This directory contains C# code that is loaded into renode. It implements the interface ReNode uses to interact with CPU type bus objects. This code translates ReNode calls to the “C” callable interface that is implemented by the mpact_sim/util/renode C++ library code, and which is linked with an mpact simulator instance. This library code translates and forwards the required calls to the RenodeDebugInterface that is implemented separately for each mpact simulator target. For details see the specific targets of interest.
The C# code in MpactBaseCPU.cs implements two classes: MpactBaseCPU and MpactPeripheral. The first derives from ReNode's BaseCPU class, and provides a CPU interface to ReNode that dynamically loads and controls an mpact simulator in a dynamic library using a small “C” linkage interface. The second implements a bus target interface so that any memory the simulator manages can be made accessible to the ReNode system model from the system bus.
The MpactBaseCPU.cs should be placed in the renode subdirectory src/Plugins/MpactPlugin.
The CPU can be instantiated as follows:
mytype: MpactCPU.MpactBaseCPU @ sysbus
id: 1
cpuType: "Mpact.MyType"
endianness: Endianess.LittleEndian
memoryBase: 0x80000000
memorySize: 0x10000000
This instantiates an object of MpactCPU.MpactBaseCPU, connected to sysbus with the instance name mytype. The object is constructed using the parameters listed below.
The peripheral can be instantiated as follows:
mytype_mem : MpactCPU.MpactPeripheral @ sysbus 0x80000000
size: 0x10000000
baseAddress: 0x80000000
mpactCpu: mytype
In this case, a bus target is defined at address 0x8000‘0000 on sysbus, with a size of 0x1000’0000, and connects with the mytype CPU instance. When ReNode makes references to this peripheral, only the offset from the mapped address is passed on. The value of the constructor parameter baseAddress is added to every such reference. It does not have to be the same as the address to which the peripheral is added to the bus, thus allowing the requests to be remapped in memory.
The library code defines and implements code for the “C” linkage interface that is called by MpactBaseCPU, and the code necessary to manage one or multiple instances of mpact simulators. This code is linked in with the simulator and a simulator target specific implementation of the RenodeDebugInterface.
The name of the dynamic library is passed to ReNode by setting the instance property CpuLibraryPath in either the ReNode platform definition (.repl) or script (.resc) file.
The MpactRiscVCPU class in MpactRiscVCPU.cs inherits from MpactBaseCPU. It adds 4 configuration items to the base class:
InstProfile is a boolean that when true enables instruction profiling in the simulator. Following execution there will be a .csv file that contains a table of instruction addresses and the number of times each instruction was executed.MemProfiler is a boolean that when true enables data profiling in the simulator. Following execution there will be a .csv file that contains a table of first and last word addresses in a range, and the size of the range. It does not contain an access count.StackEnd is a ulong that contains the address of the end of the stack. Some RiscV libraries don't properly initialize the stack pointer (i.e., it is left at 0x0). Setting the stack end and stack size will cause the simulator to initialize the stack pointer to the value of the sum of stack end and stack size.StackSize is a ulong that contains the size to use for the stack.The MpactRiscVCPU class can be used with either the librenode_mpact_riscv32.so or the librenode_mpact_riscv64.so targets in the mpact_riscv repository.
The MpactCheriotCPU class in MpactCheriotCPU.cs inherits from MpactBaseCPU. It adds 4 configuration items to the base class:
InstProfile is a boolean that when true enables instruction profiling in the simulator. Following execution there will be a .csv file that contains a table of instruction addresses and the number of times each instruction was executed.MemProfiler is a boolean that when true enabled data profiling in the simulator. Following execution there will be a .csv file that contains a table of first and last word addresses in a range, and the size of the range. It does not contain an access count.The MpactCheriotCPU class can be used with the librenode_mpact_cheriot.so target in the mpact_cheriot repository.