mem: Add DRAM device size and check against config

This patch adds the size of the DRAM device to the DRAM config. It
also compares the actual DRAM size (calculated using information from
the config) to the size defined in the system. If these two values do
not match gem5 will print a warning. In order to do correct DRAM
research the size of the memory defined in the system should match the
size of the DRAM in the config. The timing and current parameters
found in the DRAM configs are defined for a DRAM device with a
specific size and would differ for another device with a different
size.

src/mem/DRAMCtrl.py

@@ -96,6 +96,9 @@ class DRAMCtrl(AbstractMemory):
     max_accesses_per_row = Param.Unsigned(16, "Max accesses per row before "
                                           "closing");
 
+    # size of DRAM Chip in Bytes
+    device_size = Param.MemorySize("Size of DRAM chip")
+
     # pipeline latency of the controller and PHY, split into a
     # frontend part and a backend part, with reads and writes serviced
     # by the queues only seeing the frontend contribution, and reads
@@ -305,6 +308,9 @@ class DRAMCtrl(AbstractMemory):
 # timings based on a DDR3-1600 4 Gbit datasheet (Micron MT41J512M8) in
 # an 8x8 configuration.
 class DDR3_1600_x64(DRAMCtrl):
+    # size of device in bytes
+    device_size = '512MB'
+
     # 8x8 configuration, 8 devices each with an 8-bit interface
     device_bus_width = 8
 
@@ -397,6 +403,9 @@ class DDR3_2133_x64(DDR3_1600_x64):
 # timings based on a DDR4-2400 4 Gbit datasheet (Micron MT40A512M8)
 # in an 8x8 configuration.
 class DDR4_2400_x64(DRAMCtrl):
+    # size of device
+    device_size = '512MB'
+
     # 8x8 configuration, 8 devices each with an 8-bit interface
     device_bus_width = 8
 
@@ -488,6 +497,9 @@ class LPDDR2_S4_1066_x32(DRAMCtrl):
     # No DLL in LPDDR2
     dll = False
 
+    # size of device
+    device_size = '512MB'
+
     # 1x32 configuration, 1 device with a 32-bit interface
     device_bus_width = 32
 
@@ -572,6 +584,9 @@ class WideIO_200_x128(DRAMCtrl):
     # No DLL for WideIO
     dll = False
 
+    # size of device
+    device_size = '1024MB'
+
     # 1x128 configuration, 1 device with a 128-bit interface
     device_bus_width = 128
 
@@ -638,6 +653,9 @@ class LPDDR3_1600_x32(DRAMCtrl):
     # No DLL for LPDDR3
     dll = False
 
+    # size of device
+    device_size = '512MB'
+
     # 1x32 configuration, 1 device with a 32-bit interface
     device_bus_width = 32
 

src/mem/dram_ctrl.cc

@@ -62,6 +62,7 @@ DRAMCtrl::DRAMCtrl(const DRAMCtrlParams* p) :
     nextReqEvent(this), respondEvent(this), activateEvent(this),
     prechargeEvent(this), refreshEvent(this), powerEvent(this),
     drainManager(NULL),
+    deviceSize(p->device_size),
     deviceBusWidth(p->device_bus_width), burstLength(p->burst_length),
     deviceRowBufferSize(p->device_rowbuffer_size),
     devicesPerRank(p->devices_per_rank),
@@ -139,6 +140,16 @@ DRAMCtrl::DRAMCtrl(const DRAMCtrlParams* p) :
     // determine the rows per bank by looking at the total capacity
     uint64_t capacity = ULL(1) << ceilLog2(AbstractMemory::size());
 
+    // determine the dram actual capacity from the DRAM config in Mbytes
+    uint64_t deviceCapacity = deviceSize / (1024 * 1024) * devicesPerRank *
+        ranksPerChannel;
+
+    // if actual DRAM size does not match memory capacity in system warn!
+    if (deviceCapacity != capacity / (1024 * 1024))
+        warn("DRAM device capacity (%d Mbytes) does not match the "
+             "address range assigned (%d Mbytes)\n", deviceCapacity,
+             capacity / (1024 * 1024));
+
     DPRINTF(DRAM, "Memory capacity %lld (%lld) bytes\n", capacity,
             AbstractMemory::size());
 

src/mem/dram_ctrl.hh

@@ -463,6 +463,7 @@ class DRAMCtrl : public AbstractMemory
      * The rowsPerBank is determined based on the capacity, number of
      * ranks and banks, the burst size, and the row buffer size.
      */
+    const uint32_t deviceSize;
     const uint32_t deviceBusWidth;
     const uint32_t burstLength;
     const uint32_t deviceRowBufferSize;