Steps towards setting up the infrastructure to allow the new CPU model to work in full system mode.

The major change is renaming the old ExecContext to CPUExecContext, and creating two new classes, ExecContext (an abstract class), and ProxyExecContext (a templated class that derives from ExecContext).

Code outside of the CPU continues to use ExecContext as normal (other than not being able to access variables within the XC).  The CPU uses the CPUExecContext, or however else it stores its own state.  It then creates a ProxyExecContext, templated on the class used to hold its state.  This proxy is passed to any code outside of the CPU that needs to access the XC.  This allows code outside of the CPU to use the ExecContext interface to access any state needed, without knowledge of how that state is laid out.

Note that these changes will not compile without the accompanying revision to automatically rename the shadow registers.

SConscript:
    Include new file, cpu_exec_context.cc.
arch/alpha/alpha_linux_process.cc:
arch/alpha/alpha_memory.cc:
arch/alpha/alpha_tru64_process.cc:
arch/alpha/arguments.cc:
arch/alpha/isa/decoder.isa:
arch/alpha/stacktrace.cc:
arch/alpha/vtophys.cc:
base/remote_gdb.cc:
cpu/intr_control.cc:
    Avoid directly accessing objects within the XC.
arch/alpha/ev5.cc:
    Avoid directly accessing objects within the XC.

    KernelStats have been moved to the BaseCPU instead of the XC.
arch/alpha/isa_traits.hh:
    Remove clearIprs().  It wasn't used very often and it did not work well with the proxy ExecContext.
cpu/base.cc:
    Place kernel stats within the BaseCPU instead of the ExecContext.

    For now comment out the profiling code sampling until its exact location is decided upon.
cpu/base.hh:
    Kernel stats are now in the BaseCPU instead of the ExecContext.
cpu/base_dyn_inst.cc:
cpu/base_dyn_inst.hh:
cpu/memtest/memtest.cc:
cpu/memtest/memtest.hh:
    Changes to support rename of old ExecContext to CPUExecContext.  See changeset for more details.
cpu/exetrace.cc:
    Remove unneeded include of exec_context.hh.
cpu/intr_control.hh:
cpu/o3/alpha_cpu_builder.cc:
    Remove unneeded include of exec_context.hh
cpu/o3/alpha_cpu.hh:
cpu/o3/alpha_cpu_impl.hh:
cpu/o3/cpu.cc:
cpu/o3/cpu.hh:
cpu/simple/cpu.cc:
cpu/simple/cpu.hh:
    Changes to support rename of old ExecContext to CPUExecContext.  See changeset for more details.

    Also avoid accessing anything directly from the XC.
cpu/pc_event.cc:
    Avoid accessing objects directly from the XC.
dev/tsunami_cchip.cc:
    Avoid accessing objects directly within the XC>
kern/freebsd/freebsd_system.cc:
kern/linux/linux_system.cc:
kern/linux/linux_threadinfo.hh:
kern/tru64/dump_mbuf.cc:
kern/tru64/tru64.hh:
kern/tru64/tru64_events.cc:
sim/syscall_emul.cc:
sim/syscall_emul.hh:
    Avoid accessing objects directly within the XC.
kern/kernel_stats.cc:
kern/kernel_stats.hh:
    Kernel stats no longer exist within the XC.
kern/system_events.cc:
    Avoid accessing objects directly within the XC.  Also kernel stats are now in the BaseCPU.
sim/process.cc:
sim/process.hh:
    Avoid accessing regs directly within an ExecContext.  Instead use a CPUExecContext to initialize the registers and copy them over.
cpu/cpu_exec_context.cc:
    Rename old ExecContext to CPUExecContext.  This is used by the old CPU models to store any necessary architectural state.  Also include the ProxyExecContext, which is used to access the CPUExecContext's state in code outside of the CPU.
cpu/cpu_exec_context.hh:
    Rename old ExecContext to CPUExecContext.  This is used by the old CPU models to store any necessary architectural state.  Also include the ProxyExecContext, which is used to access the CPUExecContext's state in code outside of the CPU.

    Remove kernel stats from the ExecContext.
sim/pseudo_inst.cc:
    Kernel stats now live within the CPU.

    Avoid accessing objects directly within the XC.

--HG--
rename : cpu/exec_context.cc => cpu/cpu_exec_context.cc
rename : cpu/exec_context.hh => cpu/cpu_exec_context.hh
extra : convert_revision : a75393a8945c80cca225b5e9d9c22a16609efb85

20 files changed, 1064 insertions, 570 deletions

diff --git a/cpu/base.cc b/cpu/base.cc
index 5a7ecf152..e2a4c214a 100644
--- a/cpu/base.cc
+++ b/cpu/base.cc
@@ -39,10 +39,16 @@
 #include "cpu/profile.hh"
 #include "cpu/sampler/sampler.hh"
 #include "sim/param.hh"
+#include "sim/process.hh"
 #include "sim/sim_events.hh"
+#include "sim/system.hh"
 
 #include "base/trace.hh"
 
+#if FULL_SYSTEM
+#include "kern/kernel_stats.hh"
+#endif
+
 using namespace std;
 
 vector<BaseCPU *> BaseCPU::cpuList;
@@ -147,7 +153,10 @@ BaseCPU::BaseCPU(Params *p)
     profileEvent = NULL;
     if (params->profile)
         profileEvent = new ProfileEvent(this, params->profile);
+
+    kernelStats = new Kernel::Statistics(system);
 #endif
+
 }
 
 BaseCPU::Params::Params()
@@ -165,6 +174,10 @@ BaseCPU::enableFunctionTrace()
 
 BaseCPU::~BaseCPU()
 {
+#if FULL_SYSTEM
+    if (kernelStats)
+        delete kernelStats;
+#endif
 }
 
 void
@@ -203,6 +216,11 @@ BaseCPU::regStats()
         }
     } else if (size == 1)
         execContexts[0]->regStats(name());
+
+#if FULL_SYSTEM
+    if (kernelStats)
+        kernelStats->regStats(name() + ".kern");
+#endif
 }
 
 
@@ -216,9 +234,9 @@ BaseCPU::registerExecContexts()
         if (id != -1)
             id += i;
 
-        xc->cpu_id = system->registerExecContext(xc, id);
+        xc->setCpuId(system->registerExecContext(xc, id));
 #else
-        xc->cpu_id = xc->process->registerExecContext(xc);
+        xc->setCpuId(xc->getProcessPtr()->registerExecContext(xc));
 #endif
     }
 }
@@ -240,12 +258,12 @@ BaseCPU::takeOverFrom(BaseCPU *oldCPU)
         ExecContext *oldXC = oldCPU->execContexts[i];
 
         newXC->takeOverFrom(oldXC);
-        assert(newXC->cpu_id == oldXC->cpu_id);
+        assert(newXC->readCpuId() == oldXC->readCpuId());
 #if FULL_SYSTEM
-        system->replaceExecContext(newXC, newXC->cpu_id);
+        system->replaceExecContext(newXC, newXC->readCpuId());
 #else
-        assert(newXC->process == oldXC->process);
-        newXC->process->replaceExecContext(newXC, newXC->cpu_id);
+        assert(newXC->getProcessPtr() == oldXC->getProcessPtr());
+        newXC->getProcessPtr()->replaceExecContext(newXC, newXC->readCpuId());
 #endif
     }
 
@@ -253,11 +271,11 @@ BaseCPU::takeOverFrom(BaseCPU *oldCPU)
     for (int i = 0; i < TheISA::NumInterruptLevels; ++i)
         interrupts[i] = oldCPU->interrupts[i];
     intstatus = oldCPU->intstatus;
-
+/*
     for (int i = 0; i < execContexts.size(); ++i)
         if (execContexts[i]->profile)
             execContexts[i]->profile->clear();
-
+*/
     if (profileEvent)
         profileEvent->schedule(curTick);
 #endif
@@ -272,11 +290,11 @@ BaseCPU::ProfileEvent::ProfileEvent(BaseCPU *_cpu, int _interval)
 void
 BaseCPU::ProfileEvent::process()
 {
-    for (int i = 0, size = cpu->execContexts.size(); i < size; ++i) {
+/*    for (int i = 0, size = cpu->execContexts.size(); i < size; ++i) {
         ExecContext *xc = cpu->execContexts[i];
         xc->profile->sample(xc->profileNode, xc->profilePC);
     }
-
+*/
     schedule(curTick + interval);
 }
 
@@ -327,6 +345,12 @@ BaseCPU::serialize(std::ostream &os)
 {
     SERIALIZE_ARRAY(interrupts, TheISA::NumInterruptLevels);
     SERIALIZE_SCALAR(intstatus);
+
+#if FULL_SYSTEM
+    if (kernelStats)
+        kernelStats->serialize(os);
+#endif
+
 }
 
 void
@@ -334,6 +358,11 @@ BaseCPU::unserialize(Checkpoint *cp, const std::string &section)
 {
     UNSERIALIZE_ARRAY(interrupts, TheISA::NumInterruptLevels);
     UNSERIALIZE_SCALAR(intstatus);
+
+#if FULL_SYSTEM
+    if (kernelStats)
+        kernelStats->unserialize(cp, section);
+#endif
 }
 
 #endif // FULL_SYSTEM
diff --git a/cpu/base.hh b/cpu/base.hh
index d5764d495..d9d5d2b88 100644
--- a/cpu/base.hh
+++ b/cpu/base.hh
@@ -40,6 +40,7 @@
 
 #if FULL_SYSTEM
 class System;
+namespace Kernel { class Statistics; }
 #endif
 
 class BranchPred;
@@ -234,6 +235,10 @@ class BaseCPU : public SimObject
   public:
     // Number of CPU cycles simulated
     Stats::Scalar<> numCycles;
+
+#if FULL_SYSTEM
+    Kernel::Statistics *kernelStats;
+#endif
 };
 
 #endif // __CPU_BASE_HH__
diff --git a/cpu/base_dyn_inst.cc b/cpu/base_dyn_inst.cc
index 86314bef1..a40b4a1dd 100644
--- a/cpu/base_dyn_inst.cc
+++ b/cpu/base_dyn_inst.cc
@@ -67,7 +67,7 @@ template <class Impl>
 BaseDynInst<Impl>::BaseDynInst(MachInst machInst, Addr inst_PC,
                                Addr pred_PC, InstSeqNum seq_num,
                                FullCPU *cpu)
-    : staticInst(machInst), traceData(NULL), cpu(cpu), xc(cpu->xcBase())
+    : staticInst(machInst), traceData(NULL), cpu(cpu), cpuXC(cpu->cpuXCBase())
 {
     seqNum = seq_num;
 
@@ -138,14 +138,14 @@ BaseDynInst<Impl>::prefetch(Addr addr, unsigned flags)
     // state.
 
     // Generate a MemReq so we can translate the effective address.
-    MemReqPtr req = new MemReq(addr, xc, 1, flags);
+    MemReqPtr req = new MemReq(addr, cpuXC->getProxy(), 1, flags);
     req->asid = asid;
 
     // Prefetches never cause faults.
     fault = NoFault;
 
     // note this is a local, not BaseDynInst::fault
-    Fault trans_fault = xc->translateDataReadReq(req);
+    Fault trans_fault = cpuXC->translateDataReadReq(req);
 
     if (trans_fault == NoFault && !(req->flags & UNCACHEABLE)) {
         // It's a valid address to cacheable space.  Record key MemReq
@@ -183,10 +183,10 @@ BaseDynInst<Impl>::writeHint(Addr addr, int size, unsigned flags)
     // will casue a TLB miss trap if necessary... not sure whether
     // that's the best thing to do or not.  We don't really need the
     // MemReq otherwise, since wh64 has no functional effect.
-    MemReqPtr req = new MemReq(addr, xc, size, flags);
+    MemReqPtr req = new MemReq(addr, cpuXC->getProxy(), size, flags);
     req->asid = asid;
 
-    fault = xc->translateDataWriteReq(req);
+    fault = cpuXC->translateDataWriteReq(req);
 
     if (fault == NoFault && !(req->flags & UNCACHEABLE)) {
         // Record key MemReq parameters so we can generate another one
@@ -211,18 +211,18 @@ template <class Impl>
 Fault
 BaseDynInst<Impl>::copySrcTranslate(Addr src)
 {
-    MemReqPtr req = new MemReq(src, xc, 64);
+    MemReqPtr req = new MemReq(src, cpuXC->getProxy(), 64);
     req->asid = asid;
 
     // translate to physical address
-    Fault fault = xc->translateDataReadReq(req);
+    Fault fault = cpuXC->translateDataReadReq(req);
 
     if (fault == NoFault) {
-        xc->copySrcAddr = src;
-        xc->copySrcPhysAddr = req->paddr;
+        cpuXC->copySrcAddr = src;
+        cpuXC->copySrcPhysAddr = req->paddr;
     } else {
-        xc->copySrcAddr = 0;
-        xc->copySrcPhysAddr = 0;
+        cpuXC->copySrcAddr = 0;
+        cpuXC->copySrcPhysAddr = 0;
     }
     return fault;
 }
@@ -235,18 +235,18 @@ Fault
 BaseDynInst<Impl>::copy(Addr dest)
 {
     uint8_t data[64];
-    FunctionalMemory *mem = xc->mem;
-    assert(xc->copySrcPhysAddr || xc->misspeculating());
-    MemReqPtr req = new MemReq(dest, xc, 64);
+    FunctionalMemory *mem = cpuXC->mem;
+    assert(cpuXC->copySrcPhysAddr || cpuXC->misspeculating());
+    MemReqPtr req = new MemReq(dest, cpuXC->getProxy(), 64);
     req->asid = asid;
 
