diff -r fc7d56547e33 -r 54a18bf193b4 configs/common/Options.py
--- a/configs/common/Options.py	Fri May 24 11:25:10 2013 +0100
+++ b/configs/common/Options.py	Fri May 24 11:35:05 2013 +0100
@@ -78,6 +78,10 @@
     parser.add_option("--simpoint-interval", type="int", default=10000000,
                       help="SimPoint interval in num of instructions")
     parser.add_option("--clock", action="store", type="string", default='2GHz')
+    parser.add_option("--sys-clock", action="store", type="string",
+                      default='1GHz',
+                      help = """Top-level clock for blocks running at system
+                      speed""")
     parser.add_option("--cpu-clock", action="store", type="string",
                       default='2GHz',
                       help="Clock for blocks running at CPU speed")
diff -r fc7d56547e33 -r 54a18bf193b4 configs/example/fs.py
--- a/configs/example/fs.py	Fri May 24 11:25:10 2013 +0100
+++ b/configs/example/fs.py	Fri May 24 11:35:05 2013 +0100
@@ -120,6 +120,8 @@
 else:
     fatal("Incapable of building %s full system!", buildEnv['TARGET_ISA'])
 
+test_sys.clock = options.sys_clock
+
 if options.kernel is not None:
     test_sys.kernel = binary(options.kernel)
 
@@ -172,6 +174,8 @@
         drive_sys = makeArmSystem(drive_mem_mode, options.machine_type,
                                   DriveMemClass, bm[1])
 
+    drive_sys.clock = options.sys_clock
+
     drive_sys.cpu = DriveCPUClass(cpu_id=0)
     drive_sys.cpu.createThreads()
     drive_sys.cpu.createInterruptController()
diff -r fc7d56547e33 -r 54a18bf193b4 configs/example/memtest.py
--- a/configs/example/memtest.py	Fri May 24 11:25:10 2013 +0100
+++ b/configs/example/memtest.py	Fri May 24 11:35:05 2013 +0100
@@ -144,6 +144,7 @@
 system = System(funcmem = SimpleMemory(in_addr_map = False),
                 funcbus = NoncoherentBus(),
                 physmem = SimpleMemory(latency = "100ns"))
+system.clock = options.sys_clock
 
 def make_level(spec, prototypes, attach_obj, attach_port):
      fanout = spec[0]
diff -r fc7d56547e33 -r 54a18bf193b4 configs/example/ruby_direct_test.py
--- a/configs/example/ruby_direct_test.py	Fri May 24 11:25:10 2013 +0100
+++ b/configs/example/ruby_direct_test.py	Fri May 24 11:35:05 2013 +0100
@@ -93,7 +93,7 @@
 # M5 memory size == Ruby memory size checks
 #
 system = System(physmem = SimpleMemory())
-
+system.clock = options.sys_clock
 #
 # Create the ruby random tester
 #
diff -r fc7d56547e33 -r 54a18bf193b4 configs/example/ruby_fs.py
--- a/configs/example/ruby_fs.py	Fri May 24 11:25:10 2013 +0100
+++ b/configs/example/ruby_fs.py	Fri May 24 11:35:05 2013 +0100
@@ -105,6 +105,8 @@
 else:
     fatal("incapable of building non-alpha or non-x86 full system!")
 
+system.clock = options.sys_clock
+
 if options.kernel is not None:
     system.kernel = binary(options.kernel)
 
diff -r fc7d56547e33 -r 54a18bf193b4 configs/example/ruby_mem_test.py
--- a/configs/example/ruby_mem_test.py	Fri May 24 11:25:10 2013 +0100
+++ b/configs/example/ruby_mem_test.py	Fri May 24 11:35:05 2013 +0100
@@ -108,6 +108,7 @@
                 funcmem = SimpleMemory(in_addr_map = False),
                 funcbus = NoncoherentBus(),
                 physmem = SimpleMemory())
+system.clock = options.sys_clock
 
 if options.num_dmas > 0:
     dmas = [ MemTest(atomic = False,
diff -r fc7d56547e33 -r 54a18bf193b4 configs/example/ruby_network_test.py
--- a/configs/example/ruby_network_test.py	Fri May 24 11:25:10 2013 +0100
+++ b/configs/example/ruby_network_test.py	Fri May 24 11:35:05 2013 +0100
@@ -105,6 +105,7 @@
 # create the desired simulated system
 system = System(cpu = cpus,
                 physmem = SimpleMemory())
+system.clock = options.sys_clock
 
