Running Microwatt on Ubuntu 20.04

What is Microwatt?

You probably know already :)

IBM recently made their POWER ISA open sourced with a very liberal license. OpenPOWER Foundation joined the Linux Foundation in August 2019 and in the same month Microwatt was released to the community.

Microwatt is a VHDL2008-based POWER ISA 3.0 core, originally written by Anton Blanchard, supporting Linux, MicroPython and Zephyr RTOS.

It is also supported in FuseSoC for quick simulation and FPGA bringup!

Installation on Ubuntu 20.04

• The GitHub repo for Microwatt does give instructions in short and also a cute little GIF showing 1+2 = 3 ;)

• It does have pointers to what you need to set up on non-POWER (say x86) systems to get it running, you would still need some digging around.

• I was able to successfully get simulations running on Ubuntu 20.04 and decided to list down the steps here:

• I also made ans ASCII cinema for this process - which completes this whole process in 8 mins! - https://asciinema.org/a/364414

• (Note that if you are on a different Ubuntu release, there might be small changes needed here and there) Make a new directory wherever you like

  1 2	mkdir /home/$USER/uwatt cd /home/$USER/uwatt

  1. Download PowerPC cross toolchain
     • You can select powerpc64le-power8 and glibc on toolchains.bootlin.com or get the stable version as of date directly with

       1 2	wget https://toolchains.bootlin.com/downloads/releases/toolchains/powerpc64le-power8/tarballs/powerpc64le-power8--glibc--stable-2020.02-2.tar.bz2 tar -xvf powerpc64le-power8--glibc--stable-2020.02-2.tar.bz2

     • Since this is a prebuilt toolchain, all you need to use it is

       1 2	export PATH=$PATH:/home/$USER/uwatt/powerpc64le-power8--glibc--stable-2020.02-2/bin export CROSS_COMPILE=powerpc64le-linux-

  2. Build Micropython

     1 2 3 4 5

     git clone https://github.com/micropython/micropython.git cd micropython/ports/powerpc sudo apt install make make -j$(nproc) cd ../../../

  3. Build GHDL from source
     • Install LLVM, Clang, zlib

       1	sudo apt install llvm clang gnat zlib1g-dev

     • Install gnat4.9 packages (needed by GHDL):

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       wget http://archive.ubuntu.com/ubuntu/pool/universe/g/gnat-4.9/gnat-4.9-base_4.9.3-3ubuntu5_amd64.deb wget http://archive.ubuntu.com/ubuntu/pool/universe/g/gnat-4.9/libgnat-4.9_4.9.3-3ubuntu5_amd64.deb sudo dpkg -i ./gnat-4.9-base_4.9.3-3ubuntu5_amd64.deb sudo dpkg -i ./libgnat-4.9_4.9.3-3ubuntu5_amd64.deb

     • Clone and build GHDL from GitHub (ideally you should go for a stable release, but v0.37 does not support llvm10, in which case you will need to specify older version of llvm above. The master branch doesn’t seem to have this issue.)

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       git clone https://github.com/ghdl/ghdl.git cd ghdl mkdir -p /home/$USER/uwatt/ghdl_build mkdir build && cd build ../configure --with-llvm-config --prefix=/home/$USER/uwatt/ghdl_build make make install cd ../../

     • If you face dependency issues, Google would mostly help. In case you realise that a package is not available in focal repositories, you can try the wget and deb method (similar to gnat above)
     • After building, add ghdl to path with

       1	export PATH=$PATH:/home/$USER/uwatt/ghdl_build/bin

  4. Build Microwatt

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     git clone https://github.com/antonblanchard/microwatt cd microwatt make

  5. Link Micropython image (note that here we are using pre-built image inside microwatt repository. At least on my system, I am not able to provide inputs to the micropython terminal with the image built above. This issue has been reported on microwatt GitHub - https://github.com/antonblanchard/microwatt/issues/246)

     1	ln -s micropython/firmware.bin main_ram.bin

  6. Run Microwatt! (By sending output logs to /dev/null, you can also specify a file name if needed)

     1	./core_tb > /dev/null

     Note that this is similar to running a Python interpreter shell on your local system, but here the execution is through simulation mechanism.

  7. (Optional) Run bare-metal C code on Microwatt! By this method, you can write simple C test programs and check their operation. This is achieved by compiling them using the GCC cross-compiler. a. I have made changes to the Makefile in hello_world directory to allow any filename and linking main_ram.bin with compiled binary in single step. First try running the existing hello_world example.

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     cd ~/uwatt/microwatt/hello_world wget https://pastebin.com/raw/2WdH5Z4d -O Makefile make

     b. Try cd .. and ./core_tb > /dev/null and you would be greeted by Microwatt :)

     1 2 3 4 5 6 7 8

     .oOOo. ." ". ; .mw. ; Microwatt, it works. . ' ' . \ || / ;..; ;..; `ww'

     c. Now you can go and modify hello_world.c or even create a new file say shivam_test.c (retain the includes and console_init lines). To run this new file

     1 2	make clean make FILE=shivam_test

     d. Here is an example of printing sum of 1 to 10 using C:

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     #include <stdint.h> #include <stdbool.h> #include "console.h" void iprint(int n) { if (n/10) iprint(n/10); putchar(n%10 + '0'); } int main(void) { console_init(); int i = 0, sum=0; for(i;i<=10;i++) { sum += i; iprint(sum); putchar(10); } puts("Shivam"); }

     Output:

     1 2 3 4 5 6 7 8 9 10 11 12

     0 1 3 6 10 15 21 28 36 45 55 Shivam

That’s all folks! :)