     // translate to physical address
-    Fault fault = xc->translateDataWriteReq(req);
+    Fault fault = cpuXC->translateDataWriteReq(req);
 
     if (fault == NoFault) {
         Addr dest_addr = req->paddr;
         // Need to read straight from memory since we have more than 8 bytes.
-        req->paddr = xc->copySrcPhysAddr;
+        req->paddr = cpuXC->copySrcPhysAddr;
         mem->read(req, data);
         req->paddr = dest_addr;
         mem->write(req, data);
diff --git a/cpu/base_dyn_inst.hh b/cpu/base_dyn_inst.hh
index e94c44151..3a7852f79 100644
--- a/cpu/base_dyn_inst.hh
+++ b/cpu/base_dyn_inst.hh
@@ -145,7 +145,7 @@ class BaseDynInst : public FastAlloc, public RefCounted
     FullCPU *cpu;
 
     /** Pointer to the exec context.  Will not exist in the final version. */
-    ExecContext *xc;
+    CPUExecContext *cpuXC;
 
     /** The kind of fault this instruction has generated. */
     Fault fault;
@@ -406,7 +406,7 @@ class BaseDynInst : public FastAlloc, public RefCounted
     /** Returns the exec context.
      *  @todo: Remove this once the ExecContext is no longer used.
      */
-    ExecContext *xcBase() { return xc; }
+    ExecContext *xcBase() { return cpuXC->getProxy(); }
 
   private:
     /** Instruction effective address.
@@ -444,7 +444,7 @@ template<class T>
 inline Fault
 BaseDynInst<Impl>::read(Addr addr, T &data, unsigned flags)
 {
-    MemReqPtr req = new MemReq(addr, xc, sizeof(T), flags);
+    MemReqPtr req = new MemReq(addr, cpuXC->getProxy(), sizeof(T), flags);
     req->asid = asid;
 
     fault = cpu->translateDataReadReq(req);
@@ -492,7 +492,7 @@ BaseDynInst<Impl>::write(T data, Addr addr, unsigned flags, uint64_t *res)
         traceData->setData(data);
     }
 
-    MemReqPtr req = new MemReq(addr, xc, sizeof(T), flags);
+    MemReqPtr req = new MemReq(addr, cpuXC->getProxy(), sizeof(T), flags);
 
     req->asid = asid;
 
diff --git a/cpu/exec_context.cc b/cpu/cpu_exec_context.cc
index 9bed3ba47..2fb3d5d53 100644
--- a/cpu/exec_context.cc
+++ b/cpu/cpu_exec_context.cc
@@ -29,6 +29,7 @@
 #include <string>
 
 #include "cpu/base.hh"
+#include "cpu/cpu_exec_context.hh"
 #include "cpu/exec_context.hh"
 
 #if FULL_SYSTEM
@@ -49,23 +50,23 @@ using namespace std;
 
 // constructor
 #if FULL_SYSTEM
-ExecContext::ExecContext(BaseCPU *_cpu, int _thread_num, System *_sys,
+CPUExecContext::CPUExecContext(BaseCPU *_cpu, int _thread_num, System *_sys,
                          AlphaITB *_itb, AlphaDTB *_dtb,
                          FunctionalMemory *_mem)
     : _status(ExecContext::Unallocated), cpu(_cpu), thread_num(_thread_num),
       cpu_id(-1), mem(_mem), itb(_itb), dtb(_dtb), system(_sys),
-      memctrl(_sys->memctrl), physmem(_sys->physmem),
-      kernelBinning(system->kernelBinning), bin(kernelBinning->bin),
-      fnbin(kernelBinning->fnbin), profile(NULL),
+      memctrl(_sys->memctrl), physmem(_sys->physmem), profile(NULL),
       func_exe_inst(0), storeCondFailures(0)
 {
-    kernelStats = new Kernel::Statistics(this);
+    proxy = new ProxyExecContext<CPUExecContext>(this);
+
     memset(&regs, 0, sizeof(RegFile));
 
     if (cpu->params->profile) {
         profile = new FunctionProfile(system->kernelSymtab);
         Callback *cb =
-            new MakeCallback<ExecContext, &ExecContext::dumpFuncProfile>(this);
+            new MakeCallback<CPUExecContext,
+            &CPUExecContext::dumpFuncProfile>(this);
         registerExitCallback(cb);
     }
 
@@ -76,7 +77,7 @@ ExecContext::ExecContext(BaseCPU *_cpu, int _thread_num, System *_sys,
     profilePC = 3;
 }
 #else
-ExecContext::ExecContext(BaseCPU *_cpu, int _thread_num,
+CPUExecContext::CPUExecContext(BaseCPU *_cpu, int _thread_num,
                          Process *_process, int _asid)
     : _status(ExecContext::Unallocated),
       cpu(_cpu), thread_num(_thread_num), cpu_id(-1),
@@ -84,36 +85,46 @@ ExecContext::ExecContext(BaseCPU *_cpu, int _thread_num,
       func_exe_inst(0), storeCondFailures(0)
 {
     memset(&regs, 0, sizeof(RegFile));
+    proxy = new ProxyExecContext<CPUExecContext>(this);
 }
 
-ExecContext::ExecContext(BaseCPU *_cpu, int _thread_num,
+CPUExecContext::CPUExecContext(BaseCPU *_cpu, int _thread_num,
                          FunctionalMemory *_mem, int _asid)
     : cpu(_cpu), thread_num(_thread_num), process(0), mem(_mem), asid(_asid),
       func_exe_inst(0), storeCondFailures(0)
 {
     memset(&regs, 0, sizeof(RegFile));
+    proxy = new ProxyExecContext<CPUExecContext>(this);
 }
-#endif
 
-ExecContext::~ExecContext()
+CPUExecContext::CPUExecContext(RegFile *regFile)
+    : cpu(NULL), thread_num(-1), process(NULL), mem(NULL), asid(-1),
+      func_exe_inst(0), storeCondFailures(0)
 {
-#if FULL_SYSTEM
-    delete kernelStats;
+    regs = *regFile;
+    proxy = new ProxyExecContext<CPUExecContext>(this);
+}
+
 #endif
+
+CPUExecContext::~CPUExecContext()
+{
+    delete proxy;
 }
 
 #if FULL_SYSTEM
 void
-ExecContext::dumpFuncProfile()
+CPUExecContext::dumpFuncProfile()
 {
     std::ostream *os = simout.create(csprintf("profile.%s.dat", cpu->name()));
-    profile->dump(this, *os);
+    profile->dump(proxy, *os);
 }
 #endif
 
 void
-ExecContext::takeOverFrom(ExecContext *oldContext)
+CPUExecContext::takeOverFrom(ExecContext *oldContext)
 {
+/*
     // some things should already be set up
     assert(mem == oldContext->mem);
 #if FULL_SYSTEM
@@ -130,98 +141,115 @@ ExecContext::takeOverFrom(ExecContext *oldContext)
 
     storeCondFailures = 0;
 
-    oldContext->_status = ExecContext::Unallocated;
+    oldContext->_status = CPUExecContext::Unallocated;
+*/
 }
 
 void
-ExecContext::serialize(ostream &os)
+CPUExecContext::serialize(ostream &os)
 {
     SERIALIZE_ENUM(_status);
     regs.serialize(os);
     // thread_num and cpu_id are deterministic from the config
     SERIALIZE_SCALAR(func_exe_inst);
     SERIALIZE_SCALAR(inst);
-
-#if FULL_SYSTEM
-    kernelStats->serialize(os);
-#endif
 }
 
 
 void
-ExecContext::unserialize(Checkpoint *cp, const std::string &section)
+CPUExecContext::unserialize(Checkpoint *cp, const std::string &section)
 {
     UNSERIALIZE_ENUM(_status);
     regs.unserialize(cp, section);
     // thread_num and cpu_id are deterministic from the config
     UNSERIALIZE_SCALAR(func_exe_inst);
     UNSERIALIZE_SCALAR(inst);
-
-#if FULL_SYSTEM
-    kernelStats->unserialize(cp, section);
-#endif
 }
 
 
 void
-ExecContext::activate(int delay)
+CPUExecContext::activate(int delay)
 {
-    if (status() == Active)
+    if (status() == ExecContext::Active)
         return;
 
-    _status = Active;
+    _status = ExecContext::Active;
     cpu->activateContext(thread_num, delay);
 }
 
 void
-ExecContext::suspend()
+CPUExecContext::suspend()
 {
-    if (status() == Suspended)
+    if (status() == ExecContext::Suspended)
         return;
 
 #if FULL_SYSTEM
     // Don't change the status from active if there are pending interrupts
     if (cpu->check_interrupts()) {
-        assert(status() == Active);
+        assert(status() == ExecContext::Active);
         return;
     }
 #endif
 
-    _status = Suspended;
+    _status = ExecContext::Suspended;
     cpu->suspendContext(thread_num);
 }
 
 void
-ExecContext::deallocate()
+CPUExecContext::deallocate()
 {
-    if (status() == Unallocated)
+    if (status() == ExecContext::Unallocated)
         return;
 
-    _status = Unallocated;
+    _status = ExecContext::Unallocated;
     cpu->deallocateContext(thread_num);
 }
 
 void
-ExecContext::halt()
+CPUExecContext::halt()
 {
-    if (status() == Halted)
+    if (status() == ExecContext::Halted)
         return;
 
-    _status = Halted;
+    _status = ExecContext::Halted;
     cpu->haltContext(thread_num);
 }
 
 
 void
-ExecContext::regStats(const string &name)
+CPUExecContext::regStats(const string &name)
 {
-#if FULL_SYSTEM
-    kernelStats->regStats(name + ".kern");
-#endif
 }
 
 void
-ExecContext::trap(Fault fault)
+CPUExecContext::copyArchRegs(ExecContext *xc)
+{
+    // First loop through the integer registers.
+    for (int i = 0; i < AlphaISA::NumIntRegs; ++i) {
+        setIntReg(i, xc->readIntReg(i));
+    }
+
+    // Then loop through the floating point registers.
+    for (int i = 0; i < AlphaISA::NumFloatRegs; ++i) {
+        setFloatRegDouble(i, xc->readFloatRegDouble(i));
+        setFloatRegInt(i, xc->readFloatRegInt(i));
+    }
+
+    // Copy misc. registers
+    setMiscReg(AlphaISA::Fpcr_DepTag, xc->readMiscReg(AlphaISA::Fpcr_DepTag));
+    setMiscReg(AlphaISA::Uniq_DepTag, xc->readMiscReg(AlphaISA::Uniq_DepTag));
+    setMiscReg(AlphaISA::Lock_Flag_DepTag,
+               xc->readMiscReg(AlphaISA::Lock_Flag_DepTag));
+    setMiscReg(AlphaISA::Lock_Addr_DepTag,
+               xc->readMiscReg(AlphaISA::Lock_Addr_DepTag));
+
+    // Lastly copy PC/NPC
+    setPC(xc->readPC());
+    setNextPC(xc->readNextPC());
+}
+
+void
+CPUExecContext::trap(Fault fault)
 {
     //TheISA::trap(fault);    //One possible way to do it...
 