 Ruby.create_system(options, system)
 
diff -r fc7d56547e33 -r 54a18bf193b4 configs/example/ruby_random_test.py
--- a/configs/example/ruby_random_test.py	Fri May 24 11:25:10 2013 +0100
+++ b/configs/example/ruby_random_test.py	Fri May 24 11:35:05 2013 +0100
@@ -98,6 +98,7 @@
 # M5 memory size == Ruby memory size checks
 #
 system = System(tester = tester, physmem = SimpleMemory())
+system.clock = options.sys_clock
 
 Ruby.create_system(options, system)
 
diff -r fc7d56547e33 -r 54a18bf193b4 configs/example/se.py
--- a/configs/example/se.py	Fri May 24 11:25:10 2013 +0100
+++ b/configs/example/se.py	Fri May 24 11:35:05 2013 +0100
@@ -160,6 +160,7 @@
 system = System(cpu = [CPUClass(cpu_id=i) for i in xrange(np)],
                 physmem = MemClass(range=AddrRange("512MB")),
                 membus = CoherentBus(), mem_mode = test_mem_mode)
+system.clock = options.sys_clock
 
 # Sanity check
 if options.fastmem:
diff -r fc7d56547e33 -r 54a18bf193b4 configs/splash2/cluster.py
--- a/configs/splash2/cluster.py	Fri May 24 11:25:10 2013 +0100
+++ b/configs/splash2/cluster.py	Fri May 24 11:35:05 2013 +0100
@@ -214,6 +214,7 @@
 system = System(cpu = all_cpus, l1_ = all_l1s, l1bus_ = all_l1buses,
                 physmem = SimpleMemory(),
                 membus = CoherentBus(clock = busFrequency))
+system.clock = '1GHz'
 
 system.toL2bus = CoherentBus(clock = busFrequency)
 system.l2 = L2(size = options.l2size, assoc = 8)
diff -r fc7d56547e33 -r 54a18bf193b4 configs/splash2/run.py
--- a/configs/splash2/run.py	Fri May 24 11:25:10 2013 +0100
+++ b/configs/splash2/run.py	Fri May 24 11:35:05 2013 +0100
@@ -199,6 +199,7 @@
 # ----------------------
 system = System(cpu = cpus, physmem = SimpleMemory(),
                 membus = CoherentBus(clock = busFrequency))
+system.clock = '1GHz'
 
 system.toL2bus = CoherentBus(clock = busFrequency)
 system.l2 = L2(size = options.l2size, assoc = 8)
diff -r fc7d56547e33 -r 54a18bf193b4 src/sim/System.py
--- a/src/sim/System.py	Fri May 24 11:25:10 2013 +0100
+++ b/src/sim/System.py	Fri May 24 11:35:05 2013 +0100
@@ -43,12 +43,6 @@
     cxx_header = "sim/system.hh"
     system_port = MasterPort("System port")
 
-    # Override the clock from the ClockedObject which looks at the
-    # parent clock by default. The 1 GHz default system clock serves
-    # as a start for the modules that rely on the parent to provide
-    # the clock.
-    clock = '1GHz'
-
     @classmethod
     def export_method_cxx_predecls(cls, code):
         code('#include "sim/system.hh"')
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/base_config.py
--- a/tests/configs/base_config.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/base_config.py	Fri May 24 11:35:05 2013 +0100
@@ -131,6 +131,7 @@
         Arguments:
           system -- System to initialize.
         """
+        system.clock = '1GHz'
         system.cpu = self.create_cpus()
 
         if _have_kvm_support and \
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/inorder-timing.py
--- a/tests/configs/inorder-timing.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/inorder-timing.py	Fri May 24 11:35:05 2013 +0100
@@ -42,6 +42,7 @@
                 physmem = DDR3_1600_x64(),
                 membus = CoherentBus(),
                 mem_mode = "timing")
+system.clock = '1GHz'
 system.system_port = system.membus.slave
 system.physmem.port = system.membus.master
 # create the interrupt controller
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/memtest-ruby.py
--- a/tests/configs/memtest-ruby.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/memtest-ruby.py	Fri May 24 11:35:05 2013 +0100
@@ -81,6 +81,7 @@
                 funcmem = SimpleMemory(in_addr_map = False),
                 physmem = SimpleMemory(null = True),
                 funcbus = NoncoherentBus())
+system.clock = options.sys_clock
 
 Ruby.create_system(options, system)
 
