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   You may need to set the CROSS_COMPILE environment variable
  21   to the prefix used for your cross compilers.  The default is
  22   powerpc64le-linux-gnu-.
  23
  24 ```
  25 git clone https://github.com/micropython/micropython.git
  26 cd micropython
  27 cd ports/powerpc
  28 make -j$(nproc)
  29 cd ../../../
  30 ```
  31
  32   A prebuilt micropython image is also available in the micropython/ directory.
  33
  34 - Microwatt uses ghdl for simulation. Either install this from your
  35   distro or build it. Microwatt requires ghdl to be built with the LLVM
  36   or gcc backend, which not all distros do (Fedora does, Debian/Ubuntu
  37   appears not to). ghdl with the LLVM backend is likely easier to build.
  38
  39   If building ghdl from scratch is too much for you, the microwatt Makefile
  40   supports using Docker or podman images. Read through the Makefile for details.
  41
  42 - Next build microwatt:
  43
  44 ```
  45 git clone https://github.com/antonblanchard/microwatt
  46 cd microwatt
  47 make
  48 ```
  49
  50 - Link in the micropython image:
  51
  52 ```
  53 ln -s ../micropython/ports/powerpc/build/firmware.bin main_ram.bin
  54 ```
  55
  56   Or if you were using the pre-built image:
  57
  58 ```
  59 ln -s micropython/firmware.bin main_ram.bin
  60 ```
  61
  62 - Now run microwatt, sending debug output to /dev/null:
  63
  64 ```
  65 ./core_tb > /dev/null
  66 ```
  67
  68 ## Synthesis on Xilinx FPGAs using Vivado
  69
  70 - Install Vivado (I'm using the free 2019.1 webpack edition).
  71
  72 - Setup Vivado paths:
  73
  74 ```
  75 source /opt/Xilinx/Vivado/2019.1/settings64.sh
  76 ```
  77
  78 - Install FuseSoC:
  79
  80 ```
  81 pip3 install --user -U fusesoc
  82 ```
  83 Fedora users can get FuseSoC package via
  84 ```
  85 sudo dnf copr enable sharkcz/danny
  86 sudo dnf install fusesoc
  87 ```
  88
  89 - Create a working directory and point FuseSoC at microwatt:
  90
  91 ```
  92 mkdir microwatt-fusesoc
  93 cd microwatt-fusesoc
  94 fusesoc library add microwatt /path/to/microwatt/
  95 ```
  96
  97 - Build using FuseSoC. For hello world (Replace nexys_video with your FPGA board such as --target=arty_a7-100):
  98
  99 ```
 100 fusesoc run --target=nexys_video microwatt --memory_size=16384 --ram_init_file=/path/to/microwatt/fpga/hello_world.hex
 101 ```
 102 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.
 103
 104 - To build micropython (currently requires 1MB of BRAM eg an Artix-7 A200):
 105
 106 ```
 107 fusesoc run --target=nexys_video microwatt
 108 ```
 109
 110 ## Testing
 111
 112 - A simple test suite containing random execution test cases and a couple of
 113   micropython test cases can be run with:
 114
 115 ```
 116 make -j$(nproc) check
 117 ```
 118
 119 ## Issues
 120
 121 This is functional, but very simple. We still have quite a lot to do:
 122
 123 - There are a few instructions still to be implemented
 124 - Need to add caches and bypassing (in progress)
 125 - Need to add supervisor state (in progress)