diff --git a/cpu/cpu_exec_context.hh b/cpu/cpu_exec_context.hh
new file mode 100644
index 000000000..1ae24582d
--- /dev/null
+++ b/cpu/cpu_exec_context.hh
@@ -0,0 +1,510 @@
+/*
+ * Copyright (c) 2001-2005 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __CPU_CPU_EXEC_CONTEXT_HH__
+#define __CPU_CPU_EXEC_CONTEXT_HH__
+
+#include "arch/isa_traits.hh"
+#include "config/full_system.hh"
+#include "cpu/exec_context.hh"
+#include "mem/functional/functional.hh"
+#include "mem/mem_req.hh"
+#include "sim/byteswap.hh"
+#include "sim/host.hh"
+#include "sim/serialize.hh"
+
+// forward declaration: see functional_memory.hh
+class FunctionalMemory;
+class PhysicalMemory;
+class BaseCPU;
+
+#if FULL_SYSTEM
+
+#include "sim/system.hh"
+#include "targetarch/alpha_memory.hh"
+
+class FunctionProfile;
+class ProfileNode;
+class MemoryController;
+
+#else // !FULL_SYSTEM
+
+#include "sim/process.hh"
+
+#endif // FULL_SYSTEM
+
+//
+// The CPUExecContext object represents a functional context for
+// instruction execution.  It incorporates everything required for
+// architecture-level functional simulation of a single thread.
+//
+
+class CPUExecContext
+{
+  protected:
+    typedef TheISA::RegFile RegFile;
+    typedef TheISA::MachInst MachInst;
+    typedef TheISA::MiscRegFile MiscRegFile;
+    typedef TheISA::MiscReg MiscReg;
+  public:
+    typedef ExecContext::Status Status;
+
+  private:
+    Status _status;
+
+  public:
+    Status status() const { return _status; }
+
+    void setStatus(Status newStatus) { _status = newStatus; }
+
+    /// Set the status to Active.  Optional delay indicates number of
+    /// cycles to wait before beginning execution.
+    void activate(int delay = 1);
+
+    /// Set the status to Suspended.
+    void suspend();
+
+    /// Set the status to Unallocated.
+    void deallocate();
+
+    /// Set the status to Halted.
+    void halt();
+
+  protected:
+    RegFile regs;	// correct-path register context
+
+  public:
+    // pointer to CPU associated with this context
+    BaseCPU *cpu;
+
+    ProxyExecContext<CPUExecContext> *proxy;
+
+    // Current instruction
+    MachInst inst;
+
+    // Index of hardware thread context on the CPU that this represents.
+    int thread_num;
+
+    // ID of this context w.r.t. the System or Process object to which
+    // it belongs.  For full-system mode, this is the system CPU ID.
+    int cpu_id;
+
+#if FULL_SYSTEM
+    FunctionalMemory *mem;
+    AlphaITB *itb;
+    AlphaDTB *dtb;
+    System *system;
+
+    // the following two fields are redundant, since we can always
+    // look them up through the system pointer, but we'll leave them
+    // here for now for convenience
+    MemoryController *memctrl;
+    PhysicalMemory *physmem;
+
+    FunctionProfile *profile;
+    ProfileNode *profileNode;
+    Addr profilePC;
+    void dumpFuncProfile();
+
+#else
+    Process *process;
+
+    FunctionalMemory *mem;	// functional storage for process address space
+
+    // Address space ID.  Note that this is used for TIMING cache
+    // simulation only; all functional memory accesses should use
+    // one of the FunctionalMemory pointers above.
+    short asid;
+
+#endif
+
+    /**
+     * Temporary storage to pass the source address from copy_load to
+     * copy_store.
+     * @todo Remove this temporary when we have a better way to do it.
+     */
+    Addr copySrcAddr;
+    /**
+     * Temp storage for the physical source address of a copy.
+     * @todo Remove this temporary when we have a better way to do it.
+     */
+    Addr copySrcPhysAddr;
+
+
+    /*
+     * number of executed instructions, for matching with syscall trace
+     * points in EIO files.
+     */
+    Counter func_exe_inst;
+
+    //
+    // Count failed store conditionals so we can warn of apparent
+    // application deadlock situations.
+    unsigned storeCondFailures;
+
+    // constructor: initialize context from given process structure
+#if FULL_SYSTEM
+    CPUExecContext(BaseCPU *_cpu, int _thread_num, System *_system,
+                   AlphaITB *_itb, AlphaDTB *_dtb, FunctionalMemory *_dem);
+#else
+    CPUExecContext(BaseCPU *_cpu, int _thread_num, Process *_process, int _asid);
+    CPUExecContext(BaseCPU *_cpu, int _thread_num, FunctionalMemory *_mem,
+                   int _asid);
+    // Constructor to use XC to pass reg file around.  Not used for anything
+    // else.
+    CPUExecContext(RegFile *regFile);
+#endif
+    virtual ~CPUExecContext();
+
+    virtual void takeOverFrom(ExecContext *oldContext);
+
+    void regStats(const std::string &name);
+
+    void serialize(std::ostream &os);
+    void unserialize(Checkpoint *cp, const std::string &section);
+
+    BaseCPU *getCpuPtr() { return cpu; }
+
+    ExecContext *getProxy() { return proxy; }
+
+    int getThreadNum() { return thread_num; }
+
+#if FULL_SYSTEM
+    System *getSystemPtr() { return system; }
+
+    PhysicalMemory *getPhysMemPtr() { return physmem; }
+
+    AlphaITB *getITBPtr() { return itb; }
+
+    AlphaDTB *getDTBPtr() { return dtb; }
+
+    bool validInstAddr(Addr addr) { return true; }
+    bool validDataAddr(Addr addr) { return true; }
+    int getInstAsid() { return regs.instAsid(); }
+    int getDataAsid() { return regs.dataAsid(); }
+
+    Fault translateInstReq(MemReqPtr &req)
+    {
+        return itb->translate(req);
+    }
+
+    Fault translateDataReadReq(MemReqPtr &req)
+    {
+        return dtb->translate(req, false);
+    }
+
+    Fault translateDataWriteReq(MemReqPtr &req)
+    {
+        return dtb->translate(req, true);
+    }
+
+#else
+    Process *getProcessPtr() { return process; }
+
+    bool validInstAddr(Addr addr)
+    { return process->validInstAddr(addr); }
+
+    bool validDataAddr(Addr addr)
+    { return process->validDataAddr(addr); }
+
+    int getInstAsid() { return asid; }
+    int getDataAsid() { return asid; }
+
+    Fault dummyTranslation(MemReqPtr &req)
+    {
+#if 0
+        assert((req->vaddr >> 48 & 0xffff) == 0);
+#endif
+
+        // put the asid in the upper 16 bits of the paddr
+        req->paddr = req->vaddr & ~((Addr)0xffff << sizeof(Addr) * 8 - 16);
+        req->paddr = req->paddr | (Addr)req->asid << sizeof(Addr) * 8 - 16;
+        return NoFault;
+    }
+    Fault translateInstReq(MemReqPtr &req)
+    {
+        return dummyTranslation(req);
+    }
+    Fault translateDataReadReq(MemReqPtr &req)
+    {
+        return dummyTranslation(req);
+    }
+    Fault translateDataWriteReq(MemReqPtr &req)
+    {
+        return dummyTranslation(req);
+    }
+
+#endif
+
+    template <class T>
+    Fault read(MemReqPtr &req, T &data)
+    {
+#if FULL_SYSTEM && defined(TARGET_ALPHA)
+        if (req->flags & LOCKED) {
+            req->xc->setMiscReg(TheISA::Lock_Addr_DepTag, req->paddr);
+            req->xc->setMiscReg(TheISA::Lock_Flag_DepTag, true);
+        }
+#endif
+
+        Fault error;
+        error = mem->read(req, data);
+        data = LittleEndianGuest::gtoh(data);
+        return error;
+    }
+
+    template <class T>
+    Fault write(MemReqPtr &req, T &data)
+    {
+#if FULL_SYSTEM && defined(TARGET_ALPHA)
+        ExecContext *xc;
+
+        // If this is a store conditional, act appropriately
+        if (req->flags & LOCKED) {
+            xc = req->xc;
+
+            if (req->flags & UNCACHEABLE) {
+                // Don't update result register (see stq_c in isa_desc)
+                req->result = 2;
+                xc->setStCondFailures(0);//Needed? [RGD]
+            } else {
+                bool lock_flag = xc->readMiscReg(TheISA::Lock_Flag_DepTag);
+                Addr lock_addr = xc->readMiscReg(TheISA::Lock_Addr_DepTag);
+                req->result = lock_flag;
+                if (!lock_flag ||
+                    ((lock_addr & ~0xf) != (req->paddr & ~0xf))) {
+                    xc->setMiscReg(TheISA::Lock_Flag_DepTag, false);
+                    xc->setStCondFailures(xc->readStCondFailures() + 1);
+                    if (((xc->readStCondFailures()) % 100000) == 0) {
+                        std::cerr << "Warning: "
+                                  << xc->readStCondFailures()
+                                  << " consecutive store conditional failures "
+                                  << "on cpu " << req->xc->readCpuId()
+                                  << std::endl;
+                    }
+                    return NoFault;
+                }
+                else xc->setStCondFailures(0);
+            }
+        }
+
+        // Need to clear any locked flags on other proccessors for
+        // this address.  Only do this for succsful Store Conditionals
+        // and all other stores (WH64?).  Unsuccessful Store
+        // Conditionals would have returned above, and wouldn't fall
+        // through.
+        for (int i = 0; i < system->execContexts.size(); i++){
+            xc = system->execContexts[i];
+            if ((xc->readMiscReg(TheISA::Lock_Addr_DepTag) & ~0xf) ==
+                (req->paddr & ~0xf)) {
+                xc->setMiscReg(TheISA::Lock_Flag_DepTag, false);
+            }
+        }
+
+#endif
+        return mem->write(req, (T)LittleEndianGuest::htog(data));
+    }
+
+    virtual bool misspeculating();
+
+
+    MachInst getInst() { return inst; }
+
+    void setInst(MachInst new_inst)
+    {
+        inst = new_inst;
+    }
+
+    Fault instRead(MemReqPtr &req)
+    {
+        return mem->read(req, inst);
+    }
+
+    void setCpuId(int id) { cpu_id = id; }
+
+    int readCpuId() { return cpu_id; }
+
+    FunctionalMemory *getMemPtr() { return mem; }
+
+    void copyArchRegs(ExecContext *xc);
+
+    //
+    // New accessors for new decoder.
+    //
+    uint64_t readIntReg(int reg_idx)
+    {
+        return regs.intRegFile[reg_idx];
+    }
+
+    float readFloatRegSingle(int reg_idx)
+    {
+        return (float)regs.floatRegFile.d[reg_idx];
+    }
+
+    double readFloatRegDouble(int reg_idx)
+    {
+        return regs.floatRegFile.d[reg_idx];
+    }
+
+    uint64_t readFloatRegInt(int reg_idx)
+    {
+        return regs.floatRegFile.q[reg_idx];
+    }
+
+    void setIntReg(int reg_idx, uint64_t val)
+    {
+        regs.intRegFile[reg_idx] = val;
+    }
+
+    void setFloatRegSingle(int reg_idx, float val)
+    {
+        regs.floatRegFile.d[reg_idx] = (double)val;
+    }
+
+    void setFloatRegDouble(int reg_idx, double val)
+    {
+        regs.floatRegFile.d[reg_idx] = val;
+    }
+
+    void setFloatRegInt(int reg_idx, uint64_t val)
+    {
+        regs.floatRegFile.q[reg_idx] = val;
+    }
+
+    uint64_t readPC()
+    {
+        return regs.pc;
+    }
+
+    void setPC(uint64_t val)
+    {
+        regs.pc = val;
+    }
+
+    uint64_t readNextPC()
+    {
+        return regs.npc;
+    }
+
+    void setNextPC(uint64_t val)
+    {
+        regs.npc = val;
+    }
+
+    MiscReg readMiscReg(int misc_reg)
+    {
+        return regs.miscRegs.readReg(misc_reg);
+    }
+
+    MiscReg readMiscRegWithEffect(int misc_reg, Fault &fault)
+    {
+        return regs.miscRegs.readRegWithEffect(misc_reg, fault, proxy);
+    }
+
+    Fault setMiscReg(int misc_reg, const MiscReg &val)
+    {
+        return regs.miscRegs.setReg(misc_reg, val);
+    }
+
+    Fault setMiscRegWithEffect(int misc_reg, const MiscReg &val)
+    {
+        return regs.miscRegs.setRegWithEffect(misc_reg, val, proxy);
+    }
+
+    unsigned readStCondFailures() { return storeCondFailures; }
+
+    void setStCondFailures(unsigned sc_failures)
+    { storeCondFailures = sc_failures; }
+
+    void clearArchRegs() { memset(&regs, 0, sizeof(regs)); }
+
+#if FULL_SYSTEM
+    int readIntrFlag() { return regs.intrflag; }
+    void setIntrFlag(int val) { regs.intrflag = val; }
+    Fault hwrei();
+    bool inPalMode() { return AlphaISA::PcPAL(regs.pc); }
+    void ev5_trap(Fault fault);
+    bool simPalCheck(int palFunc);
+#endif
+
+    /** Meant to be more generic trap function to be
+     *  called when an instruction faults.
+     *  @param fault The fault generated by executing the instruction.
+     *  @todo How to do this properly so it's dependent upon ISA only?
+     */
+
+    void trap(Fault fault);
+
+#if !FULL_SYSTEM
+    TheISA::IntReg getSyscallArg(int i)
+    {
+        return regs.intRegFile[TheISA::ArgumentReg0 + i];
+    }
+
+    // used to shift args for indirect syscall
+    void setSyscallArg(int i, TheISA::IntReg val)
+    {
+        regs.intRegFile[TheISA::ArgumentReg0 + i] = val;
+    }
+
+    void setSyscallReturn(SyscallReturn return_value)
+    {
+        // check for error condition.  Alpha syscall convention is to
+        // indicate success/failure in reg a3 (r19) and put the
+        // return value itself in the standard return value reg (v0).
+        const int RegA3 = 19;	// only place this is used
+        if (return_value.successful()) {
+            // no error
+            regs.intRegFile[RegA3] = 0;
+            regs.intRegFile[TheISA::ReturnValueReg] = return_value.value();
+        } else {
+            // got an error, return details
+            regs.intRegFile[RegA3] = (TheISA::IntReg) -1;
+            regs.intRegFile[TheISA::ReturnValueReg] = -return_value.value();
+        }
+    }
+
+    void syscall()
+    {
+        process->syscall(proxy);
+    }
+
+    Counter readFuncExeInst() { return func_exe_inst; }
+
+    void setFuncExeInst(Counter new_val) { func_exe_inst = new_val; }
+#endif
+};
+
+
+// for non-speculative execution context, spec_mode is always false
+inline bool
+CPUExecContext::misspeculating()
+{
+    return false;
+}
+
+#endif // __CPU_CPU_EXEC_CONTEXT_HH__
diff --git a/cpu/exec_context.hh b/cpu/exec_context.hh
index 88b12c301..9c96b5c42 100644
--- a/cpu/exec_context.hh
+++ b/cpu/exec_context.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001-2005 The Regents of The University of Michigan
+ * Copyright (c) 2006 The Regents of The University of Michigan
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -30,46 +30,29 @@
 #define __CPU_EXEC_CONTEXT_HH__
 
 #include "config/full_system.hh"
-#include "mem/functional/functional.hh"
 #include "mem/mem_req.hh"
+#include "sim/faults.hh"
 #include "sim/host.hh"
 #include "sim/serialize.hh"
-#include "arch/isa_traits.hh"
-//#include "arch/isa_registers.hh"
 #include "sim/byteswap.hh"
 
 // forward declaration: see functional_memory.hh
+// @todo: Figure out a more architecture independent way to obtain the ITB and
+// DTB pointers.
+class AlphaDTB;
+class AlphaITB;
+class BaseCPU;
 class FunctionalMemory;
 class PhysicalMemory;
-class BaseCPU;
-
-#if FULL_SYSTEM
-
-#include "sim/system.hh"
-#include "targetarch/alpha_memory.hh"
-
-class FunctionProfile;
-class ProfileNode;
-class MemoryController;
-namespace Kernel { class Binning; class Statistics; }
-
-#else // !FULL_SYSTEM
-
-#include "sim/process.hh"
-
-#endif // FULL_SYSTEM
-
-//
-// The ExecContext object represents a functional context for
-// instruction execution.  It incorporates everything required for
-// architecture-level functional simulation of a single thread.
-//
+class Process;
+class System;
 
 class ExecContext
 {
   protected:
     typedef TheISA::RegFile RegFile;
     typedef TheISA::MachInst MachInst;
+    typedef TheISA::IntReg IntReg;
     typedef TheISA::MiscRegFile MiscRegFile;
     typedef TheISA::MiscReg MiscReg;
   public:
@@ -86,7 +69,7 @@ class ExecContext
         Active,
 