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/memtest.py
--- a/tests/configs/memtest.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/memtest.py	Fri May 24 11:35:05 2013 +0100
@@ -40,6 +40,7 @@
                 funcbus = NoncoherentBus(),
                 physmem = SimpleMemory(),
                 membus = CoherentBus(width=16))
+system.clock = '1GHz'
 
 # l2cache & bus
 system.toL2Bus = CoherentBus(clock="2GHz", width=16)
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/o3-timing-checker.py
--- a/tests/configs/o3-timing-checker.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/o3-timing-checker.py	Fri May 24 11:35:05 2013 +0100
@@ -55,6 +55,7 @@
                 physmem = DDR3_1600_x64(),
                 membus = CoherentBus(),
                 mem_mode = "timing")
+system.clock = '1GHz'
 system.system_port = system.membus.slave
 system.physmem.port = system.membus.master
 cpu.connectAllPorts(system.membus)
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/o3-timing-mp-ruby.py
--- a/tests/configs/o3-timing-mp-ruby.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/o3-timing-mp-ruby.py	Fri May 24 11:35:05 2013 +0100
@@ -40,6 +40,7 @@
 # system simulated
 system = System(cpu = cpus, physmem = ruby_memory, membus = CoherentBus(),
                 mem_mode = "timing")
+system.clock = '1GHz'
 
 for cpu in cpus:
     # create the interrupt controller
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/o3-timing-mp.py
--- a/tests/configs/o3-timing-mp.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/o3-timing-mp.py	Fri May 24 11:35:05 2013 +0100
@@ -39,6 +39,7 @@
                 physmem = DDR3_1600_x64(),
                 membus = CoherentBus(),
                 mem_mode = "timing")
+system.clock = '1GHz'
 
 # l2cache & bus
 system.toL2Bus = CoherentBus(clock = '2GHz')
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/o3-timing-ruby.py
--- a/tests/configs/o3-timing-ruby.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/o3-timing-ruby.py	Fri May 24 11:35:05 2013 +0100
@@ -42,6 +42,7 @@
                 physmem = ruby_memory,
                 membus = CoherentBus(),
                 mem_mode = "timing")
+system.clock = '1GHz'
 system.physmem.port = system.membus.master
 # create the interrupt controller
 cpu.createInterruptController()
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/o3-timing.py
--- a/tests/configs/o3-timing.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/o3-timing.py	Fri May 24 11:35:05 2013 +0100
@@ -44,6 +44,7 @@
                 physmem = DDR3_1600_x64(),
                 membus = CoherentBus(),
                 mem_mode = "timing")
+system.clock = '1GHz'
 system.system_port = system.membus.slave
 system.physmem.port = system.membus.master
 # create the interrupt controller
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/rubytest-ruby.py
--- a/tests/configs/rubytest-ruby.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/rubytest-ruby.py	Fri May 24 11:35:05 2013 +0100
@@ -78,6 +78,7 @@
                     wakeup_frequency = 10, num_cpus = options.num_cpus)
 
 system = System(tester = tester, physmem = SimpleMemory(null = True))
+system.clock = options.sys_clock
 
 Ruby.create_system(options, system)
 
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/simple-atomic-dummychecker.py
--- a/tests/configs/simple-atomic-dummychecker.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/simple-atomic-dummychecker.py	Fri May 24 11:35:05 2013 +0100
@@ -41,6 +41,7 @@
 system = System(cpu = AtomicSimpleCPU(cpu_id=0),
                 physmem = SimpleMemory(),
                 membus = CoherentBus())
+system.clock = '1GHz'
 system.system_port = system.membus.slave
 system.physmem.port = system.membus.master
 system.cpu.addCheckerCpu()
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/simple-atomic-mp-ruby.py
--- a/tests/configs/simple-atomic-mp-ruby.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/simple-atomic-mp-ruby.py	Fri May 24 11:35:05 2013 +0100
@@ -39,6 +39,7 @@
 
