diff --git a/configs/example/ruby_direct_test.py b/configs/example/ruby_direct_test.py
index 60defb9f59..163b38fede 100644
--- a/configs/example/ruby_direct_test.py
+++ b/configs/example/ruby_direct_test.py
@@ -97,7 +97,13 @@ system.clk_domain = SrcClockDomain(clock = options.sys_clock,
 system.cpu = RubyDirectedTester(requests_to_complete = options.requests,
                                 generator = generator)
 
-Ruby.create_system(options, False, system)
+# the ruby tester reuses num_cpus to specify the
+# number of cpu ports connected to the tester object, which
+# is stored in system.cpu. because there is only ever one
+# tester object, num_cpus is not necessarily equal to the
+# size of system.cpu
+cpu_list = [ system.cpu ] * options.num_cpus
+Ruby.create_system(options, False, system, cpus=cpu_list)
 
 # Since Ruby runs at an independent frequency, create a seperate clock
 system.ruby.clk_domain = SrcClockDomain(clock = options.ruby_clock,
diff --git a/configs/example/ruby_gpu_random_test.py b/configs/example/ruby_gpu_random_test.py
index 133c13a4bb..745ad0298b 100644
--- a/configs/example/ruby_gpu_random_test.py
+++ b/configs/example/ruby_gpu_random_test.py
@@ -249,8 +249,15 @@ system.dma_devices = dma_devices
 #
 # Create the Ruby system
 #
+# the ruby tester reuses num_cpus to specify the
+# number of cpu ports connected to the tester object, which
+# is stored in system.cpu. because there is only ever one
+# tester object, num_cpus is not necessarily equal to the
+# size of system.cpu
+cpu_list = [ system.cpu ] * options.num_cpus
 Ruby.create_system(options = options, full_system = False,
-                   system = system, dma_ports = system.dma_devices)
+                   system = system, dma_ports = system.dma_devices,
+                   cpus = cpu_list)
 
 #
 # The tester is most effective when randomization is turned on and
diff --git a/configs/example/ruby_random_test.py b/configs/example/ruby_random_test.py
index dc768270a1..da824295dc 100644
--- a/configs/example/ruby_random_test.py
+++ b/configs/example/ruby_random_test.py
@@ -103,7 +103,13 @@ system.voltage_domain = VoltageDomain(voltage = options.sys_voltage)
 system.clk_domain = SrcClockDomain(clock = options.sys_clock,
                                    voltage_domain = system.voltage_domain)
 
-Ruby.create_system(options, False, system)
+# the ruby tester reuses num_cpus to specify the
+# number of cpu ports connected to the tester object, which
+# is stored in system.cpu. because there is only ever one
+# tester object, num_cpus is not necessarily equal to the
+# size of system.cpu
+cpu_list = [ system.cpu ] * options.num_cpus
+Ruby.create_system(options, False, system, cpus=cpu_list)
 
 # Create a seperate clock domain for Ruby
 system.ruby.clk_domain = SrcClockDomain(clock = options.ruby_clock,
diff --git a/configs/ruby/CHI.py b/configs/ruby/CHI.py
index 0a49371d84..db686eddad 100644
--- a/configs/ruby/CHI.py
+++ b/configs/ruby/CHI.py
@@ -646,7 +646,7 @@ def noc_params_from_config(config, noc_params):
 
 
 def create_system(options, full_system, system, dma_ports, bootmem,
-                  ruby_system):
+                  ruby_system, cpus):
 
     if buildEnv['PROTOCOL'] != 'CHI':
         m5.panic("This script requires the CHI build")
@@ -721,10 +721,10 @@ def create_system(options, full_system, system, dma_ports, bootmem,
     all_cntrls = []
 
     # Creates on RNF per cpu with priv l2 caches
-    assert(len(system.cpu) == options.num_cpus)
+    assert(len(cpus) == options.num_cpus)
     ruby_system.rnf = [ CHI_RNF([cpu], ruby_system, L1ICache, L1DCache,
                                 system.cache_line_size.value)
-                        for cpu in system.cpu ]
+                        for cpu in cpus ]
     for rnf in ruby_system.rnf:
         rnf.addPrivL2Cache(L2Cache)
         cpu_sequencers.extend(rnf.getSequencers())
diff --git a/configs/ruby/MESI_Three_Level.py b/configs/ruby/MESI_Three_Level.py
index 91ccb58963..bd0e97ea73 100644
--- a/configs/ruby/MESI_Three_Level.py
+++ b/configs/ruby/MESI_Three_Level.py
@@ -58,7 +58,7 @@ def define_options(parser):
     return
 
 def create_system(options, full_system, system, dma_ports, bootmem,
-                  ruby_system):
+                  ruby_system, cpus):
 
     if buildEnv['PROTOCOL'] != 'MESI_Three_Level':
         fatal("This script requires the MESI_Three_Level protocol to be\
@@ -108,17 +108,7 @@ def create_system(options, full_system, system, dma_ports, bootmem,
                 start_index_bit = block_size_bits,
                 replacement_policy = LRURP())
 