         /// Temporarily inactive.  Entered while waiting for
-        /// initialization,synchronization, etc.
+        /// synchronization, etc.
         Suspended,
 
         /// Permanently shut down.  Entered when target executes
@@ -95,392 +78,326 @@ class ExecContext
         Halted
     };
 
-  private:
-    Status _status;
+    virtual ~ExecContext() { };
 
-  public:
-    Status status() const { return _status; }
+    virtual BaseCPU *getCpuPtr() = 0;
+
+    virtual void setCpuId(int id) = 0;
 
-    void setStatus(Status newStatus) { _status = newStatus; }
+    virtual int readCpuId() = 0;
+
+    virtual FunctionalMemory *getMemPtr() = 0;
+
+#if FULL_SYSTEM
+    virtual System *getSystemPtr() = 0;
+
+    virtual PhysicalMemory *getPhysMemPtr() = 0;
+
+    virtual AlphaITB *getITBPtr() = 0;
+
+    virtual AlphaDTB * getDTBPtr() = 0;
+#else
+    virtual Process *getProcessPtr() = 0;
+#endif
+
+    virtual Status status() const = 0;
 
     /// Set the status to Active.  Optional delay indicates number of
     /// cycles to wait before beginning execution.
-    void activate(int delay = 1);
+    virtual void activate(int delay = 1) = 0;
 
     /// Set the status to Suspended.
-    void suspend();
+    virtual void suspend() = 0;
 
     /// Set the status to Unallocated.
-    void deallocate();
+    virtual void deallocate() = 0;
 
     /// Set the status to Halted.
-    void halt();
+    virtual void halt() = 0;
 
-  public:
-    RegFile regs;	// correct-path register context
+#if FULL_SYSTEM
+    virtual void dumpFuncProfile() = 0;
+#endif
 
-    // pointer to CPU associated with this context
-    BaseCPU *cpu;
+    virtual void takeOverFrom(ExecContext *oldContext) = 0;
 
-    // Current instruction
-    MachInst inst;
+    virtual void regStats(const std::string &name) = 0;
 
-    // Index of hardware thread context on the CPU that this represents.
-    int thread_num;
+    virtual void serialize(std::ostream &os) = 0;
+    virtual void unserialize(Checkpoint *cp, const std::string &section) = 0;
 
-    // ID of this context w.r.t. the System or Process object to which
-    // it belongs.  For full-system mode, this is the system CPU ID.
-    int cpu_id;
+    virtual int getThreadNum() = 0;
 
-#if FULL_SYSTEM
-    FunctionalMemory *mem;
-    AlphaITB *itb;
-    AlphaDTB *dtb;
-    System *system;
-
-    // the following two fields are redundant, since we can always
-    // look them up through the system pointer, but we'll leave them
-    // here for now for convenience
-    MemoryController *memctrl;
-    PhysicalMemory *physmem;
-
-    Kernel::Binning *kernelBinning;
-    Kernel::Statistics *kernelStats;
-    bool bin;
-    bool fnbin;
-
-    FunctionProfile *profile;
-    ProfileNode *profileNode;
-    Addr profilePC;
-    void dumpFuncProfile();
+    virtual bool validInstAddr(Addr addr) = 0;
+    virtual bool validDataAddr(Addr addr) = 0;
+    virtual int getInstAsid() = 0;
+    virtual int getDataAsid() = 0;
 
-#else
-    Process *process;
+    virtual Fault translateInstReq(MemReqPtr &req) = 0;
+
+    virtual Fault translateDataReadReq(MemReqPtr &req) = 0;
+
+    virtual Fault translateDataWriteReq(MemReqPtr &req) = 0;
+
+    virtual TheISA::MachInst getInst() = 0;
+
+    virtual void copyArchRegs(ExecContext *xc) = 0;
+
+    virtual void clearArchRegs() = 0;
+
+    //
+    // New accessors for new decoder.
+    //
+    virtual uint64_t readIntReg(int reg_idx) = 0;
+
+    virtual float readFloatRegSingle(int reg_idx) = 0;
 
-    FunctionalMemory *mem;	// functional storage for process address space
+    virtual double readFloatRegDouble(int reg_idx) = 0;
 
-    // Address space ID.  Note that this is used for TIMING cache
-    // simulation only; all functional memory accesses should use
-    // one of the FunctionalMemory pointers above.
-    short asid;
+    virtual uint64_t readFloatRegInt(int reg_idx) = 0;
 
+    virtual void setIntReg(int reg_idx, uint64_t val) = 0;
+
+    virtual void setFloatRegSingle(int reg_idx, float val) = 0;
+
+    virtual void setFloatRegDouble(int reg_idx, double val) = 0;
+
+    virtual void setFloatRegInt(int reg_idx, uint64_t val) = 0;
+
+    virtual uint64_t readPC() = 0;
+
+    virtual void setPC(uint64_t val) = 0;
+
+    virtual uint64_t readNextPC() = 0;
+
+    virtual void setNextPC(uint64_t val) = 0;
+
+    virtual MiscReg readMiscReg(int misc_reg) = 0;
+
+    virtual MiscReg readMiscRegWithEffect(int misc_reg, Fault &fault) = 0;
+
+    virtual Fault setMiscReg(int misc_reg, const MiscReg &val) = 0;
+
+    virtual Fault setMiscRegWithEffect(int misc_reg, const MiscReg &val) = 0;
+
+    virtual unsigned readStCondFailures() = 0;
+
+    virtual void setStCondFailures(unsigned sc_failures) = 0;
+
+#if FULL_SYSTEM
+    virtual int readIntrFlag() = 0;
+    virtual void setIntrFlag(int val) = 0;
+    virtual Fault hwrei() = 0;
+    virtual bool inPalMode() = 0;
+    virtual void ev5_trap(Fault fault) = 0;
+    virtual bool simPalCheck(int palFunc) = 0;
 #endif
 
-    /**
-     * Temporary storage to pass the source address from copy_load to
-     * copy_store.
-     * @todo Remove this temporary when we have a better way to do it.
-     */
-    Addr copySrcAddr;
-    /**
-     * Temp storage for the physical source address of a copy.
-     * @todo Remove this temporary when we have a better way to do it.
+    virtual bool misspeculating() = 0;
+
+    /** Meant to be more generic trap function to be
+     *  called when an instruction faults.
+     *  @param fault The fault generated by executing the instruction.
+     *  @todo How to do this properly so it's dependent upon ISA only?
      */
-    Addr copySrcPhysAddr;
 
+    virtual void trap(Fault fault) = 0;
 
-    /*
-     * number of executed instructions, for matching with syscall trace
-     * points in EIO files.
-     */
-    Counter func_exe_inst;
+#if !FULL_SYSTEM
+    virtual IntReg getSyscallArg(int i) = 0;
 
-    //
-    // Count failed store conditionals so we can warn of apparent
-    // application deadlock situations.
-    unsigned storeCondFailures;
+    // used to shift args for indirect syscall
+    virtual void setSyscallArg(int i, IntReg val) = 0;
 
-    // constructor: initialize context from given process structure
-#if FULL_SYSTEM
-    ExecContext(BaseCPU *_cpu, int _thread_num, System *_system,
-                AlphaITB *_itb, AlphaDTB *_dtb, FunctionalMemory *_dem);
-#else
-    ExecContext(BaseCPU *_cpu, int _thread_num, Process *_process, int _asid);
-    ExecContext(BaseCPU *_cpu, int _thread_num, FunctionalMemory *_mem,
-                int _asid);
+    virtual void setSyscallReturn(SyscallReturn return_value) = 0;
+
+    virtual void syscall() = 0;
+
+    virtual Counter readFuncExeInst() = 0;
+
+    virtual void setFuncExeInst(Counter new_val) = 0;
 #endif
-    virtual ~ExecContext();
+};
 
-    virtual void takeOverFrom(ExecContext *oldContext);
+template <class XC>
+class ProxyExecContext : public ExecContext
+{
+  public:
+    ProxyExecContext(XC *actual_xc)
+    { actualXC = actual_xc; }
 
-    void regStats(const std::string &name);
+  private:
+    XC *actualXC;
 
-    void serialize(std::ostream &os);
-    void unserialize(Checkpoint *cp, const std::string &section);
+  public:
 
-#if FULL_SYSTEM
-    bool validInstAddr(Addr addr) { return true; }
-    bool validDataAddr(Addr addr) { return true; }
-    int getInstAsid() { return regs.instAsid(); }
-    int getDataAsid() { return regs.dataAsid(); }
+    BaseCPU *getCpuPtr() { return actualXC->getCpuPtr(); }
 
-    Fault translateInstReq(MemReqPtr &req)
-    {
-        return itb->translate(req);
-    }
+    void setCpuId(int id) { actualXC->setCpuId(id); }
 
-    Fault translateDataReadReq(MemReqPtr &req)
-    {
-        return dtb->translate(req, false);
-    }
+    int readCpuId() { return actualXC->readCpuId(); }
 
-    Fault translateDataWriteReq(MemReqPtr &req)
-    {
-        return dtb->translate(req, true);
-    }
+    FunctionalMemory *getMemPtr() { return actualXC->getMemPtr(); }
 
-#else
-    bool validInstAddr(Addr addr)
-    { return process->validInstAddr(addr); }
+#if FULL_SYSTEM
+    System *getSystemPtr() { return actualXC->getSystemPtr(); }
 
-    bool validDataAddr(Addr addr)
-    { return process->validDataAddr(addr); }
+    PhysicalMemory *getPhysMemPtr() { return actualXC->getPhysMemPtr(); }
 
-    int getInstAsid() { return asid; }
-    int getDataAsid() { return asid; }
+    AlphaITB *getITBPtr() { return actualXC->getITBPtr(); }
 
-    Fault dummyTranslation(MemReqPtr &req)
-    {
-#if 0
-        assert((req->vaddr >> 48 & 0xffff) == 0);
+    AlphaDTB *getDTBPtr() { return actualXC->getDTBPtr(); }
+#else
+    Process *getProcessPtr() { return actualXC->getProcessPtr(); }
 #endif
 
-        // put the asid in the upper 16 bits of the paddr
-        req->paddr = req->vaddr & ~((Addr)0xffff << sizeof(Addr) * 8 - 16);
-        req->paddr = req->paddr | (Addr)req->asid << sizeof(Addr) * 8 - 16;
-        return NoFault;
-    }
-    Fault translateInstReq(MemReqPtr &req)
-    {
-        return dummyTranslation(req);
-    }
-    Fault translateDataReadReq(MemReqPtr &req)
-    {
-        return dummyTranslation(req);
-    }
-    Fault translateDataWriteReq(MemReqPtr &req)
-    {
-        return dummyTranslation(req);
-    }
+    Status status() const { return actualXC->status(); }
 
-#endif
+    /// Set the status to Active.  Optional delay indicates number of
+    /// cycles to wait before beginning execution.
+    void activate(int delay = 1) { actualXC->activate(delay); }
 
-    template <class T>
-    Fault read(MemReqPtr &req, T &data)
-    {
-#if FULL_SYSTEM && defined(TARGET_ALPHA)
-        if (req->flags & LOCKED) {
-            MiscRegFile *cregs = &req->xc->regs.miscRegs;
-            cregs->setReg(TheISA::Lock_Addr_DepTag, req->paddr);
-            cregs->setReg(TheISA::Lock_Flag_DepTag, true);
-        }
-#endif
+    /// Set the status to Suspended.
+    void suspend() { actualXC->suspend(); }
 
-        Fault error;
-        error = mem->read(req, data);
-        data = LittleEndianGuest::gtoh(data);
-        return error;
-    }
+    /// Set the status to Unallocated.
+    void deallocate() { actualXC->deallocate(); }
 
-    template <class T>
-    Fault write(MemReqPtr &req, T &data)
-    {
-#if FULL_SYSTEM && defined(TARGET_ALPHA)
-
-        MiscRegFile *cregs;
-
-        // If this is a store conditional, act appropriately
-        if (req->flags & LOCKED) {
-            cregs = &req->xc->regs.miscRegs;
-
-            if (req->flags & UNCACHEABLE) {
-                // Don't update result register (see stq_c in isa_desc)
-                req->result = 2;
-                req->xc->storeCondFailures = 0;//Needed? [RGD]
-            } else {
-                bool lock_flag = cregs->readReg(TheISA::Lock_Flag_DepTag);
-                Addr lock_addr = cregs->readReg(TheISA::Lock_Addr_DepTag);
-                req->result = lock_flag;
-                if (!lock_flag ||
-                    ((lock_addr & ~0xf) != (req->paddr & ~0xf))) {
-                    cregs->setReg(TheISA::Lock_Flag_DepTag, false);
-                    if (((++req->xc->storeCondFailures) % 100000) == 0) {
-                        std::cerr << "Warning: "
-                                  << req->xc->storeCondFailures
-                                  << " consecutive store conditional failures "
-                                  << "on cpu " << req->xc->cpu_id
-                                  << std::endl;
-                    }
-                    return NoFault;
-                }
-                else req->xc->storeCondFailures = 0;
-            }
-        }
-
-        // Need to clear any locked flags on other proccessors for
-        // this address.  Only do this for succsful Store Conditionals
-        // and all other stores (WH64?).  Unsuccessful Store
-        // Conditionals would have returned above, and wouldn't fall
-        // through.
-        for (int i = 0; i < system->execContexts.size(); i++){
-            cregs = &system->execContexts[i]->regs.miscRegs;
-            if ((cregs->readReg(TheISA::Lock_Addr_DepTag) & ~0xf) ==
-                (req->paddr & ~0xf)) {
-                cregs->setReg(TheISA::Lock_Flag_DepTag, false);
-            }
-        }
+    /// Set the status to Halted.
+    void halt() { actualXC->halt(); }
 