 # system simulated
 system = System(cpu = cpus, physmem = ruby_memory, membus = CoherentBus())
+system.clock = '1GHz'
 
 # add L1 caches
 for cpu in cpus:
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/simple-atomic-mp.py
--- a/tests/configs/simple-atomic-mp.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/simple-atomic-mp.py	Fri May 24 11:35:05 2013 +0100
@@ -38,7 +38,7 @@
 system = System(cpu = cpus,
                 physmem = SimpleMemory(range = AddrRange('1024MB')),
                 membus = CoherentBus())
-
+system.clock = '1GHz'
 # l2cache & bus
 system.toL2Bus = CoherentBus(clock = '2GHz')
 system.l2c = L2Cache(clock = '2GHz', size='4MB', assoc=8)
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/simple-atomic.py
--- a/tests/configs/simple-atomic.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/simple-atomic.py	Fri May 24 11:35:05 2013 +0100
@@ -32,6 +32,7 @@
 system = System(cpu = AtomicSimpleCPU(cpu_id=0),
                 physmem = SimpleMemory(),
                 membus = CoherentBus())
+system.clock = '1GHz'
 system.system_port = system.membus.slave
 system.physmem.port = system.membus.master
 # create the interrupt controller
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/simple-timing-mp-ruby.py
--- a/tests/configs/simple-timing-mp-ruby.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/simple-timing-mp-ruby.py	Fri May 24 11:35:05 2013 +0100
@@ -72,6 +72,7 @@
 
 # system simulated
 system = System(cpu = cpus, physmem = SimpleMemory())
+system.clock = options.sys_clock
 
 Ruby.create_system(options, system)
 
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/simple-timing-mp.py
--- a/tests/configs/simple-timing-mp.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/simple-timing-mp.py	Fri May 24 11:35:05 2013 +0100
@@ -36,6 +36,7 @@
 
 # system simulated
 system = System(cpu = cpus, physmem = SimpleMemory(), membus = CoherentBus())
+system.clock = '1GHz'
 
 # l2cache & bus
 system.toL2Bus = CoherentBus(clock = '2GHz')
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/simple-timing-ruby.py
--- a/tests/configs/simple-timing-ruby.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/simple-timing-ruby.py	Fri May 24 11:35:05 2013 +0100
@@ -68,6 +68,7 @@
 
 cpu = TimingSimpleCPU(cpu_id=0)
 system = System(cpu = cpu, physmem = SimpleMemory(null = True))
+system.clock = options.sys_clock
 
 Ruby.create_system(options, system)
 
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/simple-timing.py
--- a/tests/configs/simple-timing.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/simple-timing.py	Fri May 24 11:35:05 2013 +0100
@@ -39,6 +39,7 @@
                 physmem = SimpleMemory(),
                 membus = CoherentBus(),
                 mem_mode = "timing")
+system.clock = '1GHz'
 system.system_port = system.membus.slave
 system.physmem.port = system.membus.master
 # create the interrupt controller
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/tgen-simple-dram.py
--- a/tests/configs/tgen-simple-dram.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/tgen-simple-dram.py	Fri May 24 11:35:05 2013 +0100
@@ -50,6 +50,7 @@
 # system simulated
 system = System(cpu = cpu, physmem = DDR3_1600_x64(),
                 membus = NoncoherentBus(width = 16))
+system.clock = '1GHz'
 
 # add a communication monitor
 system.monitor = CommMonitor()
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/tgen-simple-mem.py
--- a/tests/configs/tgen-simple-mem.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/tgen-simple-mem.py	Fri May 24 11:35:05 2013 +0100
@@ -50,6 +50,7 @@
 # system simulated
 system = System(cpu = cpu, physmem = SimpleMemory(),
                 membus = NoncoherentBus(width = 16))
+system.clock = '1GHz'
 
 # add a communication monitor, and also trace all the packets
 system.monitor = CommMonitor(trace_file = "monitor.ptrc.gz")
diff -r fc7d56547e33 -r 54a18bf193b4 tests/configs/twosys-tsunami-simple-atomic.py
--- a/tests/configs/twosys-tsunami-simple-atomic.py	Fri May 24 11:25:10 2013 +0100
+++ b/tests/configs/twosys-tsunami-simple-atomic.py	Fri May 24 11:35:05 2013 +0100
@@ -34,6 +34,7 @@
 
 test_sys = makeLinuxAlphaSystem('atomic', SimpleMemory,
                                  SysConfig('netperf-stream-client.rcS'))
+test_sys.clock = '1GHz'
 test_sys.cpu = AtomicSimpleCPU(cpu_id=0)
 # create the interrupt controller
 test_sys.cpu.createInterruptController()
@@ -48,6 +49,7 @@
 
 drive_sys = makeLinuxAlphaSystem('atomic', SimpleMemory,
                                  SysConfig('netperf-server.rcS'))
+drive_sys.clock = '1GHz'
 drive_sys.cpu = AtomicSimpleCPU(cpu_id=0)
 # create the interrupt controller
 drive_sys.cpu.createInterruptController()