), pmap_kremove(), vtophys(), and
  * vtopte().
  */
+void	pmap_activate_boot(pmap_t pmap);
 void	pmap_bootstrap(vm_paddr_t);
 int	pmap_cache_bits(pmap_t, int mode, boolean_t is_pde);
 int	pmap_change_attr(vm_offset_t, vm_size_t, int);
Index: sys/x86/x86/mp_x86.c
===================================================================
--- sys/x86/x86/mp_x86.c
+++ sys/x86/x86/mp_x86.c
@@ -62,6 +62,7 @@
 #include <vm/pmap.h>
 #include <vm/vm_kern.h>
 #include <vm/vm_extern.h>
+#include <vm/vm_map.h>
 
 #include <x86/apicreg.h>
 #include <machine/clock.h>
@@ -967,6 +968,8 @@
 {
 	u_int cpuid;
 
+	pmap_activate_boot(vmspace_pmap(proc0.p_vmspace));
+
 	/*
 	 * On real hardware, switch to x2apic mode if possible.  Do it
 	 * after aps_ready was signalled, to avoid manipulating the