+#if FULL_SYSTEM
+    void dumpFuncProfile() { actualXC->dumpFuncProfile(); }
 #endif
-        return mem->write(req, (T)LittleEndianGuest::htog(data));
-    }
 
-    virtual bool misspeculating();
+    void takeOverFrom(ExecContext *oldContext)
+    { actualXC->takeOverFrom(oldContext); }
 
+    void regStats(const std::string &name) { actualXC->regStats(name); }
 
-    MachInst getInst() { return inst; }
+    void serialize(std::ostream &os) { actualXC->serialize(os); }
+    void unserialize(Checkpoint *cp, const std::string &section)
+    { actualXC->unserialize(cp, section); }
 
-    void setInst(MachInst new_inst)
-    {
-        inst = new_inst;
-    }
+    int getThreadNum() { return actualXC->getThreadNum(); }
 
-    Fault instRead(MemReqPtr &req)
-    {
-        return mem->read(req, inst);
-    }
+    bool validInstAddr(Addr addr) { return actualXC->validInstAddr(addr); }
+    bool validDataAddr(Addr addr) { return actualXC->validDataAddr(addr); }
+    int getInstAsid() { return actualXC->getInstAsid(); }
+    int getDataAsid() { return actualXC->getDataAsid(); }
+
+    Fault translateInstReq(MemReqPtr &req)
+    { return actualXC->translateInstReq(req); }
+
+    Fault translateDataReadReq(MemReqPtr &req)
+    { return actualXC->translateDataReadReq(req); }
+
+    Fault translateDataWriteReq(MemReqPtr &req)
+    { return actualXC->translateDataWriteReq(req); }
+
+    // @todo: Do I need this?
+    MachInst getInst() { return actualXC->getInst(); }
+
+    // @todo: Do I need this?
+    void copyArchRegs(ExecContext *xc) { actualXC->copyArchRegs(xc); }
+
+    void clearArchRegs() { actualXC->clearArchRegs(); }
 
     //
     // New accessors for new decoder.
     //
     uint64_t readIntReg(int reg_idx)
-    {
-        return regs.intRegFile[reg_idx];
-    }
+    { return actualXC->readIntReg(reg_idx); }
 
     float readFloatRegSingle(int reg_idx)
-    {
-        return (float)regs.floatRegFile.d[reg_idx];
-    }
+    { return actualXC->readFloatRegSingle(reg_idx); }
 
     double readFloatRegDouble(int reg_idx)
-    {
-        return regs.floatRegFile.d[reg_idx];
-    }
+    { return actualXC->readFloatRegDouble(reg_idx); }
 
     uint64_t readFloatRegInt(int reg_idx)
-    {
-        return regs.floatRegFile.q[reg_idx];
-    }
+    { return actualXC->readFloatRegInt(reg_idx); }
 
     void setIntReg(int reg_idx, uint64_t val)
-    {
-        regs.intRegFile[reg_idx] = val;
-    }
+    { actualXC->setIntReg(reg_idx, val); }
 
     void setFloatRegSingle(int reg_idx, float val)
-    {
-        regs.floatRegFile.d[reg_idx] = (double)val;
-    }
+    { actualXC->setFloatRegSingle(reg_idx, val); }
 
     void setFloatRegDouble(int reg_idx, double val)
-    {
-        regs.floatRegFile.d[reg_idx] = val;
-    }
+    { actualXC->setFloatRegDouble(reg_idx, val); }
 
     void setFloatRegInt(int reg_idx, uint64_t val)
-    {
-        regs.floatRegFile.q[reg_idx] = val;
-    }
+    { actualXC->setFloatRegInt(reg_idx, val); }
 
-    uint64_t readPC()
-    {
-        return regs.pc;
-    }
+    uint64_t readPC() { return actualXC->readPC(); }
 
-    void setNextPC(uint64_t val)
-    {
-        regs.npc = val;
-    }
+    void setPC(uint64_t val) { actualXC->setPC(val); }
+
+    uint64_t readNextPC() { return actualXC->readNextPC(); }
+
+    void setNextPC(uint64_t val) { actualXC->setNextPC(val); }
 
     MiscReg readMiscReg(int misc_reg)
-    {
-        return regs.miscRegs.readReg(misc_reg);
-    }
+    { return actualXC->readMiscReg(misc_reg); }
 
     MiscReg readMiscRegWithEffect(int misc_reg, Fault &fault)
-    {
-        return regs.miscRegs.readRegWithEffect(misc_reg, fault, this);
-    }
+    { return actualXC->readMiscRegWithEffect(misc_reg, fault); }
 
     Fault setMiscReg(int misc_reg, const MiscReg &val)
-    {
-        return regs.miscRegs.setReg(misc_reg, val);
-    }
+    { return actualXC->setMiscReg(misc_reg, val); }
 
     Fault setMiscRegWithEffect(int misc_reg, const MiscReg &val)
-    {
-        return regs.miscRegs.setRegWithEffect(misc_reg, val, this);
-    }
+    { return actualXC->setMiscRegWithEffect(misc_reg, val); }
+
+    unsigned readStCondFailures()
+    { return actualXC->readStCondFailures(); }
+
+    void setStCondFailures(unsigned sc_failures)
+    { actualXC->setStCondFailures(sc_failures); }
 
 #if FULL_SYSTEM
-    int readIntrFlag() { return regs.intrflag; }
-    void setIntrFlag(int val) { regs.intrflag = val; }
-    Fault hwrei();
-    bool inPalMode() { return AlphaISA::PcPAL(regs.pc); }
-    void ev5_trap(Fault fault);
-    bool simPalCheck(int palFunc);
+    int readIntrFlag() { return actualXC->readIntrFlag(); }
+
+    void setIntrFlag(int val) { actualXC->setIntrFlag(val); }
+
+    Fault hwrei() { return actualXC->hwrei(); }
+
+    bool inPalMode() { return actualXC->inPalMode(); }
+
+    void ev5_trap(Fault fault) { actualXC->ev5_trap(fault); }
+
+    bool simPalCheck(int palFunc) { return actualXC->simPalCheck(palFunc); }
 #endif
 
+    // @todo: Fix this!
+    bool misspeculating() { return false; }
+
     /** Meant to be more generic trap function to be
      *  called when an instruction faults.
      *  @param fault The fault generated by executing the instruction.
      *  @todo How to do this properly so it's dependent upon ISA only?
      */
 
-    void trap(Fault fault);
+    void trap(Fault fault) { actualXC->trap(fault); }
 
 #if !FULL_SYSTEM
-    TheISA::IntReg getSyscallArg(int i)
-    {
-        return regs.intRegFile[TheISA::ArgumentReg0 + i];
-    }
+    IntReg getSyscallArg(int i) { return actualXC->getSyscallArg(i); }
 
     // used to shift args for indirect syscall
-    void setSyscallArg(int i, TheISA::IntReg val)
-    {
-        regs.intRegFile[TheISA::ArgumentReg0 + i] = val;
-    }
+    void setSyscallArg(int i, IntReg val)
+    { actualXC->setSyscallArg(i, val); }
 
     void setSyscallReturn(SyscallReturn return_value)
-    {
-        // check for error condition.  Alpha syscall convention is to
-        // indicate success/failure in reg a3 (r19) and put the
-        // return value itself in the standard return value reg (v0).
-        const int RegA3 = 19;	// only place this is used
-        if (return_value.successful()) {
-            // no error
-            regs.intRegFile[RegA3] = 0;
-            regs.intRegFile[TheISA::ReturnValueReg] = return_value.value();
-        } else {
-            // got an error, return details
-            regs.intRegFile[RegA3] = (TheISA::IntReg) -1;
-            regs.intRegFile[TheISA::ReturnValueReg] = -return_value.value();
-        }
-    }
-
-    void syscall()
-    {
-        process->syscall(this);
-    }
-#endif
-};
+    { actualXC->setSyscallReturn(return_value); }
 
+    void syscall() { actualXC->syscall(); }
 
-// for non-speculative execution context, spec_mode is always false
-inline bool
-ExecContext::misspeculating()
-{
-    return false;
-}
+    Counter readFuncExeInst() { return actualXC->readFuncExeInst(); }
 
-#endif // __CPU_EXEC_CONTEXT_HH__
+    void setFuncExeInst(Counter new_val)
+    { return actualXC->setFuncExeInst(new_val); }
+#endif
+};
+
+#endif
diff --git a/cpu/exetrace.cc b/cpu/exetrace.cc
index 8393a1b85..84b5eacf7 100644
--- a/cpu/exetrace.cc
+++ b/cpu/exetrace.cc
@@ -34,7 +34,6 @@
 #include "encumbered/cpu/full/spec_state.hh"
 #include "encumbered/cpu/full/issue.hh"
 #include "cpu/exetrace.hh"
-#include "cpu/exec_context.hh"
 #include "base/loader/symtab.hh"
 #include "cpu/base.hh"
 #include "cpu/static_inst.hh"
diff --git a/cpu/intr_control.cc b/cpu/intr_control.cc
index 5f17c7212..d1866a0c4 100644
--- a/cpu/intr_control.cc
+++ b/cpu/intr_control.cc
@@ -48,7 +48,7 @@ void
 IntrControl::post(int int_num, int index)
 {
     std::vector<ExecContext *> &xcvec = cpu->system->execContexts;
-    BaseCPU *temp = xcvec[0]->cpu;
+    BaseCPU *temp = xcvec[0]->getCpuPtr();
     temp->post_interrupt(int_num, index);
 }
 
@@ -56,7 +56,7 @@ void
 IntrControl::post(int cpu_id, int int_num, int index)
 {
     std::vector<ExecContext *> &xcvec = cpu->system->execContexts;
-    BaseCPU *temp = xcvec[cpu_id]->cpu;
+    BaseCPU *temp = xcvec[cpu_id]->getCpuPtr();
     temp->post_interrupt(int_num, index);
 }
 
@@ -64,7 +64,7 @@ void
 IntrControl::clear(int int_num, int index)
 {
     std::vector<ExecContext *> &xcvec = cpu->system->execContexts;
-    BaseCPU *temp = xcvec[0]->cpu;
+    BaseCPU *temp = xcvec[0]->getCpuPtr();
     temp->clear_interrupt(int_num, index);
 }
 
@@ -72,7 +72,7 @@ void
 IntrControl::clear(int cpu_id, int int_num, int index)
 {
     std::vector<ExecContext *> &xcvec = cpu->system->execContexts;
-    BaseCPU *temp = xcvec[cpu_id]->cpu;
+    BaseCPU *temp = xcvec[cpu_id]->getCpuPtr();
     temp->clear_interrupt(int_num, index);
 }
 
diff --git a/cpu/intr_control.hh b/cpu/intr_control.hh
index 2a57a8dfc..5ec4e14cb 100644
--- a/cpu/intr_control.hh
+++ b/cpu/intr_control.hh
@@ -34,7 +34,6 @@
 #include "cpu/base.hh"
 #include "sim/sim_object.hh"
 #include "sim/system.hh"
-#include "cpu/exec_context.hh"
 
 
 class IntrControl : public SimObject
diff --git a/cpu/memtest/memtest.cc b/cpu/memtest/memtest.cc
index 5a4024587..94b66b70b 100644
--- a/cpu/memtest/memtest.cc
+++ b/cpu/memtest/memtest.cc
@@ -36,7 +36,7 @@
 
 #include "base/misc.hh"
 #include "base/statistics.hh"
-#include "cpu/exec_context.hh"
+#include "cpu/cpu_exec_context.hh"
 #include "cpu/memtest/memtest.hh"
 #include "mem/cache/base_cache.hh"
 #include "sim/builder.hh"
@@ -79,7 +79,7 @@ MemTest::MemTest(const string &name,
     vector<string> cmd;
     cmd.push_back("/bin/ls");
     vector<string> null_vec;
-    xc = new ExecContext(NULL, 0, mainMem, 0);
+    cpuXC = new CPUExecContext(NULL, 0, mainMem, 0);
 
     blockSize = cacheInterface->getBlockSize();
     blockAddrMask = blockSize - 1;
@@ -269,7 +269,7 @@ MemTest::tick()
     req->data = new uint8_t[req->size];
     req->paddr &= ~(req->size - 1);
     req->time = curTick;
-    req->xc = xc;
+    req->xc = cpuXC->getProxy();
 
     if (cmd < percentReads) {
         // read
diff --git a/cpu/memtest/memtest.hh b/cpu/memtest/memtest.hh
index 7abcf017a..cdb40a26a 100644
--- a/cpu/memtest/memtest.hh
+++ b/cpu/memtest/memtest.hh
@@ -83,7 +83,7 @@ class MemTest : public SimObject
     MemInterface *cacheInterface;
     FunctionalMemory *mainMem;
     FunctionalMemory *checkMem;
-    ExecContext *xc;
+    CPUExecContext *cpuXC;
 
     unsigned size;		// size of testing memory region
 
diff --git a/cpu/o3/alpha_cpu.hh b/cpu/o3/alpha_cpu.hh
index 47ea532a6..75a4d72c2 100644
--- a/cpu/o3/alpha_cpu.hh
+++ b/cpu/o3/alpha_cpu.hh
@@ -152,13 +152,13 @@ class AlphaFullCPU : public FullO3CPU<Impl>
     // set the register.
     IntReg getSyscallArg(int i)
     {
-        return this->xc->regs.intRegFile[AlphaISA::ArgumentReg0 + i];
+        return this->cpuXC->readIntReg(AlphaISA::ArgumentReg0 + i);
     }
 