-            # the ruby random tester reuses num_cpus to specify the
-            # number of cpu ports connected to the tester object, which
-            # is stored in system.cpu. because there is only ever one
-            # tester object, num_cpus is not necessarily equal to the
-            # size of system.cpu; therefore if len(system.cpu) == 1
-            # we use system.cpu[0] to set the clk_domain, thereby ensuring
-            # we don't index off the end of the cpu list.
-            if len(system.cpu) == 1:
-                clk_domain = system.cpu[0].clk_domain
-            else:
-                clk_domain = system.cpu[i].clk_domain
+            clk_domain = cpus[i].clk_domain
 
             # Ruby prefetcher
             prefetcher = RubyPrefetcher(
diff --git a/configs/ruby/MESI_Three_Level_HTM.py b/configs/ruby/MESI_Three_Level_HTM.py
index f39e457af3..946b6412b1 100644
--- a/configs/ruby/MESI_Three_Level_HTM.py
+++ b/configs/ruby/MESI_Three_Level_HTM.py
@@ -58,7 +58,7 @@ def define_options(parser):
     return
 
 def create_system(options, full_system, system, dma_ports, bootmem,
-                  ruby_system):
+                  ruby_system, cpus):
 
     if buildEnv['PROTOCOL'] != 'MESI_Three_Level_HTM':
         fatal("This script requires the MESI_Three_Level protocol to be\
@@ -108,17 +108,7 @@ def create_system(options, full_system, system, dma_ports, bootmem,
                 start_index_bit = block_size_bits,
                 replacement_policy = LRURP())
 
-            # the ruby random tester reuses num_cpus to specify the
-            # number of cpu ports connected to the tester object, which
-            # is stored in system.cpu. because there is only ever one
-            # tester object, num_cpus is not necessarily equal to the
-            # size of system.cpu; therefore if len(system.cpu) == 1
-            # we use system.cpu[0] to set the clk_domain, thereby ensuring
-            # we don't index off the end of the cpu list.
-            if len(system.cpu) == 1:
-                clk_domain = system.cpu[0].clk_domain
-            else:
-                clk_domain = system.cpu[i].clk_domain
+            clk_domain = cpus[i].clk_domain
 
             # Ruby prefetcher
             prefetcher = RubyPrefetcher(
diff --git a/configs/ruby/MESI_Two_Level.py b/configs/ruby/MESI_Two_Level.py
index 96650e0106..e6d91cea33 100644
--- a/configs/ruby/MESI_Two_Level.py
+++ b/configs/ruby/MESI_Two_Level.py
@@ -42,7 +42,7 @@ def define_options(parser):
     return
 
 def create_system(options, full_system, system, dma_ports, bootmem,
-                  ruby_system):
+                  ruby_system, cpus):
 
     if buildEnv['PROTOCOL'] != 'MESI_Two_Level':
         fatal("This script requires the MESI_Two_Level protocol to be built.")
@@ -80,17 +80,7 @@ def create_system(options, full_system, system, dma_ports, bootmem,
 
         prefetcher = RubyPrefetcher()
 
-        # the ruby random tester reuses num_cpus to specify the
-        # number of cpu ports connected to the tester object, which
-        # is stored in system.cpu. because there is only ever one
-        # tester object, num_cpus is not necessarily equal to the
-        # size of system.cpu; therefore if len(system.cpu) == 1
-        # we use system.cpu[0] to set the clk_domain, thereby ensuring
-        # we don't index off the end of the cpu list.
-        if len(system.cpu) == 1:
-            clk_domain = system.cpu[0].clk_domain
-        else:
-            clk_domain = system.cpu[i].clk_domain
+        clk_domain = cpus[i].clk_domain
 
         l1_cntrl = L1Cache_Controller(version = i, L1Icache = l1i_cache,
                                       L1Dcache = l1d_cache,
diff --git a/configs/ruby/MI_example.py b/configs/ruby/MI_example.py
index 6e5c8b4e27..79259d9339 100644
--- a/configs/ruby/MI_example.py
+++ b/configs/ruby/MI_example.py
@@ -41,7 +41,7 @@ def define_options(parser):
     return
 
 def create_system(options, full_system, system, dma_ports, bootmem,
-                  ruby_system):
+                  ruby_system, cpus):
 
     if buildEnv['PROTOCOL'] != 'MI_example':
         panic("This script requires the MI_example protocol to be built.")
@@ -73,17 +73,7 @@ def create_system(options, full_system, system, dma_ports, bootmem,
                         start_index_bit = block_size_bits)
 
