Network Booting Ubuntu using iPXE and NFS

                                

Network Booting

Using iPXE & NFS

Network Booting is a cool technique to boot the operating system in your machine from the network rather than the local hard drive. For example, in the above picture on the right is a desktop machine that does not have any hard drive, on the left we have a laptop. From the laptop, we will serve an OS over the network and the desktop machine will boot & run the OS completely over the network. The router will create the local network and act as a DHCP server. We will use iPXE & NFS mechanisms to do this. if you are interested to learn about the process in depth you can follow this link https://networkboot.org/fundamentals/ 

We will boot the Ubuntu 16.04.3 desktop version so firstly download the OS from http://releases.ubuntu.com/ and extract it. I am sharing my hands-on experience so my paths won't exactly match yours. My Host machine, which is the laptop in this case, is also running Ubuntu 16.04.3 desktop edition. 

First, install the dependencies 

~/diskless-node-pxe-setup$ sudo apt-get install liblzma-dev

Git clone the iPXE project’s source 

~/diskless-node-pxe-setup$ git clone git://git.ipxe.org/ipxe.git

~/diskless-node-pxe-setup$cd ipxe/src

Build the ROM for USB [for initial build test, later we will make the actual ROM] 

~/diskless-node-pxe-setup/ipxe/src$ make bin/ipxe.usb

We will use the NFS service to serve the OS so our host machine needs to have it 

Install NFS kernel Server 

~$sudo apt-get install rpcbind nfs-kernel-server

Open this file using gedit 

~$sudo gedit /etc/exports

Write the path of the extracted OS at the bottom of the file 

/home/hassin/Downloads/ubuntu-16.04.3-desktop-amd64     *(ro,async,no_wdelay,insecure_locks,no_root_squash,insecure,no_subtree_check)

Add NFS support to the PXE ROM 

~/diskless-node-pxe-setup/ipxe/src$ echo "#define DOWNLOAD_PROTO_NFS" >> config/local/general.h

Add script support to the ROM 

Open this file “ipxe/src/config/local/general.h

The IMAGE_SCRIPT macro should be defined [ not commented out] 

Take note of your host machine IP,

~$ ifconfig

for my machine, it was 192.168.0.100 

Create a script 

~/diskless-node-pxe-setup/ipxe-scripts$ cat > ubuntu16-live.ipxe

Open the script 

~/diskless-node-pxe-setup/ipxe-scripts$ gedit ubuntu16-live.ipxe

Add the following lines 

echo Hi, trying to boot ubuntu16-live set server_ip 192.168.0.100 set nfs_path /home/ayx/Downloads/ubuntu-16.04.3-desktop-amd64 kernel nfs://${server_ip}${nfs_path}/casper/vmlinuz.efi || read void initrd nfs://${server_ip}${nfs_path}/casper/initrd.lz || read void imgargs vmlinuz.efi initrd=initrd.lz root=/dev/nfs boot=casper netboot=nfs nfsroot=${server_ip}:${nfs_path} ip=dhcp splash quiet -- || read void boot || read void echo Booting

Save it 

Now make the ROM by embedding the script 

~/diskless-node-pxe-setup/ipxe/src$ make bin/ipxe.usb EMBED=../../ipxe-scripts/ubuntu16-live.ipxe

Insert a pen drive, take note of its drive letter using the “Disks” utility app of ubuntu 

For my case, it was sdb 

~/diskless-node-pxe-setup/ipxe/src$ sudo dd if=bin/ipxe.usb of=/dev/sdb

Export the NFS shares of your host machine 

~$sudo exportfs -ra

Restart NFS-kernel-server 

~$sudo /etc/init.d/nfs-kernel-server restart

Remove the pen-drive , insert it into the desktop machine 

Make sure USB from the boot is enabled, 

Now everything okay then you will be able to use ubuntu over the network 

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P10(1R) Dot Matrix Display Interfacing With Arduino

 The dot matrix display that I have is P10(1R), 

Don’t worry about the upper section being empty, I later did program it to show text 

Actual display Board	Back Part [ PCB ]

It is P10(1R)-DP4 536-V5 Type 

The closest datasheet that I got for this is http://www.hlec.com.cn/userfiles/files/20120928014657.pdf 

These Large Display Boards have multiple Units cascaded together. I call each unit a Panel 

So Multiple Panels being chained together make a large display board 

Here is how my board and it panels are chained to form the large display 

The Blue colored Double lines are the long jumper wires that chains each panel with another 

Now here is more info related to the Display 

• Pixels per Panel is 32 (W)*16 (H) dots 

• The board has 4 panels per chain 

• The board has 2 chains 

• So 8 panels in total 

• So the total resolution is 320(w)x32(h) 

The pin interface is called HUB12, I have interfaced it with Arduino Uno 

Marking on the PCB	HUB12 pinout at the datasheet	Arduino Uno Pin Interface

Here is where How you should connect Arduino Uno with the Display 

So you connect the Arduino Uno to the HUB12 interface to the panel located at [0,0] position 

Notice Panel 4 is chained to Panel 5 HUB12 interface by long jumper wire 

The Connection between HUB12 and Arduino Uno is 

Ref: http://cdn.shopify.com/s/files/1/0045/8932/files/DMDCON_DMDConnector.pdf?100730 

HUB12	Arduino
nOE	9
A	6
B	7
CLK	13
SCLK	8
R_DATA	11
GND	GND

MOST Important: Use an External power Supply like this to power up the Display Board. Arduino is just for applying the logic. Don’t ever think it can power up the display board 😄

Now let’s prepare the Arduino Code 

At first, we have to install the libraries 

1. Download this library https://github.com/freetronics/DMD 

Extract it and copy it to the Arduino libraries folder for example in my case   “/home/ayx/Arduino/libraries” 

     

     2. Open Arduino IDE and Install “TImerOne” Library using the “manage libraries” option 

Open Dmd_demo.ino sketch 

Change The code snippet like this 

//SPI.h must be included as DMD is written by SPI #include <SPI.h>        #include <DMD.h>        #include <TimerOne.h>   #include "SystemFont5x7.h" #include "Arial_black_16.h" #include "Droid_Sans_24.h" //Fire up the DMD library as dmd #define DISPLAYS_ACROSS 4 #define DISPLAYS_DOWN 2 DMD dmd(DISPLAYS_ACROSS, DISPLAYS_DOWN); void ScanDMD() {   dmd.scanDisplayBySPI(); } void setup(void) {   Timer1.initialize( 3000 );//period in microseconds to call ScanDMD.   Timer1.attachInterrupt( ScanDMD );//attach the Timer1 interrupt to scan   dmd.clearScreen( true );    //clearthe DMD pixels held in RAM   dmd.selectFont(Droid_Sans_24); } void loop(void) {   dmd.clearScreen( true );   delay(2000);   dmd.drawMarquee("Scrolling Text",14,(32*DISPLAYS_ACROSS)-1,6); }

Compile it and upload you, if everything is okay then you will see a large text scrolling 

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