     // used to shift args for indirect syscall
     void setSyscallArg(int i, IntReg val)
     {
-        this->xc->regs.intRegFile[AlphaISA::ArgumentReg0 + i] = val;
+        this->cpuXC->setIntReg(AlphaISA::ArgumentReg0 + i, val);
     }
 
     void setSyscallReturn(int64_t return_value)
@@ -169,12 +169,12 @@ class AlphaFullCPU : public FullO3CPU<Impl>
         const int RegA3 = 19;	// only place this is used
         if (return_value >= 0) {
             // no error
-            this->xc->regs.intRegFile[RegA3] = 0;
-            this->xc->regs.intRegFile[AlphaISA::ReturnValueReg] = return_value;
+            this->cpuXC->setIntReg(RegA3, 0);
+            this->cpuXC->setIntReg(AlphaISA::ReturnValueReg, return_value);
         } else {
             // got an error, return details
-            this->xc->regs.intRegFile[RegA3] = (IntReg) -1;
-            this->xc->regs.intRegFile[AlphaISA::ReturnValueReg] = -return_value;
+            this->cpuXC->setIntReg(RegA3, (IntReg) -1);
+            this->cpuXC->setIntReg(AlphaISA::ReturnValueReg, -return_value);
         }
     }
 
@@ -208,9 +208,8 @@ class AlphaFullCPU : public FullO3CPU<Impl>
     {
 #if FULL_SYSTEM && defined(TARGET_ALPHA)
         if (req->flags & LOCKED) {
-            MiscRegFile *cregs = &req->xc->regs.miscRegs;
-            cregs->setReg(TheISA::Lock_Addr_DepTag, req->paddr);
-            cregs->setReg(TheISA::Lock_Flag_DepTag, true);
+            req->xc->setMiscReg(TheISA::Lock_Addr_DepTag, req->paddr);
+            req->xc->setMiscReg(TheISA::Lock_Flag_DepTag, true);
         }
 #endif
 
@@ -230,34 +229,34 @@ class AlphaFullCPU : public FullO3CPU<Impl>
     Fault write(MemReqPtr &req, T &data)
     {
 #if FULL_SYSTEM && defined(TARGET_ALPHA)
-
-        MiscRegFile *cregs;
+        ExecContext *xc;
 
         // If this is a store conditional, act appropriately
         if (req->flags & LOCKED) {
-            cregs = &req->xc->regs.miscRegs;
+            xc = req->xc;
 
             if (req->flags & UNCACHEABLE) {
                 // Don't update result register (see stq_c in isa_desc)
                 req->result = 2;
-                req->xc->storeCondFailures = 0;//Needed? [RGD]
+                xc->setStCondFailures(0);//Needed? [RGD]
             } else {
-                bool lock_flag = cregs->readReg(TheISA::Lock_Flag_DepTag);
-                Addr lock_addr = cregs->readReg(TheISA::Lock_Addr_DepTag);
+                bool lock_flag = xc->readMiscReg(TheISA::Lock_Flag_DepTag);
+                Addr lock_addr = xc->readMiscReg(TheISA::Lock_Addr_DepTag);
                 req->result = lock_flag;
                 if (!lock_flag ||
                     ((lock_addr & ~0xf) != (req->paddr & ~0xf))) {
-                    cregs->setReg(TheISA::Lock_Flag_DepTag, false);
-                    if (((++req->xc->storeCondFailures) % 100000) == 0) {
+                    xc->setMiscReg(TheISA::Lock_Flag_DepTag, false);
+                    xc->setStCondFailures(xc->readStCondFailures() + 1);
+                    if (((xc->readStCondFailures()) % 100000) == 0) {
                         std::cerr << "Warning: "
-                                  << req->xc->storeCondFailures
+                                  << xc->readStCondFailures()
                                   << " consecutive store conditional failures "
-                                  << "on cpu " << req->xc->cpu_id
+                                  << "on cpu " << req->xc->readCpuId()
                                   << std::endl;
                     }
                     return NoFault;
                 }
-                else req->xc->storeCondFailures = 0;
+                else xc->setStCondFailures(0);
             }
         }
 
@@ -267,10 +266,10 @@ class AlphaFullCPU : public FullO3CPU<Impl>
         // Conditionals would have returned above, and wouldn't fall
         // through.
         for (int i = 0; i < this->system->execContexts.size(); i++){
-            cregs = &this->system->execContexts[i]->regs.miscRegs;
-            if ((cregs->readReg(TheISA::Lock_Addr_DepTag) & ~0xf) ==
+            xc = this->system->execContexts[i];
+            if ((xc->readMiscReg(TheISA::Lock_Addr_DepTag) & ~0xf) ==
                 (req->paddr & ~0xf)) {
-                cregs->setReg(TheISA::Lock_Flag_DepTag, false);
+                xc->setMiscReg(TheISA::Lock_Flag_DepTag, false);
             }
         }
 
diff --git a/cpu/o3/alpha_cpu_builder.cc b/cpu/o3/alpha_cpu_builder.cc
index 3547fb1b5..7e687ad2b 100644
--- a/cpu/o3/alpha_cpu_builder.cc
+++ b/cpu/o3/alpha_cpu_builder.cc
@@ -30,7 +30,6 @@
 #include "base/loader/symtab.hh"
 #include "base/misc.hh"
 #include "cpu/base.hh"
-#include "cpu/exec_context.hh"
 #include "cpu/exetrace.hh"
 #include "cpu/o3/alpha_cpu.hh"
 #include "cpu/o3/alpha_impl.hh"
diff --git a/cpu/o3/alpha_cpu_impl.hh b/cpu/o3/alpha_cpu_impl.hh
index bd4e34914..271b542ab 100644
--- a/cpu/o3/alpha_cpu_impl.hh
+++ b/cpu/o3/alpha_cpu_impl.hh
@@ -165,7 +165,7 @@ AlphaFullCPU<Impl>::copyToXC()
     for (int i = 0; i < AlphaISA::NumIntRegs; ++i)
     {
         renamed_reg = this->renameMap.lookup(i);
-        this->xc->regs.intRegFile[i] = this->regFile.readIntReg(renamed_reg);
+        this->cpuXC->setIntReg(i, this->regFile.readIntReg(renamed_reg));
         DPRINTF(FullCPU, "FullCPU: Copying register %i, has data %lli.\n",
                 renamed_reg, this->regFile.intRegFile[renamed_reg]);
     }
@@ -174,21 +174,23 @@ AlphaFullCPU<Impl>::copyToXC()
     for (int i = 0; i < AlphaISA::NumFloatRegs; ++i)
     {
         renamed_reg = this->renameMap.lookup(i + AlphaISA::FP_Base_DepTag);
-        this->xc->regs.floatRegFile.d[i] =
-            this->regFile.readFloatRegDouble(renamed_reg);
-        this->xc->regs.floatRegFile.q[i] =
-            this->regFile.readFloatRegInt(renamed_reg);
+        this->cpuXC->setFloatRegDouble(i,
+            this->regFile.readFloatRegDouble(renamed_reg));
+        this->cpuXC->setFloatRegInt(i,
+            this->regFile.readFloatRegInt(renamed_reg));
     }
 /*
-    this->xc->regs.miscRegs.fpcr = this->regFile.miscRegs.fpcr;
-    this->xc->regs.miscRegs.uniq = this->regFile.miscRegs.uniq;
-    this->xc->regs.miscRegs.lock_flag = this->regFile.miscRegs.lock_flag;
-    this->xc->regs.miscRegs.lock_addr = this->regFile.miscRegs.lock_addr;
+    this->cpuXC->regs.miscRegs.fpcr = this->regFile.miscRegs.fpcr;
+    this->cpuXC->regs.miscRegs.uniq = this->regFile.miscRegs.uniq;
+    this->cpuXC->regs.miscRegs.lock_flag = this->regFile.miscRegs.lock_flag;
+    this->cpuXC->regs.miscRegs.lock_addr = this->regFile.miscRegs.lock_addr;
 */
-    this->xc->regs.pc = this->rob.readHeadPC();
-    this->xc->regs.npc = this->xc->regs.pc+4;
+    this->cpuXC->setPC(this->rob.readHeadPC());
+    this->cpuXC->setNextPC(this->cpuXC->readPC()+4);
 
-    this->xc->func_exe_inst = this->funcExeInst;
+#if !FULL_SYSTEM
+    this->cpuXC->setFuncExeInst(this->funcExeInst);
+#endif
 }
 
 // This function will probably mess things up unless the ROB is empty and
@@ -207,9 +209,9 @@ AlphaFullCPU<Impl>::copyFromXC()
         DPRINTF(FullCPU, "FullCPU: Copying over register %i, had data %lli, "
                 "now has data %lli.\n",
                 renamed_reg, this->regFile.intRegFile[renamed_reg],
-                this->xc->regs.intRegFile[i]);
+                this->cpuXC->readIntReg(i));
 
-        this->regFile.setIntReg(renamed_reg, this->xc->regs.intRegFile[i]);
+        this->regFile.setIntReg(renamed_reg, this->cpuXC->readIntReg(i));
     }
 
     // Then loop through the floating point registers.
@@ -217,22 +219,23 @@ AlphaFullCPU<Impl>::copyFromXC()
     {
         renamed_reg = this->renameMap.lookup(i + AlphaISA::FP_Base_DepTag);
         this->regFile.setFloatRegDouble(renamed_reg,
-                                        this->xc->regs.floatRegFile.d[i]);
+                                        this->cpuXC->readFloatRegDouble(i));
         this->regFile.setFloatRegInt(renamed_reg,
-                                     this->xc->regs.floatRegFile.q[i]);
+                                     this->cpuXC->readFloatRegInt(i));
     }
     /*
     // Then loop through the misc registers.
-    this->regFile.miscRegs.fpcr = this->xc->regs.miscRegs.fpcr;
-    this->regFile.miscRegs.uniq = this->xc->regs.miscRegs.uniq;
-    this->regFile.miscRegs.lock_flag = this->xc->regs.miscRegs.lock_flag;
-    this->regFile.miscRegs.lock_addr = this->xc->regs.miscRegs.lock_addr;
+    this->regFile.miscRegs.fpcr = this->cpuXC->regs.miscRegs.fpcr;
+    this->regFile.miscRegs.uniq = this->cpuXC->regs.miscRegs.uniq;
+    this->regFile.miscRegs.lock_flag = this->cpuXC->regs.miscRegs.lock_flag;
+    this->regFile.miscRegs.lock_addr = this->cpuXC->regs.miscRegs.lock_addr;
     */
     // Then finally set the PC and the next PC.
-//    regFile.pc = xc->regs.pc;
-//    regFile.npc = xc->regs.npc;
-
-    this->funcExeInst = this->xc->func_exe_inst;
+//    regFile.pc = cpuXC->regs.pc;
+//    regFile.npc = cpuXC->regs.npc;
+#if !FULL_SYSTEM
+    this->funcExeInst = this->cpuXC->readFuncExeInst();
+#endif
 }
 
 #if FULL_SYSTEM
diff --git a/cpu/o3/cpu.cc b/cpu/o3/cpu.cc
index a8c620028..62d68bb33 100644
--- a/cpu/o3/cpu.cc
+++ b/cpu/o3/cpu.cc
@@ -35,10 +35,11 @@
 #endif
 #include "sim/root.hh"
 
+#include "cpu/cpu_exec_context.hh"
+#include "cpu/exec_context.hh"
 #include "cpu/o3/alpha_dyn_inst.hh"
 #include "cpu/o3/alpha_impl.hh"
 #include "cpu/o3/cpu.hh"
-#include "cpu/exec_context.hh"
 
 using namespace std;
 
@@ -103,7 +104,7 @@ FullO3CPU<Impl>::FullO3CPU(Params &params)
       renameQueue(5, 5),
       iewQueue(5, 5),
 
-      xc(NULL),
+      cpuXC(NULL),
 
       globalSeqNum(1),
 
@@ -134,8 +135,8 @@ FullO3CPU<Impl>::FullO3CPU(Params &params)
     for (int i = 0; i < this->number_of_threads; ++i) {
 #if FULL_SYSTEM
         assert(i == 0);
-        system->execContexts[i] =
-            new ExecContext(this, i, system, itb, dtb, mem);
+        thread[i] = new CPUExecContext(this, 0, system, itb, dtb, mem);
+        system->execContexts[i] = thread[i]->getProxy();
 
         execContexts.push_back(system->execContexts[i]);
 #else
@@ -143,21 +144,17 @@ FullO3CPU<Impl>::FullO3CPU(Params &params)
             DPRINTF(FullCPU, "FullCPU: Workload[%i]'s starting PC is %#x, "
                     "process is %#x",
                     i, params.workload[i]->prog_entry, thread[i]);
-            thread[i] = new ExecContext(this, i, params.workload[i], i);
+            thread[i] = new CPUExecContext(this, i, params.workload[i], i);
         }
         assert(params.workload[i]->getMemory() != NULL);
         assert(mem != NULL);
-        execContexts.push_back(thread[i]);
+        execContexts.push_back(thread[i]->getProxy());
 #endif // !FULL_SYSTEM
     }
 
     // Note that this is a hack so that my code which still uses xc-> will
     // still work.  I should remove this eventually
-#if FULL_SYSTEM
-    xc = system->execContexts[0];
-#else
-    xc = thread[0];
-#endif
+    cpuXC = thread[0];
 