 
-        # the ruby random tester reuses num_cpus to specify the
-        # number of cpu ports connected to the tester object, which
-        # is stored in system.cpu. because there is only ever one
-        # tester object, num_cpus is not necessarily equal to the
-        # size of system.cpu; therefore if len(system.cpu) == 1
-        # we use system.cpu[0] to set the clk_domain, thereby ensuring
-        # we don't index off the end of the cpu list.
-        if len(system.cpu) == 1:
-            clk_domain = system.cpu[0].clk_domain
-        else:
-            clk_domain = system.cpu[i].clk_domain
+        clk_domain = cpus[i].clk_domain
 
         # Only one unified L1 cache exists. Can cache instructions and data.
         l1_cntrl = L1Cache_Controller(version=i, cacheMemory=cache,
diff --git a/configs/ruby/MOESI_CMP_directory.py b/configs/ruby/MOESI_CMP_directory.py
index 5366fe7ab1..1257f6de67 100644
--- a/configs/ruby/MOESI_CMP_directory.py
+++ b/configs/ruby/MOESI_CMP_directory.py
@@ -59,7 +59,7 @@ def define_options(parser):
     return
 
 def create_system(options, full_system, system, dma_ports, bootmem,
-                  ruby_system):
+                  ruby_system, cpus):
 
     if buildEnv['PROTOCOL'] != 'MOESI_CMP_directory':
         panic("This script requires the MOESI_CMP_directory protocol to be built.")
@@ -94,17 +94,7 @@ def create_system(options, full_system, system, dma_ports, bootmem,
                             start_index_bit = block_size_bits,
                             is_icache = False)
 
-        # the ruby random tester reuses num_cpus to specify the
-        # number of cpu ports connected to the tester object, which
-        # is stored in system.cpu. because there is only ever one
-        # tester object, num_cpus is not necessarily equal to the
-        # size of system.cpu; therefore if len(system.cpu) == 1
-        # we use system.cpu[0] to set the clk_domain, thereby ensuring
-        # we don't index off the end of the cpu list.
-        if len(system.cpu) == 1:
-            clk_domain = system.cpu[0].clk_domain
-        else:
-            clk_domain = system.cpu[i].clk_domain
+        clk_domain = cpus[i].clk_domain
 
         l1_cntrl = L1Cache_Controller(version=i, L1Icache=l1i_cache,
                                       L1Dcache=l1d_cache,
diff --git a/configs/ruby/MOESI_CMP_token.py b/configs/ruby/MOESI_CMP_token.py
index 28ec52f3dd..91d02a0147 100644
--- a/configs/ruby/MOESI_CMP_token.py
+++ b/configs/ruby/MOESI_CMP_token.py
@@ -49,7 +49,7 @@ def define_options(parser):
           help="allow migratory sharing for atomic only accessed blocks")
 
 def create_system(options, full_system, system, dma_ports, bootmem,
-                  ruby_system):
+                  ruby_system, cpus):
 
     if buildEnv['PROTOCOL'] != 'MOESI_CMP_token':
         panic("This script requires the MOESI_CMP_token protocol to be built.")
@@ -89,17 +89,7 @@ def create_system(options, full_system, system, dma_ports, bootmem,
                             assoc = options.l1d_assoc,
                             start_index_bit = block_size_bits)
 
-        # the ruby random tester reuses num_cpus to specify the
-        # number of cpu ports connected to the tester object, which
-        # is stored in system.cpu. because there is only ever one
-        # tester object, num_cpus is not necessarily equal to the
-        # size of system.cpu; therefore if len(system.cpu) == 1
-        # we use system.cpu[0] to set the clk_domain, thereby ensuring
-        # we don't index off the end of the cpu list.
-        if len(system.cpu) == 1:
-            clk_domain = system.cpu[0].clk_domain
-        else:
-            clk_domain = system.cpu[i].clk_domain
+        clk_domain = cpus[i].clk_domain
 
         l1_cntrl = L1Cache_Controller(version=i, L1Icache=l1i_cache,
                                       L1Dcache=l1d_cache,
diff --git a/configs/ruby/MOESI_hammer.py b/configs/ruby/MOESI_hammer.py
index 1e00f0f479..adff1c9a38 100644
--- a/configs/ruby/MOESI_hammer.py
+++ b/configs/ruby/MOESI_hammer.py
@@ -52,7 +52,7 @@ def define_options(parser):
           help="Hammer: enable Full-bit Directory")
 
 def create_system(options, full_system, system, dma_ports, bootmem,
-                  ruby_system):
+                  ruby_system, cpus):
 
     if buildEnv['PROTOCOL'] != 'MOESI_hammer':
         panic("This script requires the MOESI_hammer protocol to be built.")
@@ -88,17 +88,7 @@ def create_system(options, full_system, system, dma_ports, bootmem,
                            assoc = options.l2_assoc,
                            start_index_bit = block_size_bits)
 
