FSOSS 2010 Plug Computing Workshop

This page outlines the Plug Computing workshop held at FSOSS 2010 - Thursday, October 28, 2010, room T2108.

ARM Chips, Plug Computers, and Fedora, Oh My!

The ARM Processor

ARM CPUs were originally created as 32-bit desktop RISC processors. They have become highly valued as low-power-consumption processors, and are widely used in cellphones, tablets, and embedded systems; over 5 billion ARM devices are now manufactured anually.

ARM Ltd. does not actually produce any physical chips -- they license the designs to various chipmakers, who then incorporate them into their products, often integrating other peripherals in the process -- peripherals such as camera controllers, network interfaces, or cellphone logic. ARM licensees include Marvell, Texas Instruments, Samsung, Freescale, and many others.

Plug Computing

The PlugComputing concept was created by Marvell to promote the use of ARM processors in non-mobile environments -- as a power-saving server option. Each PlugComputer contains a Marvell system-on-a-chip (SOC) and flash-based storage.

The model of PlugComputer we're using today is the GuruPlug Server Plus, made by GlobalScale Technologies, Inc. This unit features 512MB of RAM, 512MB of built-in NAND flash, support for microSD/microSDHC cards, dual gigabit ethernet interfaces, eSATA, two USB ports, 802.11bg wireless, and bluetooth. The total power consumption of the GuruPlug is typically under 5W - about the power of a small nightlight.

Fedora

The Fedora Project is a community sponsored by Red Hat which produces a Linux distribution. The Fedora distribution is typically used on 32- and 64-bit Intel/AMD-compatible processors, which are known as the "Primary Architectures". However, there are a number of special interest groups within Fedora which compile the distribution for use on other processors, including SPARC, MIPS, IBM mainframe (Z9), and ARM systems.

Fedora software is maintained as a large collection of separate packages -- over 15,000 at the present time. These packages can be combined in various combinations to meet different needs (desktop, server, mobile).

Fedora utilizes a client-server based build system which permits any package

Setting up the GuruPlug

Before you can use the GuruPlug for useful work, you need to install Fedora on a microSD flash memory card, verify that it boots properly, and connect it to the network.

Getting the Root Filesystem Image

1. Download this file and save it on your local disk: http://australia.senecac.on.ca/fsoss/rootfs-f12.tar.bz2

Copying the rootfs to the microSD Card

1. Remove the microSD card from the GuruPlug.
2. Insert the card into the card reader on your PC. A window should appear; it is OK to leave this window open.
3. Open a terminal window (menu option Applications>System Tools>Terminal).
4. Request administrator/superuser privilege by typing: su
5. Change to the directory containing the microSD card: cd /media/*
6. Erase everything on the card (type this command very carefully!): rm -rf /media/*/*
7. Unpack the rootfs onto the microSD card: tar xvf ~fsoss/Downloads/rootfs-f12.tar.bz2
8. The files have been unpacked into a directory named rootfs-12. Move them out of that directory: mv rootfs-f12/* .

Preparing the rootfs Image: Turning On the Lights

Since the GuruPlug doesn't have a screen, it's hard to know if the system has booted properly. Fortunately, the GuruPlug has LEDs on it, and we can use those LEDs to check that the system is booting properly. The Linux kernel has direct device support for the LEDs, and they can be set to flash at various rates; indicate disk, flash memory, or wireless activity; or show a heartbeat pattern (double flash, indicating that the system is running).

Let's program the red LEDs to show a heartbeat when the system is booted.

1. Change to the directory containing the startup scripts: cd /media/*/etc/rc.d
2. Add code to the rc.local script to flash the lights:

for LAMP in /sys/class/leds/*/trigger
do
        echo heartbeat >$LAMP
done

Try it!

1. Umount the microSD card.
2. Remove the card from your PC.
3. Insert the card into your GuruPlug.
4. Remove the GuruPlug power cable connector.
5. Attach the GuruPlug power prongs.
6. Plug the GuruPlug into a power jack.
7. Give it some time to boot up.
8. If the red LEDs are flashing, success! (If not, find out what's going wrong and fix it).

Plug your Plug into the Network

1. Remove the GuruPlug power prongs.
2. Re-attach the GuruPlug power cable connector.
3. Add your GuruPlug into the network shelves at the front of the room.

Connect to your GuruPlug

To connect to your plug over the network, you'll need to connect to the computer managing the GuruPlug cluster, which is named "HongKong".

1. Connect to HongKong: ssh -XC hongkong (password is "fsoss10")
2. Connect to your plug: ssh nameOfYourPlug