Another RISC-V ISA simulator.

This code is suitable to hard refactor at any time

This is another RISC-V ISA simulator, this is coded in SystemC + TLM-2. It supports RV32IMAC Instruction set by now.

Table of Contents

• Another RISC-V ISA simulator.
• Table of Contents
  • Description
    • Structure
    • Memory Map
  • TODO
  • Compile
  • Cross-compiler
  • Debug
  • Docker container
    • How to use Docker
  • Test
    • C code
    • FreeRTOS
  • Documentation
    • Publications
  • Contribute
  • Authors and credits
  • License

Description

Brief description of the modules:

• CPU: Top entity that includes all other modules.
• Memory: Memory highly based on TLM-2 example with read file capability
• Registers: Implements the register file, PC register & CSR registers
• Instruction: Decodes instruction type and keeps instruction field
• BASE_ISA: Executes Base ISA, Zifencei and Zicsr.
  • C_extension: Decodes & Executes Compressed instructions (C extension)
  • M_extension: Decodes & Executes Multiplication and Division instructions (M extension)
  • A_extension: Decodes & Executes Atomic instructions (A extension)
• Simulator: Top-level entity that builds & starts the simulation
• BusCtrl: Simple bus manager
• Trace: Simple trace peripheral
• Timer: Simple IRQ programable real-time counter peripheral
• Debug: GDB server for remote debugging (Beta)

Helper classes:

• Performance: Performance indicators stores here (singleton class)
• Log: Log class to log them all (singleton class)

Current performance is about 3.000.000 instructions / sec in a Intel Core i5-5200@2.2Ghz and about 4.500.000 instructions / sec in a Intel Core i7-8550U@1.8Ghz.

Trace perihperal creates a xterm window where it prints out all received data.

Structure

Memory map

TODO

This is a preliminar and incomplete version.

Task to do:

• Implement all missing instructions (Execute)
• Implement CSRs (where/how?)
• Add full support to read file with memory contents (to memory.h)
  • .elf files
  • .hex files (only partial .hex support)
• Connect some TLM peripherals
  • Debug module similiar to ARM's ITM
  • Some standard UART model
  • ...
• Implement interrupts
  • implement timer (mtimecmp) & timer interrupt
  • generic IRQ comtroller
• Test, test, test & test. I'm sure there are a lot of some bugs in the code
  • riscv-test almost complete (see Test)
  • riscv-compliance

• Improve structure and modules hierarchy
• Add 64 & 128 bits architecture (RV64I, RV128I)
• Debug capabilities

Compile

In order to compile the project you need SystemC-2.3.2 installed in your system. Just change SYSTEMC path in Makefile.

$ make

Then, you need to modifiy your LD_LIBRARY_PATH environtment variable to add path systemc library. In my case:

$ export LD_LIBRARY_PATH=/home/marius/Work/RiscV/code/systemc-2.3.2/lib-linux64

And then you can execute the simulator:

$ ./RISCV_TLM asm/BasicLoop.hex

Using cmake

It is possible to use cmake:

mkdir build
cd build
cmake ..
make

note that SystemC must be compiled with cmake:

cd <systemc directory>
mkdir build
cd build
cmake ../ -DCMAKE_CXX_STANDARD=17
make

Arguments

-L loglevel: 3 for detailed (INFO) log, 0 to ERROR log level

-f filename .hex filename to use

-D Enter in Debug mode, simulator starts gdb server (Beta)

Cross-compiler

It is possible to use gcc as risc-v compiler. Follow the instructions (from https://github.com/riscv/riscv-gnu-toolchain):

$ git clone --recursive https://github.com/riscv/riscv-gnu-toolchain
$ cd riscv-gnu-toolchain
$ ./configure --prefix=/opt/riscv --with-arch=rv32gc --with-abi=ilp32
$ make
...
wait for long time ...
...
$ export PATH=$PATH:/opt/riscv/bin

In test/C/long_test/ example there is a Makefile that compiles a project with any .c files and links them against new-lib nano. There is a Helper_functions.c file with defiitions of all missing functions needed by the library (_read(), _close(), _fstat_r(), _lseek_r(), _isatty_r(), _write()). All of them are defined empty except _write() that is written to use the Trace perihperal. The definition of the function _write() allows developer to use printf() as usual and the stdout will be redirected to the Trace perihperal.