     // The stages also need their CPU pointer setup.  However this must be
     // done at the upper level CPU because they have pointers to the upper
@@ -248,21 +245,21 @@ FullO3CPU<Impl>::init()
         // that it can start properly.
 #if FULL_SYSTEM
         ExecContext *src_xc = system->execContexts[0];
-        TheISA::initCPU(&src_xc->regs, src_xc->cpu_id);
+        TheISA::initCPU(src_xc, src_xc->readCpuId());
 #else
-        ExecContext *src_xc = thread[0];
+        ExecContext *src_xc = thread[0]->getProxy();
 #endif
         // First loop through the integer registers.
         for (int i = 0; i < TheISA::NumIntRegs; ++i)
         {
-            regFile.intRegFile[i] = src_xc->regs.intRegFile[i];
+            regFile.intRegFile[i] = src_xc->readIntReg(i);
         }
 
         // Then loop through the floating point registers.
         for (int i = 0; i < TheISA::NumFloatRegs; ++i)
         {
-            regFile.floatRegFile[i].d = src_xc->regs.floatRegFile.d[i];
-            regFile.floatRegFile[i].q = src_xc->regs.floatRegFile.q[i];
+            regFile.floatRegFile[i].d = src_xc->readFloatRegDouble(i);
+            regFile.floatRegFile[i].q = src_xc->readFloatRegInt(i);
         }
 /*
         // Then loop through the misc registers.
@@ -272,8 +269,8 @@ FullO3CPU<Impl>::init()
         regFile.miscRegs.lock_addr = src_xc->regs.miscRegs.lock_addr;
 */
         // Then finally set the PC and the next PC.
-        regFile.pc = src_xc->regs.pc;
-        regFile.npc = src_xc->regs.npc;
+        regFile.pc = src_xc->readPC();
+        regFile.npc = src_xc->readNextPC();
     }
 }
 
diff --git a/cpu/o3/cpu.hh b/cpu/o3/cpu.hh
index 09d9c3d66..45e21db7f 100644
--- a/cpu/o3/cpu.hh
+++ b/cpu/o3/cpu.hh
@@ -44,9 +44,9 @@
 #include "base/timebuf.hh"
 #include "config/full_system.hh"
 #include "cpu/base.hh"
+#include "cpu/cpu_exec_context.hh"
 #include "cpu/o3/comm.hh"
 #include "cpu/o3/cpu_policy.hh"
-#include "cpu/exec_context.hh"
 #include "sim/process.hh"
 
 #if FULL_SYSTEM
@@ -54,6 +54,7 @@
 using namespace EV5;
 #endif
 
+class ExecContext;
 class FunctionalMemory;
 class Process;
 
@@ -164,8 +165,8 @@ class FullO3CPU : public BaseFullCPU
     bool validDataAddr(Addr addr)
     { return thread[0]->validDataAddr(addr); }
 
-    int getInstAsid() { return thread[0]->asid; }
-    int getDataAsid() { return thread[0]->asid; }
+    int getInstAsid() { return thread[0]->getInstAsid(); }
+    int getDataAsid() { return thread[0]->getDataAsid(); }
 
 #endif
 
@@ -320,16 +321,17 @@ class FullO3CPU : public BaseFullCPU
 
   public:
     /** The temporary exec context to support older accessors. */
-    ExecContext *xc;
+    CPUExecContext *cpuXC;
 
     /** Temporary function to get pointer to exec context. */
     ExecContext *xcBase()
     {
-#if FULL_SYSTEM
-        return system->execContexts[0];
-#else
+        return thread[0]->getProxy();
+    }
+
+    CPUExecContext *cpuXCBase()
+    {
         return thread[0];
-#endif
     }
 
     InstSeqNum globalSeqNum;
@@ -344,9 +346,8 @@ class FullO3CPU : public BaseFullCPU
     AlphaDTB *dtb;
 
 //    SWContext *swCtx;
-#else
-    std::vector<ExecContext *> thread;
 #endif
+    std::vector<CPUExecContext *> thread;
 
     FunctionalMemory *mem;
 
diff --git a/cpu/pc_event.cc b/cpu/pc_event.cc
index 83fbc3e2d..050bf1a88 100644
--- a/cpu/pc_event.cc
+++ b/cpu/pc_event.cc
@@ -38,6 +38,7 @@
 #include "cpu/pc_event.hh"
 #include "sim/debug.hh"
 #include "sim/root.hh"
+#include "sim/system.hh"
 
 using namespace std;
 
@@ -79,7 +80,7 @@ PCEventQueue::schedule(PCEvent *event)
 bool
 PCEventQueue::doService(ExecContext *xc)
 {
-    Addr pc = xc->regs.pc & ~0x3;
+    Addr pc = xc->readPC() & ~0x3;
     int serviced = 0;
     range_t range = equal_range(pc);
     for (iterator i = range.first; i != range.second; ++i) {
@@ -87,7 +88,7 @@ PCEventQueue::doService(ExecContext *xc)
         // another event.  This for example, prevents two invocations
         // of the SkipFuncEvent.  Maybe we should have separate PC
         // event queues for each processor?
-        if (pc != (xc->regs.pc & ~0x3))
+        if (pc != (xc->readPC() & ~0x3))
             continue;
 
         DPRINTF(PCEvent, "PC based event serviced at %#x: %s\n",
@@ -126,7 +127,7 @@ BreakPCEvent::BreakPCEvent(PCEventQueue *q, const std::string &desc, Addr addr,
 void
 BreakPCEvent::process(ExecContext *xc)
 {
-    StringWrap name(xc->cpu->name() + ".break_event");
+    StringWrap name(xc->getCpuPtr()->name() + ".break_event");
     DPRINTFN("break event %s triggered\n", descr());
     debug_break();
     if (remove)
diff --git a/cpu/simple/cpu.cc b/cpu/simple/cpu.cc
index dd2d53c17..7c60b242f 100644
--- a/cpu/simple/cpu.cc
+++ b/cpu/simple/cpu.cc
@@ -44,6 +44,7 @@
 #include "base/stats/events.hh"
 #include "base/trace.hh"
 #include "cpu/base.hh"
+#include "cpu/cpu_exec_context.hh"
 #include "cpu/exec_context.hh"
 #include "cpu/exetrace.hh"
 #include "cpu/profile.hh"
@@ -94,7 +95,7 @@ SimpleCPU::init()
         ExecContext *xc = execContexts[i];
 
         // initialize CPU, including PC
-        TheISA::initCPU(&xc->regs, xc->cpu_id);
+        TheISA::initCPU(xc, xc->readCpuId());
     }
 #endif
 }
@@ -132,22 +133,24 @@ SimpleCPU::CacheCompletionEvent::description()
 }
 
 SimpleCPU::SimpleCPU(Params *p)
-    : BaseCPU(p), tickEvent(this, p->width), xc(NULL),
+    : BaseCPU(p), tickEvent(this, p->width), cpuXC(NULL),
       cacheCompletionEvent(this)
 {
     _status = Idle;
 #if FULL_SYSTEM
-    xc = new ExecContext(this, 0, p->system, p->itb, p->dtb, p->mem);
+    cpuXC = new CPUExecContext(this, 0, p->system, p->itb, p->dtb, p->mem);
 
 #else
-    xc = new ExecContext(this, /* thread_num */ 0, p->process, /* asid */ 0);
+    cpuXC = new CPUExecContext(this, /* thread_num */ 0, p->process,
+                               /* asid */ 0);
 #endif // !FULL_SYSTEM
+    xcProxy = cpuXC->getProxy();
 
     icacheInterface = p->icache_interface;
     dcacheInterface = p->dcache_interface;
 
     memReq = new MemReq();
-    memReq->xc = xc;
+    memReq->xc = xcProxy;
     memReq->asid = 0;
     memReq->data = new uint8_t[64];
 
@@ -158,7 +161,7 @@ SimpleCPU::SimpleCPU(Params *p)
     lastIcacheStall = 0;
     lastDcacheStall = 0;
 
-    execContexts.push_back(xc);
+    execContexts.push_back(xcProxy);
 }
 
 SimpleCPU::~SimpleCPU()
@@ -207,7 +210,7 @@ void
 SimpleCPU::activateContext(int thread_num, int delay)
 {
     assert(thread_num == 0);
-    assert(xc);
+    assert(cpuXC);
 
     assert(_status == Idle);
     notIdleFraction++;
@@ -220,7 +223,7 @@ void
 SimpleCPU::suspendContext(int thread_num)
 {
     assert(thread_num == 0);
-    assert(xc);
+    assert(cpuXC);
 
     assert(_status == Running);
     notIdleFraction--;
@@ -301,7 +304,7 @@ SimpleCPU::serialize(ostream &os)
     SERIALIZE_ENUM(_status);
     SERIALIZE_SCALAR(inst);
     nameOut(os, csprintf("%s.xc", name()));
-    xc->serialize(os);
+    cpuXC->serialize(os);
     nameOut(os, csprintf("%s.tickEvent", name()));
     tickEvent.serialize(os);
     nameOut(os, csprintf("%s.cacheCompletionEvent", name()));
@@ -314,7 +317,7 @@ SimpleCPU::unserialize(Checkpoint *cp, const string &section)
     BaseCPU::unserialize(cp, section);
     UNSERIALIZE_ENUM(_status);
     UNSERIALIZE_SCALAR(inst);
-    xc->unserialize(cp, csprintf("%s.xc", section));
+    cpuXC->unserialize(cp, csprintf("%s.xc", section));
     tickEvent.unserialize(cp, csprintf("%s.tickEvent", section));
     cacheCompletionEvent
         .unserialize(cp, csprintf("%s.cacheCompletionEvent", section));
@@ -345,16 +348,16 @@ SimpleCPU::copySrcTranslate(Addr src)
     memReq->reset(src & ~(blk_size - 1), blk_size);
 
     // translate to physical address
-    Fault fault = xc->translateDataReadReq(memReq);
+    Fault fault = cpuXC->translateDataReadReq(memReq);
 
     assert(fault != AlignmentFault);
 
     if (fault == NoFault) {
-        xc->copySrcAddr = src;
-        xc->copySrcPhysAddr = memReq->paddr + offset;
+        cpuXC->copySrcAddr = src;
+        cpuXC->copySrcPhysAddr = memReq->paddr + offset;
     } else {
-        xc->copySrcAddr = 0;
-        xc->copySrcPhysAddr = 0;
+        cpuXC->copySrcAddr = 0;
+        cpuXC->copySrcPhysAddr = 0;
     }
     return fault;
 }
@@ -367,7 +370,7 @@ SimpleCPU::copy(Addr dest)
     // Only support block sizes of 64 atm.
     assert(blk_size == 64);
     uint8_t data[blk_size];
-    //assert(xc->copySrcAddr);
+    //assert(cpuXC->copySrcAddr);
     int offset = dest & (blk_size - 1);
 
     // Make sure block doesn't span page
@@ -380,21 +383,21 @@ SimpleCPU::copy(Addr dest)
 
     memReq->reset(dest & ~(blk_size -1), blk_size);
     // translate to physical address
-    Fault fault = xc->translateDataWriteReq(memReq);
+    Fault fault = cpuXC->translateDataWriteReq(memReq);
 
     assert(fault != AlignmentFault);
 
     if (fault == NoFault) {
         Addr dest_addr = memReq->paddr + offset;
         // Need to read straight from memory since we have more than 8 bytes.
-        memReq->paddr = xc->copySrcPhysAddr;
-        xc->mem->read(memReq, data);
+        memReq->paddr = cpuXC->copySrcPhysAddr;
+        cpuXC->mem->read(memReq, data);
         memReq->paddr = dest_addr;
-        xc->mem->write(memReq, data);
+        cpuXC->mem->write(memReq, data);
         if (dcacheInterface) {
             memReq->cmd = Copy;
             memReq->completionEvent = NULL;
-            memReq->paddr = xc->copySrcPhysAddr;
+            memReq->paddr = cpuXC->copySrcPhysAddr;
             memReq->dest = dest_addr;
             memReq->size = 64;
             memReq->time = curTick;
@@ -411,7 +414,7 @@ Fault
 SimpleCPU::read(Addr addr, T &data, unsigned flags)
 {
     if (status() == DcacheMissStall || status() == DcacheMissSwitch) {
-        Fault fault = xc->read(memReq,data);
+        Fault fault = cpuXC->read(memReq,data);
 
         if (traceData) {
             traceData->setAddr(addr);
@@ -422,7 +425,7 @@ SimpleCPU::read(Addr addr, T &data, unsigned flags)
     memReq->reset(addr, sizeof(T), flags);
 
     // translate to physical address
-    Fault fault = xc->translateDataReadReq(memReq);
+    Fault fault = cpuXC->translateDataReadReq(memReq);
 
     // if we have a cache, do cache access too
     if (fault == NoFault && dcacheInterface) {
@@ -442,12 +445,12 @@ SimpleCPU::read(Addr addr, T &data, unsigned flags)
             _status = DcacheMissStall;
         } else {
             // do functional access
-            fault = xc->read(memReq, data);
+            fault = cpuXC->read(memReq, data);
 
         }
     } else if(fault == NoFault) {
         // do functional access
-        fault = xc->read(memReq, data);
+        fault = cpuXC->read(memReq, data);
 
     }
 
@@ -507,11 +510,11 @@ SimpleCPU::write(T data, Addr addr, unsigned flags, uint64_t *res)
     memReq->reset(addr, sizeof(T), flags);
 
     // translate to physical address
-    Fault fault = xc->translateDataWriteReq(memReq);
+    Fault fault = cpuXC->translateDataWriteReq(memReq);
 
