diff -r 7639c17357dc -r 7503f280a9df configs/ruby/Ruby.py
--- a/configs/ruby/Ruby.py	Tue Feb 03 14:26:02 2015 -0500
+++ b/configs/ruby/Ruby.py	Tue Feb 10 10:11:16 2015 -0600
@@ -235,7 +235,8 @@
 
     # Create a backing copy of physical memory in case required
     if options.access_backing_store:
-        ruby.phys_mem = SimpleMemory(range=AddrRange(options.mem_size),
+        ruby.access_backing_store = True
+        ruby.phys_mem = SimpleMemory(range=system.mem_ranges[0],
                                      in_addr_map=False)
 
 def send_evicts(options):
diff -r 7639c17357dc -r 7503f280a9df src/mem/ruby/system/DMASequencer.hh
--- a/src/mem/ruby/system/DMASequencer.hh	Tue Feb 03 14:26:02 2015 -0500
+++ b/src/mem/ruby/system/DMASequencer.hh	Tue Feb 10 10:11:16 2015 -0600
@@ -29,8 +29,8 @@
 #ifndef __MEM_RUBY_SYSTEM_DMASEQUENCER_HH__
 #define __MEM_RUBY_SYSTEM_DMASEQUENCER_HH__
 
+#include <memory>
 #include <ostream>
-#include <memory>
 
 #include "mem/protocol/DMASequencerRequestType.hh"
 #include "mem/protocol/RequestStatus.hh"
@@ -38,6 +38,7 @@
 #include "mem/ruby/network/MessageBuffer.hh"
 #include "mem/ruby/system/System.hh"
 #include "mem/mem_object.hh"
+#include "mem/simple_mem.hh"
 #include "mem/tport.hh"
 #include "params/DMASequencer.hh"
 
@@ -66,10 +67,13 @@
     {
       private:
         SlavePacketQueue queue;
+        RubySystem* ruby_system;
+        bool access_backing_store;
 
       public:
         MemSlavePort(const std::string &_name, DMASequencer *_port,
-                     PortID id);
+                     PortID id, RubySystem *_ruby_system,
+                     bool _access_backing_store);
         void hitCallback(PacketPtr pkt);
         void evictionCallback(const Address& address);
 
diff -r 7639c17357dc -r 7503f280a9df src/mem/ruby/system/DMASequencer.cc
--- a/src/mem/ruby/system/DMASequencer.cc	Tue Feb 03 14:26:02 2015 -0500
+++ b/src/mem/ruby/system/DMASequencer.cc	Tue Feb 10 10:11:16 2015 -0600
@@ -40,7 +40,8 @@
 DMASequencer::DMASequencer(const Params *p)
     : MemObject(p), m_version(p->version), m_controller(NULL),
       m_mandatory_q_ptr(NULL), m_usingRubyTester(p->using_ruby_tester),
-      slave_port(csprintf("%s.slave", name()), this, 0),
+      slave_port(csprintf("%s.slave", name()), this, 0, p->ruby_system,
+                 p->ruby_system->getAccessBackingStore()),
       drainManager(NULL), system(p->system), retry(false)
 {
     assert(m_version != -1);
@@ -73,8 +74,10 @@
 }
 
 DMASequencer::MemSlavePort::MemSlavePort(const std::string &_name,
-    DMASequencer *_port, PortID id)
-    : QueuedSlavePort(_name, _port, queue, id), queue(*_port, *this)
+    DMASequencer *_port, PortID id, RubySystem* _ruby_system,
+    bool _access_backing_store)
+    : QueuedSlavePort(_name, _port, queue, id), queue(*_port, *this),
+      ruby_system(_ruby_system), access_backing_store(_access_backing_store)
 {
     DPRINTF(RubyDma, "Created slave memport on ruby sequencer %s\n", _name);
 }
@@ -208,8 +211,14 @@
     DPRINTF(RubyDma, "Hit callback needs response %d\n", needsResponse);
 
