Lord of the rings: MESI & cache coherence

Fabián Montero, Alejandro Soto, Julián Camacho

Introduction

This is a quad-core soft processor that implements ARMv4 with 64kb cache in each core with no shared cache. It is implemented in a DE-SoC-1 Altera FPGA.

In order to make ARMv4 capable of multicore, ldrex and strexeq were also implemented.

Getting started

There are two main components in this project. The soft core and software tests and simulations that simulate and can be executed in it.

Prerequisites

• An SD card flashed with a Terasic image for the DE-SoC-1 Altera FPGA available at: https://www.terasic.com.tw/en/

• Nix package manager version > 2.4 with flakes enabled. All other requirements will be installed by Nix. In order to initiate this process, cd into the root of the project and run the following command:

  nix develop

Building and loading the bitstream

In order to build the soft core, run quartus:

quartus

and open the conspiracion.qpf project file.

Once the project is loaded, open Platform Designer and Generate HDL. Close Platform Designer and Compile Design, this may take up to 40 mins.

Now click File->Generate Programming Files and use the following settings:

• Type: Raw Binary File (.rbf)
• Mode: Passive Parallel x16
• Change output_file.rbf to output_files/conspiracion.rbf
• In the Input files to convrert section, click Page_0 -> Add files -> Output_files/conspiracion.sof
• Click Generate

In your terminal, run nix develop if you hadn't already and run:

make demo.bin

Notice the printed path.

Plug in your SD card and mount it's /boot partition and create a directory called taller inside it. Copy the contents of the printed path into this directory, renaming it to boot.bin:

cp </printed/path> </path/to/mounted/boot/dir>/taller/boot.bin

Copy the output_files/conspiracion.rbf into taller:

cp </path/to/the/project/output_files/conspiracion.rbf> </path/to/mounted/boot/dir>/taller/

Unmount your SD card and plug it into the FPGA.

In order to boot:

• Turn off the reset switch
• In your terminal, run: kermit hps-fpga.kermit
• Power the FPGA on
• Wait for uBoot and Linux to boot
• In another terminal, run scrripts/jtag_uart.sh
• Turn on the reset switch

Done! :)