Debug

It is possible to debug an application running in RISC-V-TLM simulator. It is tested with riscv32-unknown-elf-gdb version 8.3.0.20190516-git and eclipse. Configure a "C/C++ Remote Application" debug configuration as the figure

gdbinit.txt file must contain:

set debug remote 1
set arch riscv:rv32

With this configuration, eclipse debuggins is almost normal (I experienced some problems wiith "step-over" and "step-into" commands)

Docker container

There is a Docker container available with the latest release at https://hub.docker.com/r/mariusmm/riscv-tlm. This container has RISCV-TLM already build at /usr/src/riscv64/RISCV-TLM directory.

How to use Docker

$ docker pull mariusmm/riscv-tlm
$ docker run -v <path_to_RISCV-V-TLM>/:/tmp -u $UID -e DISPLAY=$DISPLAY --volume="/tmp/.X11-unix:/tmp/.X11-unix:rw"  -it mariusmm/riscv-tlm /bin/bash

$ ./RISC-V-TLM/build/RISCV_TLM /tmp/<your_hex_file>

or you can call binary inside docker image directly:

$ docker run -v <path_to_RISCV-V-TLM>/:/tmp -u $UID -e DISPLAY=$DISPLAY --volume="/tmp/.X11-unix:/tmp/.X11-unix:rw"  -it mariusmm/riscv-tlm /usr/src/riscv64/RISC-V-TLM/RISCV_TLM /tmp/<your_hex_file>

I'm using docker image zmors/riscv_gcc to have a cross-compiler, I'm using both docker images this way:

console1:
$ docker run -v /tmp:/PRJ -it zmors/riscv_gcc:1  bash

# cd /PRJ/func3
# make

console2:
$ docker run -v /tmp:/tmp -u $UID -e DISPLAY=$DISPLAY --volume="/tmp/.X11-unix:/tmp/.X11-unix:rw" -it mariusmm/riscv-tlm /bin/bash

# cd /usr/src/riscv64/RISC-V-TLM/ 
# ./RISCV-TLM /tmp/file.hex
...

or

...
console 2:
$  docker run -v /tmp/tmp -it  mariusmm/riscv-tlm /usr/src/riscv64/RISC-V-TLM/RISCV_TLM /tmp/file.hex

Performance is not affected by running the simulator inside the container

Test

See Test page for more information.

In the asm directory there are some basic assembly examples.

I "compile" one file with the follwing command:

$ cd asm
$ riscv32-unknown-elf-as  EternalLoop.asm -o EternalLoop.o
$ riscv32-unknown-elf-ld EternalLoop.o -o EternalLoop.elf
$ riscv32-unknown-elf-objcopy -O ihex EternalLoop.elf EternalLoop.hex
$ cd ..
$ ./RISCV_SCTLM asm/EternalLoop.hex

This example needs that you hit Ctr+C to stop execution.

C code

The C directory contains simple examples in C. Each directory contains an example, to compile it just:

$ make

and then execute the .hex file like the example before.

FreeRTOS

FreeRTOS can run in this simulator!

In test/FreeRTOS/ directory there is portable files (port.c, portmacro.c portasm.S) and main file (freertos_test.c) ported to this RISC-V model.

Documentation

The code is documented using doxygen. In the doc folder there is a Doxygen.cfg file ready to be used.

Contribute

There are several ways to contribute to this project:

• Test
• Pull request are welcome (see TODO list)
• Good documentation
• RTL-Level simulation

Authors and credits

RISC-V-TLM is managed by Màrius Montón.

If you find this code useful, please consider citing:

@inproceedings{montonriscvtlm2020,
        title = {A {RISC}-{V} {SystemC}-{TLM} simulator},
        booktitle = {Workshop on {Computer} {Architecture} {Research} with {RISC}-{V} ({CARRV 2020}),
        author = {Montón, Màrius},
        year = {2020}
}

Publications

I've published a paper describing the RISC-V simulator in CARRV 2020 conference (pdf).

License

Copyright (C) 2018, 2019, 2020 Màrius Montón (@mariusmonton)

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.