     // turn packet around to go back to requester if response expected
+
+    if (access_backing_store) {
+        ruby_system->getPhysMem()->access(pkt);
+    } else if (needsResponse) {
+        pkt->makeResponse();
+    }
+
     if (needsResponse) {
-        pkt->makeResponse();
         DPRINTF(RubyDma, "Sending packet back over port\n");
         // send next cycle
         schedTimingResp(pkt, curTick() + g_system_ptr->clockPeriod());
diff -r 7639c17357dc -r 7503f280a9df src/mem/ruby/system/RubyPort.cc
--- a/src/mem/ruby/system/RubyPort.cc	Tue Feb 03 14:26:02 2015 -0500
+++ b/src/mem/ruby/system/RubyPort.cc	Tue Feb 10 10:11:16 2015 -0600
@@ -58,7 +58,7 @@
       pioSlavePort(csprintf("%s.pio-slave-port", name()), this),
       memMasterPort(csprintf("%s.mem-master-port", name()), this),
       memSlavePort(csprintf("%s-mem-slave-port", name()), this,
-          p->ruby_system, p->access_backing_store, -1),
+          p->ruby_system, p->ruby_system->getAccessBackingStore(), -1),
       gotAddrRanges(p->port_master_connection_count), drainManager(NULL)
 {
     assert(m_version != -1);
@@ -66,7 +66,8 @@
     // create the slave ports based on the number of connected ports
     for (size_t i = 0; i < p->port_slave_connection_count; ++i) {
         slave_ports.push_back(new MemSlavePort(csprintf("%s.slave%d", name(),
-            i), this, p->ruby_system, p->access_backing_store, i));
+            i), this, p->ruby_system,
+            p->ruby_system->getAccessBackingStore(), i));
     }
 
     // create the master ports based on the number of connected ports
@@ -297,40 +298,40 @@
                 line_address(Address(pkt->getAddr())).getAddress() +
                 RubySystem::getBlockSizeBytes());
 
-    bool accessSucceeded = false;
-    bool needsResponse = pkt->needsResponse();
-
-    // Do the functional access on ruby memory
-    if (pkt->isRead()) {
-        accessSucceeded = ruby_system->functionalRead(pkt);
-    } else if (pkt->isWrite()) {
-        accessSucceeded = ruby_system->functionalWrite(pkt);
-    } else {
-        panic("Unsupported functional command %s\n", pkt->cmdString());
-    }
-
-    // Unless the requester explicitly said otherwise, generate an error if
-    // the functional request failed
-    if (!accessSucceeded && !pkt->suppressFuncError()) {
-        fatal("Ruby functional %s failed for address %#x\n",
-              pkt->isWrite() ? "write" : "read", pkt->getAddr());
-    }
-
     if (access_backing_store) {
         // The attached physmem contains the official version of data.
         // The following command performs the real functional access.
         // This line should be removed once Ruby supplies the official version
         // of data.
         ruby_system->getPhysMem()->functionalAccess(pkt);
+    } else {
+        bool accessSucceeded = false;
+        bool needsResponse = pkt->needsResponse();
+
+        // Do the functional access on ruby memory
+        if (pkt->isRead()) {
+            accessSucceeded = ruby_system->functionalRead(pkt);
+        } else if (pkt->isWrite()) {
+            accessSucceeded = ruby_system->functionalWrite(pkt);
+        } else {
+            panic("Unsupported functional command %s\n", pkt->cmdString());
+        }
+
+        // Unless the requester explicitly said otherwise, generate an error if
+        // the functional request failed
+        if (!accessSucceeded && !pkt->suppressFuncError()) {
+            fatal("Ruby functional %s failed for address %#x\n",
+                  pkt->isWrite() ? "write" : "read", pkt->getAddr());
+        }
+
+        // turn packet around to go back to requester if response expected
+        if (needsResponse) {
+            pkt->setFunctionalResponseStatus(accessSucceeded);
+        }
+
+        DPRINTF(RubyPort, "Functional access %s!\n",
+                accessSucceeded ? "successful":"failed");
     }
-
-    // turn packet around to go back to requester if response expected
-    if (needsResponse) {
-        pkt->setFunctionalResponseStatus(accessSucceeded);
-    }
-
-    DPRINTF(RubyPort, "Functional access %s!\n",
-            accessSucceeded ? "successful":"failed");
 }
 
