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ARM32 64isa

Comparison between ARM 32 bit and ARM 64-bit instruction sets and performances on a Raspberry Pi 3 model B.

To compare the two different instruction sets and performances we decided to implement different programs:

• secure hash algorithm (SHA) in its two variants SHA256(32 bit) and SHA512(64 bit)
• programs that interact with input and output through the GPIO

Setup

First of all, it is necessary to install two different operating systems on the Raspberry Pi, one working at 32 bits and one at 64 bits. It's recommended to use two different SD cards.

We decided to install Raspbian as our 32 bit OS, you can find it on the official website of Raspberry Pi.

For the 64 bit OS, we decided to install Gentoo. The Bootable 64-bit Gentoo image for the Raspberry Pi 3, a step by step guide for its installation and the full documentation can be found at this Github repository.

When the boot is completed, you should verify to have on your OS a working version of the GNU Project Debugger (GDB) for debugging purposes.

To work with the Raspberry Pi you could simply attach it to a monitor, a mouse and a keyboard but we found it easier to work with it remotely from our laptop.

Working remotely with the Raspberry Pi

To work remotely with our board, we had to link it with an ethernet cable to a modem; in this way, we were able to access it exploiting the network protocol SSH. If you use Linux you can use this protocol directly from the command line (ssh username@remoteIP), while if you are on Windows you can download PuTTY, an SSH and telnet client. The default username and password can be found in the documentation of the OS running on the board (Rasbian: username=pi pwd=raspberry; Gentoo: username=demouser pwd=raspberrypi64).
Moreover, you have to verify that SSH is enabled on your Raspberry Pi (for example it's disabled by default on Rasbian). You also have to find the IP address of the device and to do so we used an android app, fing. Since we decided to work remotely we exploited the SSH file transfer protocol to transfer files from our laptops to the board, using a sftp client (FileZilla), an alternative would be to exploit a command line text editor.