diff -r 241ee47b0dc6 -r 0a27efea892b src/arch/alpha/interrupts.hh
--- a/src/arch/alpha/interrupts.hh	Fri Feb 24 11:52:49 2012 -0500
+++ b/src/arch/alpha/interrupts.hh	Fri Feb 24 18:34:02 2012 +0000
@@ -73,7 +73,7 @@
     }
 
     void
-    setCPU(BaseCPU * _cpu)
+    setCPU(BaseCPU * _cpu, bool defer_init)
     {
         cpu = _cpu;
     }
diff -r 241ee47b0dc6 -r 0a27efea892b src/arch/arm/interrupts.hh
--- a/src/arch/arm/interrupts.hh	Fri Feb 24 11:52:49 2012 -0500
+++ b/src/arch/arm/interrupts.hh	Fri Feb 24 18:34:02 2012 +0000
@@ -66,7 +66,7 @@
   public:
 
     void
-    setCPU(BaseCPU * _cpu)
+    setCPU(BaseCPU * _cpu, bool defer_init)
     {
         cpu = _cpu;
     }
diff -r 241ee47b0dc6 -r 0a27efea892b src/arch/mips/interrupts.hh
--- a/src/arch/mips/interrupts.hh	Fri Feb 24 11:52:49 2012 -0500
+++ b/src/arch/mips/interrupts.hh	Fri Feb 24 18:34:02 2012 +0000
@@ -63,7 +63,7 @@
     }
 
     void
-    setCPU(BaseCPU *_cpu)
+    setCPU(BaseCPU *_cpu, bool defer_init)
     {}
 
     //  post(int int_num, int index) is responsible
diff -r 241ee47b0dc6 -r 0a27efea892b src/arch/power/interrupts.hh
--- a/src/arch/power/interrupts.hh	Fri Feb 24 11:52:49 2012 -0500
+++ b/src/arch/power/interrupts.hh	Fri Feb 24 18:34:02 2012 +0000
@@ -57,7 +57,7 @@
     {}
 
     void
-    setCPU(BaseCPU * _cpu)
+    setCPU(BaseCPU * _cpu, bool defer_init)
     {
         cpu = _cpu;
     }
diff -r 241ee47b0dc6 -r 0a27efea892b src/arch/sparc/interrupts.hh
--- a/src/arch/sparc/interrupts.hh	Fri Feb 24 11:52:49 2012 -0500
+++ b/src/arch/sparc/interrupts.hh	Fri Feb 24 18:34:02 2012 +0000
@@ -54,7 +54,7 @@
   public:
 
     void
-    setCPU(BaseCPU * _cpu)
+    setCPU(BaseCPU * _cpu, bool defer_init)
     {
         cpu = _cpu;
     }
diff -r 241ee47b0dc6 -r 0a27efea892b src/arch/x86/interrupts.hh
--- a/src/arch/x86/interrupts.hh	Fri Feb 24 11:52:49 2012 -0500
+++ b/src/arch/x86/interrupts.hh	Fri Feb 24 18:34:02 2012 +0000
@@ -191,6 +191,9 @@
     // Port for receiving interrupts
     IntPort intSlavePort;
 
+    // Should we defer initialisation or not
+    bool deferInit;
+
   public:
 
     int getInitialApicId() { return initialApicId; }
@@ -200,7 +203,7 @@
      */
     typedef X86LocalApicParams Params;
 
-    void setCPU(BaseCPU * newCPU);
+    void setCPU(BaseCPU * newCPU, bool defer_init);
 
     void
     setClock(Tick newClock)
diff -r 241ee47b0dc6 -r 0a27efea892b src/arch/x86/interrupts.cc
--- a/src/arch/x86/interrupts.cc	Fri Feb 24 11:52:49 2012 -0500
+++ b/src/arch/x86/interrupts.cc	Fri Feb 24 18:34:02 2012 +0000
@@ -281,8 +281,12 @@
 
 
 void
-X86ISA::Interrupts::setCPU(BaseCPU * newCPU)
+X86ISA::Interrupts::setCPU(BaseCPU * newCPU, bool defer_init)
 {
+    // called both by the constructor of the CPU, and when switching a
+    // CPU in through takeOverFrom, and we need to know this to
+    // potentially defer initialisation (since it assumes our ports
+    // are connected)
     assert(newCPU);
     if (cpu != NULL && cpu->cpuId() != newCPU->cpuId()) {
         panic("Local APICs can't be moved between CPUs"
@@ -291,19 +295,27 @@
     cpu = newCPU;
     initialApicId = cpu->cpuId();
     regs[APIC_ID] = (initialApicId << 24);
+    // if we previously deferred initialisation, and now we should
+    // not, go ahead and do it
+    if (deferInit && !defer_init)
+        init();
+    deferInit = defer_init;
 }
 