 void
@@ -495,7 +496,7 @@
     DPRINTF(RubyPort, "Hit callback needs response %d\n", needsResponse);
 
     if (accessPhysMem) {
-        ruby_system->getPhysMem()->functionalAccess(pkt);
+        ruby_system->getPhysMem()->access(pkt);
     } else if (needsResponse) {
         pkt->makeResponse();
     }
diff -r 7639c17357dc -r 7503f280a9df src/mem/ruby/system/RubySystem.py
--- a/src/mem/ruby/system/RubySystem.py	Tue Feb 03 14:26:02 2015 -0500
+++ b/src/mem/ruby/system/RubySystem.py	Tue Feb 10 10:11:16 2015 -0600
@@ -47,3 +47,6 @@
     all_instructions = Param.Bool(False, "")
     num_of_sequencers = Param.Int("")
     phys_mem = Param.SimpleMemory(NULL, "")
+
+    access_backing_store = Param.Bool(False, "Use phys_mem as the functional \
+        store and only use ruby for timing.")
diff -r 7639c17357dc -r 7503f280a9df src/mem/ruby/system/Sequencer.py
--- a/src/mem/ruby/system/Sequencer.py	Tue Feb 03 14:26:02 2015 -0500
+++ b/src/mem/ruby/system/Sequencer.py	Tue Feb 10 10:11:16 2015 -0600
@@ -45,8 +45,6 @@
     mem_slave_port = SlavePort("Ruby memory port")
 
     using_ruby_tester = Param.Bool(False, "")
-    access_backing_store = Param.Bool(False,
-        "should the rubyport atomically update phys_mem")
     ruby_system = Param.RubySystem("")
     system = Param.System(Parent.any, "system object")
     support_data_reqs = Param.Bool(True, "data cache requests supported")
diff -r 7639c17357dc -r 7503f280a9df src/mem/ruby/system/System.hh
--- a/src/mem/ruby/system/System.hh	Tue Feb 03 14:26:02 2015 -0500
+++ b/src/mem/ruby/system/System.hh	Tue Feb 10 10:11:16 2015 -0600
@@ -76,6 +76,7 @@
     static uint32_t getMemorySizeBits() { return m_memory_size_bits; }
 
     SimpleMemory *getPhysMem() { return m_phys_mem; }
+    const bool getAccessBackingStore() { return m_access_backing_store; }
 
     // Public Methods
     Profiler*
@@ -125,6 +126,7 @@
     static uint32_t m_block_size_bits;
     static uint32_t m_memory_size_bits;
     SimpleMemory *m_phys_mem;
+    const bool m_access_backing_store;
 
     Network* m_network;
     std::vector<AbstractController *> m_abs_cntrl_vec;
diff -r 7639c17357dc -r 7503f280a9df src/mem/ruby/system/System.cc
--- a/src/mem/ruby/system/System.cc	Tue Feb 03 14:26:02 2015 -0500
+++ b/src/mem/ruby/system/System.cc	Tue Feb 10 10:11:16 2015 -0600
@@ -38,6 +38,7 @@
 #include "mem/ruby/common/Address.hh"
 #include "mem/ruby/network/Network.hh"
 #include "mem/ruby/system/System.hh"
+#include "mem/simple_mem.hh"
 #include "sim/eventq.hh"
 #include "sim/simulate.hh"
 
@@ -50,7 +51,7 @@
 uint32_t RubySystem::m_memory_size_bits;
 
 RubySystem::RubySystem(const Params *p)
-    : ClockedObject(p)
+    : ClockedObject(p), m_access_backing_store(p->access_backing_store)
 {
     if (g_system_ptr != NULL)
         fatal("Only one RubySystem object currently allowed.\n");