-        # the ruby random tester reuses num_cpus to specify the
-        # number of cpu ports connected to the tester object, which
-        # is stored in system.cpu. because there is only ever one
-        # tester object, num_cpus is not necessarily equal to the
-        # size of system.cpu; therefore if len(system.cpu) == 1
-        # we use system.cpu[0] to set the clk_domain, thereby ensuring
-        # we don't index off the end of the cpu list.
-        if len(system.cpu) == 1:
-            clk_domain = system.cpu[0].clk_domain
-        else:
-            clk_domain = system.cpu[i].clk_domain
+        clk_domain = cpus[i].clk_domain
 
         l1_cntrl = L1Cache_Controller(version=i, L1Icache=l1i_cache,
                                       L1Dcache=l1d_cache, L2cache=l2_cache,
diff --git a/configs/ruby/Ruby.py b/configs/ruby/Ruby.py
index 2bed3419cf..e7609f42d4 100644
--- a/configs/ruby/Ruby.py
+++ b/configs/ruby/Ruby.py
@@ -172,7 +172,7 @@ def create_topology(controllers, options):
     return topology
 
 def create_system(options, full_system, system, piobus = None, dma_ports = [],
-                  bootmem=None):
+                  bootmem=None, cpus=None):
 
     system.ruby = RubySystem()
     ruby = system.ruby
@@ -185,12 +185,15 @@ def create_system(options, full_system, system, piobus = None, dma_ports = [],
         Network.create_network(options, ruby)
     ruby.network = network
 
+    if cpus is None:
+        cpus = system.cpu
+
     protocol = buildEnv['PROTOCOL']
     exec("from . import %s" % protocol)
     try:
         (cpu_sequencers, dir_cntrls, topology) = \
              eval("%s.create_system(options, full_system, system, dma_ports,\
-                                    bootmem, ruby)"
+                                    bootmem, ruby, cpus)"
                   % protocol)
     except:
         print("Error: could not create sytem for ruby protocol %s" % protocol)
diff --git a/tests/configs/gpu-randomtest-ruby.py b/tests/configs/gpu-randomtest-ruby.py
index 3d088f4ecc..246affa7eb 100644
--- a/tests/configs/gpu-randomtest-ruby.py
+++ b/tests/configs/gpu-randomtest-ruby.py
@@ -100,7 +100,13 @@ system.clk_domain = SrcClockDomain(clock = '1GHz',
 
 system.mem_ranges = AddrRange('256MB')
 
-Ruby.create_system(options, False, system)
+# the ruby tester reuses num_cpus to specify the
+# number of cpu ports connected to the tester object, which
+# is stored in system.cpu. because there is only ever one
+# tester object, num_cpus is not necessarily equal to the
+# size of system.cpu
+cpu_list = [ system.cpu ] * options.num_cpus
+Ruby.create_system(options, False, system, cpus=cpu_list)
 
 # Create a separate clock domain for Ruby
 system.ruby.clk_domain = SrcClockDomain(clock = '1GHz',
diff --git a/tests/configs/rubytest-ruby.py b/tests/configs/rubytest-ruby.py
index 5c01cffee9..0db7e38060 100644
--- a/tests/configs/rubytest-ruby.py
+++ b/tests/configs/rubytest-ruby.py
@@ -80,7 +80,13 @@ system.clk_domain = SrcClockDomain(clock = '1GHz',
 
 system.mem_ranges = AddrRange('256MB')
 
-Ruby.create_system(options, False, system)
+# the ruby tester reuses num_cpus to specify the
+# number of cpu ports connected to the tester object, which
+# is stored in system.cpu. because there is only ever one
+# tester object, num_cpus is not necessarily equal to the
+# size of system.cpu
+cpu_list = [ system.cpu ] * options.num_cpus
+Ruby.create_system(options, False, system, cpus=cpu_list)
 
 # Create a separate clock domain for Ruby
 system.ruby.clk_domain = SrcClockDomain(clock = '1GHz',