README.md

   1 <p align="center">
   2 <img src="media/microwatt-title.png" alt="Microwatt">
   3 </p>
   4
   5 # Microwatt
   6
   7 A tiny Open POWER ISA softcore written in VHDL 2008. It aims to be simple and easy
   8 to understand.
   9
  10 ## Simulation using ghdl
  11 <p align="center">
  12 <img src="http://neuling.org/microwatt-micropython.gif" alt="MicroPython running on Microwatt"/>
  13 </p>
  14
  15 You can try out Microwatt/Micropython without hardware by using the ghdl simulator. If you want to build directly for a hardware target board, see below.
  16
  17 - Build micropython. If you aren't building on a ppc64le box you
  18   will need a cross compiler. If it isn't available on your distro
  19   grab the powerpc64le-power8 toolchain from https://toolchains.bootlin.com
  20
  21 ```
  22 git clone https://github.com/micropython/micropython.git
  23 cd micropython
  24 cd ports/powerpc
  25 make -j$(nproc)
  26 cd ../../../
  27 ```
  28
  29   A prebuilt micropython image is also available in the micropython/ directory.
  30
  31 - Microwatt uses ghdl for simulation. Either install this from your
  32   distro or build it. Microwatt requires ghdl to be built with the LLVM
  33   or gcc backend, which not all distros do (Fedora does, Debian/Ubuntu
  34   appears not to). ghdl with the LLVM backend is likely easier to build.
  35
  36   If building ghdl from scratch is too much for you, the microwatt Makefile
  37   supports using Docker or podman images. Read through the Makefile for details.
  38
  39 - Next build microwatt:
  40
  41 ```
  42 git clone https://github.com/antonblanchard/microwatt
  43 cd microwatt
  44 make
  45 ```
  46
  47 - Link in the micropython image:
  48
  49 ```
  50 ln -s ../micropython/ports/powerpc/build/firmware.bin main_ram.bin
  51 ```
  52
  53   Or if you were using the pre-built image:
  54
  55 ```
  56 ln -s micropython/firmware.bin main_ram.bin
  57 ```
  58
  59 - Now run microwatt, sending debug output to /dev/null:
  60
  61 ```
  62 ./core_tb > /dev/null
  63 ```
  64
  65 ## Synthesis on Xilinx FPGAs using Vivado
  66
  67 - Install Vivado (I'm using the free 2019.1 webpack edition).
  68
  69 - Setup Vivado paths:
  70
  71 ```
  72 source /opt/Xilinx/Vivado/2019.1/settings64.sh
  73 ```
  74
  75 - Install FuseSoC:
  76
  77 ```
  78 pip3 install --user -U fusesoc
  79 ```
  80 Fedora users can get FuseSoC package via
  81 ```
  82 sudo dnf copr enable sharkcz/danny
  83 sudo dnf install fusesoc
  84 ```
  85
  86 - Create a working directory and point FuseSoC at microwatt:
  87
  88 ```
  89 mkdir microwatt-fusesoc
  90 cd microwatt-fusesoc
  91 fusesoc library add microwatt /path/to/microwatt/
  92 ```
  93
  94 - Build using FuseSoC. For hello world (Replace nexys_video with your FPGA board such as --target=arty_a7-100):
  95
  96 ```
  97 fusesoc run --target=nexys_video microwatt --memory_size=16384 --ram_init_file=/path/to/microwatt/fpga/hello_world.hex
  98 ```
  99 You should then be able to see output via the serial port of the board (/dev/ttyUSB1, 115200 for example assuming standard clock speeds). There is a know bug where initial output may not be sent - try the reset (not programming button) on your board if you don't see anything.
 100
 101 - To build micropython (currently requires 1MB of BRAM eg an Artix-7 A200):
 102
 103 ```
 104 fusesoc run --target=nexys_video microwatt
 105 ```
 106
 107 ## Testing
 108
 109 - A simple test suite containing random execution test cases and a couple of
 110   micropython test cases can be run with:
 111
 112 ```
 113 make -j$(nproc) check
 114 ```
 115
 116 ## Issues
 117
 118 This is functional, but very simple. We still have quite a lot to do:
 119
 120 - There are a few instructions still to be implemented
 121 - Need to add caches and bypassing (in progress)
 122 - Need to add supervisor state (in progress)