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147 lines
3.8 KiB
Markdown
147 lines
3.8 KiB
Markdown
<p align="center">
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<img src="media/microwatt-title.png" alt="Microwatt">
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</p>
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# Microwatt
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A tiny Open POWER ISA softcore written in VHDL 2008. It aims to be simple and easy
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to understand.
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## Simulation using ghdl
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<p align="center">
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<img src="http://neuling.org/microwatt-micropython.gif" alt="MicroPython running on Microwatt"/>
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</p>
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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.
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- Build micropython. If you aren't building on a ppc64le box you
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will need a cross compiler. If it isn't available on your distro
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grab the powerpc64le-power8 toolchain from https://toolchains.bootlin.com.
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You may need to set the CROSS_COMPILE environment variable
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to the prefix used for your cross compilers. The default is
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powerpc64le-linux-gnu-.
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```
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git clone https://github.com/micropython/micropython.git
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cd micropython
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cd ports/powerpc
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make -j$(nproc)
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cd ../../../
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```
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A prebuilt micropython image is also available in the micropython/ directory.
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- Microwatt uses ghdl for simulation. Either install this from your
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distro or build it. Microwatt requires ghdl to be built with the LLVM
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or gcc backend, which not all distros do (Fedora does, Debian/Ubuntu
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appears not to). ghdl with the LLVM backend is likely easier to build.
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If building ghdl from scratch is too much for you, the microwatt Makefile
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supports using Docker or Podman.
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- Next build microwatt:
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```
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git clone https://github.com/antonblanchard/microwatt
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cd microwatt
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make
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```
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To build using Docker:
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```
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make DOCKER=1
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```
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and to build using Podman:
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```
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make PODMAN=1
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```
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- Link in the micropython image:
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```
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ln -s ../micropython/ports/powerpc/build/firmware.bin main_ram.bin
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```
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Or if you were using the pre-built image:
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```
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ln -s micropython/firmware.bin main_ram.bin
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```
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- Now run microwatt, sending debug output to /dev/null:
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```
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./core_tb > /dev/null
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```
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## Synthesis on Xilinx FPGAs using Vivado
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- Install Vivado (I'm using the free 2019.1 webpack edition).
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- Setup Vivado paths:
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```
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source /opt/Xilinx/Vivado/2019.1/settings64.sh
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```
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- Install FuseSoC:
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```
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pip3 install --user -U fusesoc
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```
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Fedora users can get FuseSoC package via
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```
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sudo dnf copr enable sharkcz/danny
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sudo dnf install fusesoc
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```
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- If this is your first time using fusesoc, initialize fusesoc.
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This is needed to be able to pull down fussoc library components referenced
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by microwatt. Run
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```
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fusesoc init
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```
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- Create a working directory and point FuseSoC at microwatt:
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```
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mkdir microwatt-fusesoc
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cd microwatt-fusesoc
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fusesoc library add microwatt /path/to/microwatt/
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```
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- Build using FuseSoC. For hello world (Replace nexys_video with your FPGA board such as --target=arty_a7-100):
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You may wish to ensure you have [installed Digilent Board files](https://reference.digilentinc.com/vivado/installing-vivado/start#installing_digilent_board_files)
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or appropriate files for your board first.
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```
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fusesoc run --target=nexys_video microwatt --memory_size=16384 --ram_init_file=/path/to/microwatt/fpga/hello_world.hex
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```
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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.
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- To build micropython (currently requires 1MB of BRAM eg an Artix-7 A200):
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```
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fusesoc run --target=nexys_video microwatt
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```
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## Testing
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- A simple test suite containing random execution test cases and a couple of
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micropython test cases can be run with:
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```
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make -j$(nproc) check
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```
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## Issues
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This is functional, but very simple. We still have quite a lot to do:
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- There are a few instructions still to be implemented
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- Need to add caches and bypassing (in progress)
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- Need to add supervisor state (in progress)
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