Fix Physical Memory to allow memory sizes bigger than 128MB.

Kinda port DRAM to new memory system. The code is *really* ugly (not my fault) and right now something about the stats it uses
causes a simulator segfault.

src/SConscript:
    Add dram.cc to sconscript
src/mem/physical.cc:
src/mem/physical.hh:
    Add params struct to physical memory, use params, make latency function be virtual
src/python/m5/objects/PhysicalMemory.py:
    Add DRAMMemory python class

--HG--
extra : convert_revision : 5bd9f2e071c62da89e8efa46fa016f342c01535d

src/python/m5/objects/PhysicalMemory.py

@@ -7,3 +7,21 @@ class PhysicalMemory(MemObject):
     range = Param.AddrRange("Device Address")
     file = Param.String('', "memory mapped file")
     latency = Param.Latency(Parent.clock, "latency of an access")
+
+class DRAMMemory(PhysicalMemory):
+    type = 'DRAMMemory'
+    # Many of these should be observed from the configuration
+    cpu_ratio = Param.Int(5,"ratio between CPU speed and memory bus speed")
+    mem_type = Param.String("SDRAM", "Type of DRAM (DRDRAM, SDRAM)")
+    mem_actpolicy = Param.String("open", "Open/Close policy")
+    memctrladdr_type = Param.String("interleaved", "Mapping interleaved or direct")
+    bus_width = Param.Int(16, "")
+    act_lat = Param.Int(2, "RAS to CAS delay")
+    cas_lat = Param.Int(1, "CAS delay")
+    war_lat = Param.Int(2, "write after read delay")
+    pre_lat = Param.Int(2, "precharge delay")
+    dpl_lat = Param.Int(2, "data in to precharge delay")
+    trc_lat = Param.Int(6, "row cycle delay")
+    num_banks = Param.Int(4, "Number of Banks")
+    num_cpus = Param.Int(4, "Number of CPUs connected to DRAM")
+