 
 void
 X86ISA::Interrupts::init()
 {
-    //
-    // The local apic must register its address ranges on both its pio port
-    // via the basicpiodevice(piodevice) init() function and its int port
-    // that it inherited from IntDev.  Note IntDev is not a SimObject itself.
-    //
-    BasicPioDevice::init();
-    IntDev::init();
+    // if the CPU is to be switched in later it is not yet connected and
+    // we have to defer the initialisation
+    if (!deferInit) {
+        // The local apic must register its address ranges on both its
+        // pio port via the basicpiodevice(piodevice) init() function
+        // and its int port that it inherited from IntDev.  Note
+        // IntDev is not a SimObject itself.
+        BasicPioDevice::init();
+        IntDev::init();
+    }
 }
 
 
@@ -613,7 +625,7 @@
     pendingStartup(false), startupVector(0),
     startedUp(false), pendingUnmaskableInt(false),
     pendingIPIs(0), cpu(NULL),
-    intSlavePort(name() + ".int_slave", this, this, latency)
+    intSlavePort(name() + ".int_slave", this, this, latency), deferInit(true)
 {
     pioSize = PageBytes;
     memset(regs, 0, sizeof(regs));
diff -r 241ee47b0dc6 -r 0a27efea892b src/arch/x86/pagetable_walker.hh
--- a/src/arch/x86/pagetable_walker.hh	Fri Feb 24 11:52:49 2012 -0500
+++ b/src/arch/x86/pagetable_walker.hh	Fri Feb 24 18:34:02 2012 +0000
@@ -80,7 +80,6 @@
 
         friend class WalkerPort;
         WalkerPort port;
-        Port *getPort(const std::string &if_name, int idx = -1);
 
         // State to track each walk of the page table
         class WalkerState : public FastAlloc
@@ -168,6 +167,8 @@
         Fault startFunctional(ThreadContext * _tc, Addr &addr,
                 Addr &pageSize, BaseTLB::Mode mode);
 
+        Port *getPort(const std::string &if_name, int idx = -1);
+
       protected:
         // The TLB we're supposed to load.
         TLB * tlb;
diff -r 241ee47b0dc6 -r 0a27efea892b src/arch/x86/tlb.hh
--- a/src/arch/x86/tlb.hh	Fri Feb 24 11:52:49 2012 -0500
+++ b/src/arch/x86/tlb.hh	Fri Feb 24 18:34:02 2012 +0000
@@ -120,6 +120,9 @@
         // Checkpointing
         virtual void serialize(std::ostream &os);
         virtual void unserialize(Checkpoint *cp, const std::string &section);
+
+        // Get the port from the table walker and return it
+        virtual Port *getPort();
     };
 }
 
diff -r 241ee47b0dc6 -r 0a27efea892b src/arch/x86/tlb.cc
--- a/src/arch/x86/tlb.cc	Fri Feb 24 11:52:49 2012 -0500
+++ b/src/arch/x86/tlb.cc	Fri Feb 24 18:34:02 2012 +0000
@@ -421,6 +421,12 @@
 {
 }
 
+Port*
+TLB::getPort()
+{
+    return walker->getPort("port");
+}
+
 } // namespace X86ISA
 
 X86ISA::TLB *
diff -r 241ee47b0dc6 -r 0a27efea892b src/cpu/base.cc
--- a/src/cpu/base.cc	Fri Feb 24 11:52:49 2012 -0500
+++ b/src/cpu/base.cc	Fri Feb 24 18:34:02 2012 +0000
@@ -222,7 +222,9 @@
     // Check if CPU model has interrupts connected. The CheckerCPU
     // cannot take interrupts directly for example.
     if (interrupts)
-        interrupts->setCPU(this);
+        // let the interrupt device know if it should defer its
+        // initialisation based on our deferred registration
+        interrupts->setCPU(this, params()->defer_registration);
 
     if (FullSystem) {
         profileEvent = NULL;
@@ -455,7 +457,9 @@
     }
 
     interrupts = oldCPU->interrupts;
-    interrupts->setCPU(this);
+    // let the interrupt device know if it should initialise at this
+    // point based on the CPU's deferred registration
+    interrupts->setCPU(this, params()->defer_registration);
 
     if (FullSystem) {
         for (ThreadID i = 0; i < size; ++i)