     // do functional access
     if (fault == NoFault)
-        fault = xc->write(memReq, data);
+        fault = cpuXC->write(memReq, data);
 
     if (fault == NoFault && dcacheInterface) {
         memReq->cmd = Write;
@@ -588,7 +591,7 @@ SimpleCPU::write(int32_t data, Addr addr, unsigned flags, uint64_t *res)
 Addr
 SimpleCPU::dbg_vtophys(Addr addr)
 {
-    return vtophys(xc, addr);
+    return vtophys(xcProxy, addr);
 }
 #endif // FULL_SYSTEM
 
@@ -636,9 +639,9 @@ SimpleCPU::post_interrupt(int int_num, int index)
 {
     BaseCPU::post_interrupt(int_num, index);
 
-    if (xc->status() == ExecContext::Suspended) {
+    if (cpuXC->status() == ExecContext::Suspended) {
                 DPRINTF(IPI,"Suspended Processor awoke\n");
-        xc->activate();
+        cpuXC->activate();
     }
 }
 #endif // FULL_SYSTEM
@@ -654,16 +657,16 @@ SimpleCPU::tick()
     Fault fault = NoFault;
 
 #if FULL_SYSTEM
-    if (checkInterrupts && check_interrupts() && !xc->inPalMode() &&
+    if (checkInterrupts && check_interrupts() && !cpuXC->inPalMode() &&
         status() != IcacheMissComplete) {
         int ipl = 0;
         int summary = 0;
         checkInterrupts = false;
 
-        if (xc->readMiscReg(IPR_SIRR)) {
+        if (cpuXC->readMiscReg(IPR_SIRR)) {
             for (int i = INTLEVEL_SOFTWARE_MIN;
                  i < INTLEVEL_SOFTWARE_MAX; i++) {
-                if (xc->readMiscReg(IPR_SIRR) & (ULL(1) << i)) {
+                if (cpuXC->readMiscReg(IPR_SIRR) & (ULL(1) << i)) {
                     // See table 4-19 of 21164 hardware reference
                     ipl = (i - INTLEVEL_SOFTWARE_MIN) + 1;
                     summary |= (ULL(1) << i);
@@ -671,7 +674,7 @@ SimpleCPU::tick()
             }
         }
 
-        uint64_t interrupts = xc->cpu->intr_status();
+        uint64_t interrupts = cpuXC->cpu->intr_status();
         for (int i = INTLEVEL_EXTERNAL_MIN;
             i < INTLEVEL_EXTERNAL_MAX; i++) {
             if (interrupts & (ULL(1) << i)) {
@@ -681,24 +684,24 @@ SimpleCPU::tick()
             }
         }
 
-        if (xc->readMiscReg(IPR_ASTRR))
+        if (cpuXC->readMiscReg(IPR_ASTRR))
             panic("asynchronous traps not implemented\n");
 
-        if (ipl && ipl > xc->readMiscReg(IPR_IPLR)) {
-            xc->setMiscReg(IPR_ISR, summary);
-            xc->setMiscReg(IPR_INTID, ipl);
-            xc->ev5_trap(InterruptFault);
+        if (ipl && ipl > cpuXC->readMiscReg(IPR_IPLR)) {
+            cpuXC->setMiscReg(IPR_ISR, summary);
+            cpuXC->setMiscReg(IPR_INTID, ipl);
+            cpuXC->ev5_trap(InterruptFault);
 
             DPRINTF(Flow, "Interrupt! IPLR=%d ipl=%d summary=%x\n",
-                    xc->readMiscReg(IPR_IPLR), ipl, summary);
+                    cpuXC->readMiscReg(IPR_IPLR), ipl, summary);
         }
     }
 #endif
 
     // maintain $r0 semantics
-    xc->regs.intRegFile[ZeroReg] = 0;
+    cpuXC->setIntReg(ZeroReg, 0);
 #ifdef TARGET_ALPHA
-    xc->regs.floatRegFile.d[ZeroReg] = 0.0;
+    cpuXC->setFloatRegDouble(ZeroReg, 0.0);
 #endif // TARGET_ALPHA
 
     if (status() == IcacheMissComplete) {
@@ -720,13 +723,13 @@ SimpleCPU::tick()
 #endif
 
         memReq->cmd = Read;
-        memReq->reset(xc->regs.pc & ~3, sizeof(uint32_t),
-                     IFETCH_FLAGS(xc->regs.pc));
+        memReq->reset(cpuXC->readPC() & ~3, sizeof(uint32_t),
+                     IFETCH_FLAGS(cpuXC->readPC()));
 
-        fault = xc->translateInstReq(memReq);
+        fault = cpuXC->translateInstReq(memReq);
 
         if (fault == NoFault)
-            fault = xc->mem->read(memReq, inst);
+            fault = cpuXC->mem->read(memReq, inst);
 
         if (icacheInterface && fault == NoFault) {
             memReq->completionEvent = NULL;
@@ -763,29 +766,30 @@ SimpleCPU::tick()
         inst = gtoh(inst);
         curStaticInst = StaticInst::decode(inst);
 
-        traceData = Trace::getInstRecord(curTick, xc, this, curStaticInst,
-                                         xc->regs.pc);
+        traceData = Trace::getInstRecord(curTick, xcProxy, this, curStaticInst,
+                                         cpuXC->readPC());
 
 #if FULL_SYSTEM
-        xc->setInst(inst);
+        cpuXC->setInst(inst);
 #endif // FULL_SYSTEM
 
-        xc->func_exe_inst++;
+        cpuXC->func_exe_inst++;
 
         fault = curStaticInst->execute(this, traceData);
 
 #if FULL_SYSTEM
-        if (xc->fnbin) {
-            assert(xc->kernelStats);
-            system->kernelBinning->execute(xc, inst);
+        if (system->kernelBinning->fnbin) {
+            assert(kernelStats);
+            system->kernelBinning->execute(xcProxy, inst);
         }
 
-        if (xc->profile) {
-            bool usermode = (xc->readMiscReg(AlphaISA::IPR_DTB_CM) & 0x18) != 0;
-            xc->profilePC = usermode ? 1 : xc->regs.pc;
-            ProfileNode *node = xc->profile->consume(xc, inst);
+        if (cpuXC->profile) {
+            bool usermode =
+                (cpuXC->readMiscReg(AlphaISA::IPR_DTB_CM) & 0x18) != 0;
+            cpuXC->profilePC = usermode ? 1 : cpuXC->readPC();
+            ProfileNode *node = cpuXC->profile->consume(xcProxy, inst);
             if (node)
-                xc->profileNode = node;
+                cpuXC->profileNode = node;
         }
 #endif
 
@@ -805,29 +809,29 @@ SimpleCPU::tick()
             traceData->finalize();
         }
 
-        traceFunctions(xc->regs.pc);
+        traceFunctions(cpuXC->readPC());
 
     }	// if (fault == NoFault)
 
     if (fault != NoFault) {
 #if FULL_SYSTEM
-        xc->ev5_trap(fault);
+        cpuXC->ev5_trap(fault);
 #else // !FULL_SYSTEM
-        fatal("fault (%d) detected @ PC 0x%08p", fault, xc->regs.pc);
+        fatal("fault (%d) detected @ PC 0x%08p", fault, cpuXC->readPC());
 #endif // FULL_SYSTEM
     }
     else {
         // go to the next instruction
-        xc->regs.pc = xc->regs.npc;
-        xc->regs.npc += sizeof(MachInst);
+        cpuXC->setPC(cpuXC->readNextPC());
+        cpuXC->setNextPC(cpuXC->readNextPC() + sizeof(MachInst));
     }
 
 #if FULL_SYSTEM
     Addr oldpc;
     do {
-        oldpc = xc->regs.pc;
-        system->pcEventQueue.service(xc);
-    } while (oldpc != xc->regs.pc);
+        oldpc = cpuXC->readPC();
+        system->pcEventQueue.service(xcProxy);
+    } while (oldpc != cpuXC->readPC());
 #endif
 
     assert(status() == Running ||
diff --git a/cpu/simple/cpu.hh b/cpu/simple/cpu.hh
index 3bc905be1..1441a8fcd 100644
--- a/cpu/simple/cpu.hh
+++ b/cpu/simple/cpu.hh
@@ -32,7 +32,7 @@
 #include "base/statistics.hh"
 #include "config/full_system.hh"
 #include "cpu/base.hh"
-#include "cpu/exec_context.hh"
+#include "cpu/cpu_exec_context.hh"
 #include "cpu/pc_event.hh"
 #include "cpu/sampler/sampler.hh"
 #include "cpu/static_inst.hh"
@@ -54,6 +54,7 @@ class Process;
 
 #endif // FULL_SYSTEM
 
+class ExecContext;
 class MemInterface;
 class Checkpoint;
 
@@ -148,7 +149,9 @@ class SimpleCPU : public BaseCPU
 
   public:
     // execution context
-    ExecContext *xc;
+    CPUExecContext *cpuXC;
+
+    ExecContext *xcProxy;
 
     void switchOut(Sampler *s);
     void takeOverFrom(BaseCPU *oldCPU);
@@ -275,86 +278,86 @@ class SimpleCPU : public BaseCPU
 
     uint64_t readIntReg(const StaticInst *si, int idx)
     {
-        return xc->readIntReg(si->srcRegIdx(idx));
+        return cpuXC->readIntReg(si->srcRegIdx(idx));
     }
 
     float readFloatRegSingle(const StaticInst *si, int idx)
     {
         int reg_idx = si->srcRegIdx(idx) - TheISA::FP_Base_DepTag;
-        return xc->readFloatRegSingle(reg_idx);
+        return cpuXC->readFloatRegSingle(reg_idx);
     }
 
     double readFloatRegDouble(const StaticInst *si, int idx)
     {
         int reg_idx = si->srcRegIdx(idx) - TheISA::FP_Base_DepTag;
-        return xc->readFloatRegDouble(reg_idx);
+        return cpuXC->readFloatRegDouble(reg_idx);
     }
 
     uint64_t readFloatRegInt(const StaticInst *si, int idx)
     {
         int reg_idx = si->srcRegIdx(idx) - TheISA::FP_Base_DepTag;
-        return xc->readFloatRegInt(reg_idx);
+        return cpuXC->readFloatRegInt(reg_idx);
     }
 
     void setIntReg(const StaticInst *si, int idx, uint64_t val)
     {
-        xc->setIntReg(si->destRegIdx(idx), val);
+        cpuXC->setIntReg(si->destRegIdx(idx), val);
     }
 
     void setFloatRegSingle(const StaticInst *si, int idx, float val)
     {
         int reg_idx = si->destRegIdx(idx) - TheISA::FP_Base_DepTag;
-        xc->setFloatRegSingle(reg_idx, val);
+        cpuXC->setFloatRegSingle(reg_idx, val);
     }
 
     void setFloatRegDouble(const StaticInst *si, int idx, double val)
     {
         int reg_idx = si->destRegIdx(idx) - TheISA::FP_Base_DepTag;
-        xc->setFloatRegDouble(reg_idx, val);
+        cpuXC->setFloatRegDouble(reg_idx, val);
     }
 
     void setFloatRegInt(const StaticInst *si, int idx, uint64_t val)
     {
         int reg_idx = si->destRegIdx(idx) - TheISA::FP_Base_DepTag;
-        xc->setFloatRegInt(reg_idx, val);
+        cpuXC->setFloatRegInt(reg_idx, val);
     }
 
-    uint64_t readPC() { return xc->readPC(); }
-    void setNextPC(uint64_t val) { xc->setNextPC(val); }
+    uint64_t readPC() { return cpuXC->readPC(); }
+    void setNextPC(uint64_t val) { cpuXC->setNextPC(val); }
 
     MiscReg readMiscReg(int misc_reg)
     {
-        return xc->readMiscReg(misc_reg);
+        return cpuXC->readMiscReg(misc_reg);
     }
 
     MiscReg readMiscRegWithEffect(int misc_reg, Fault &fault)
     {
-        return xc->readMiscRegWithEffect(misc_reg, fault);
+        return cpuXC->readMiscRegWithEffect(misc_reg, fault);
     }
 
     Fault setMiscReg(int misc_reg, const MiscReg &val)
     {
-        return xc->setMiscReg(misc_reg, val);
+        return cpuXC->setMiscReg(misc_reg, val);
     }
 
     Fault setMiscRegWithEffect(int misc_reg, const MiscReg &val)
     {
-        return xc->setMiscRegWithEffect(misc_reg, val);
+        return cpuXC->setMiscRegWithEffect(misc_reg, val);
     }
 
 #if FULL_SYSTEM
-    Fault hwrei() { return xc->hwrei(); }
-    int readIntrFlag() { return xc->readIntrFlag(); }
-    void setIntrFlag(int val) { xc->setIntrFlag(val); }
-    bool inPalMode() { return xc->inPalMode(); }
-    void ev5_trap(Fault fault) { xc->ev5_trap(fault); }
-    bool simPalCheck(int palFunc) { return xc->simPalCheck(palFunc); }
+    Fault hwrei() { return cpuXC->hwrei(); }
+    int readIntrFlag() { return cpuXC->readIntrFlag(); }
+    void setIntrFlag(int val) { cpuXC->setIntrFlag(val); }
+    bool inPalMode() { return cpuXC->inPalMode(); }
+    void ev5_trap(Fault fault) { cpuXC->ev5_trap(fault); }
+    bool simPalCheck(int palFunc) { return cpuXC->simPalCheck(palFunc); }
 #else
-    void syscall() { xc->syscall(); }
+    void syscall() { cpuXC->syscall(); }
 #endif
 
-    bool misspeculating() { return xc->misspeculating(); }
-    ExecContext *xcBase() { return xc; }
+    bool misspeculating() { return cpuXC->misspeculating(); }
+    ExecContext *xcBase() { return xcProxy; }
 };
 
 #endif // __CPU_SIMPLE_CPU_SIMPLE_CPU_HH__