Mem: Make SimpleMemory single ported

This patch changes the simple memory to have a single slave port
rather than a vector port. The simple memory makes no attempts at
modelling the contention between multiple ports, and any such
multiplexing and demultiplexing could be done in a bus (or crossbar)
outside the memory controller. This scenario also matches with the
ongoing work on a SimpleDRAM model, which will be a single-ported
single-channel controller that can be used in conjunction with a bus
(or crossbar) to create a multi-port multi-channel controller.

There are only very few regressions that make use of the vector port,
and these are all for functional accesses only. To facilitate these
cases, memtest and memtest-ruby have been updated to also have a
"functional" bus to perform the (de)multiplexing of the functional
memory accesses.

2 files changed, 10 insertions, 2 deletions

diff --git a/tests/configs/memtest-ruby.py b/tests/configs/memtest-ruby.py
index 008daa1ad..560a8fd65 100644
--- a/tests/configs/memtest-ruby.py
+++ b/tests/configs/memtest-ruby.py
@@ -79,6 +79,7 @@ options.num_cpus = nb_cores
 # system simulated
 system = System(cpu = cpus,
                 funcmem = SimpleMemory(in_addr_map = False),
+                funcbus = NoncoherentBus(),
                 physmem = SimpleMemory())
 
 Ruby.create_system(options, system)
@@ -91,7 +92,7 @@ for (i, ruby_port) in enumerate(system.ruby._cpu_ruby_ports):
      # physmem, respectively
      #
      cpus[i].test = ruby_port.slave
-     cpus[i].functional = system.funcmem.port
+     cpus[i].functional = system.funcbus.slave
      
      #
      # Since the memtester is incredibly bursty, increase the deadlock
@@ -105,6 +106,9 @@ for (i, ruby_port) in enumerate(system.ruby._cpu_ruby_ports):
      #
      ruby_port.access_phys_mem = False
 
+# connect reference memory to funcbus
+system.funcmem.port = system.funcbus.master
+
 # -----------------------
 # run simulation
 # -----------------------
diff --git a/tests/configs/memtest.py b/tests/configs/memtest.py
index 0add2158f..57f45b1d4 100644
--- a/tests/configs/memtest.py
+++ b/tests/configs/memtest.py
@@ -57,6 +57,7 @@ cpus = [ MemTest() for i in xrange(nb_cores) ]
 
 # system simulated
 system = System(cpu = cpus, funcmem = SimpleMemory(in_addr_map = False),
+                funcbus = NoncoherentBus(),
                 physmem = SimpleMemory(),
                 membus = CoherentBus(clock="500GHz", width=16))
 
@@ -73,10 +74,13 @@ for cpu in cpus:
     cpu.l1c = L1(size = '32kB', assoc = 4)
     cpu.l1c.cpu_side = cpu.test
     cpu.l1c.mem_side = system.toL2Bus.slave
-    system.funcmem.port = cpu.functional
+    system.funcbus.slave = cpu.functional
 
 system.system_port = system.membus.slave
 
+# connect reference memory to funcbus
+system.funcmem.port = system.funcbus.master
+
 # connect memory to membus
 system.physmem.port = system.membus.master