Network boot a bunch of Raspberry Pi 3
======================================

Assumptions
-----------

* Installed OS on server: Debian
* Installed OS on clients: Raspbian
* bootcode.bin installed on each SD-Card

Prerequisites
-------------

* Install packages on server::

    dnsmasq nfs-kernel-server tcpdump

* Modify the common cmdline.txt::

    dwc_otg.lpm_enable=0 console=serial0,115200 console=tty1 root=/dev/nfs \
    nfsroot=<server-ip>:/<nfs-root>,udp,nfsvers=3,rsize=32768,wsize=32768, \
    hard,intr rw ip=dhcp rootwait elevator=deadline

  With the following parameters:

  * server-ip: The IP address of your NFS server
  * nfs-root: The root directory of the exported NFS filesystem

  .. note:: Use the nfsvers/rsize/wsize parameters for higher speed.

* Put a copy of the complete /boot directory of a raspbian install into a
  directory with the name /tftpboot/rpi.

* Add to /etc/dnsmasq.conf::

    port=0
    dhcp-range=<ip-range>,proxy
    log-dhcp
    enable-tftp
    tftp-root=/tftpboot
    pxe-service=0,"Raspberry Pi Boot   "
    dhcp-ignore=tag:!known
    dhcp-host=<mac-address>,<ip-address>
    dhcp-host=b8:27:eb:82:8f:f4,140.181.65.134 #landpi003

  With the following parameters:

  * ip-range: Range of IP addresses to listen to (e.g. 192.168.1.255)
  * mac-address: MAC address of client
  * ip-address: IP address of client


  .. note:: Make sure to include the three spaces in the pxe-service name.
            Add one 'dhcp-host' line per managed client.

* Modify /etc/exports::

    # Example export for network-booted raspberry pis
    /nfs/rpi *(rw,sync,no_subtree_check,no_root_squash)

  This location contains the complete / tree of a raspbian install.

Prepare raspberry pi
--------------------

* Program usb boot mode using the original SD-Card image::

    sudo su
    apt-get update
    apt-get install rpi-update
    BRANCH=next rpi-update
    echo program_usb_boot_mode=1 >> /boot/config.txt
    reboot

* Check that this was successful::

    vcgencmd otp_dump | grep 17
    Should yield: 17:3020000a

  Remove the program_usb_boot_mode=1 line from /boot/config.txt

Prepare SD-card
---------------

* Copy bootcode.bin from 'next' branch of rpi-update (hexxeh) to an
  otherwise empty SD-card::

    cfdisk /dev/mmcblk0 # Delete all partitions, and create a new one.
    sudo mkfs.vfat /dev/mmcblk0p1
    mount /dev/mmcblk0p1 /mnt
    wget https://github.com/Hexxeh/rpi-firmware/raw/next/bootcode.bin
    cp bootcode.bin /mnt

  Assuming that your SD-card is mounted as mmcblk0.

Prepare server
--------------

* Start watching for bootpc requests from raspberrypi::

    tcpdump -i eth0 port bootpc | grep b8:27

* Add a line to /etc/dnsmasq.conf::

    dhcp-host=<mac-address>,<ip-address> #<hostname>
    Example:
    dhcp-host=b8:27:eb:12:3b:4c,192.168.1.3 #raspberrypi003

* On the server start a watcher on tftp-requests::

    sudo tail -f /var/log/syslog | grep tftp

  Watch for lines like::

    dnsmasq-tftp[5790]: file /tftpboot/<serial-number>/start.elf not found

  Write down <serial-number>

* Create a symbolic link for this serial number::

    cd /tftpboot
    ln -s rpi <serial-number>

  /tftpboot/rpi contains all /boot files (see above)

* Modify /nfs/rpi/etc/rc.local::

    Add a line after # Set hostname based on serial number
    test ${_SN} == "<serial-number>" && hname=<hostname>

* Copy the var directory::

    cd /nfs/rpi
    cp -r rpi <serial-number>

* Reboot the raspberrypi
  It should come up now and boot from the server.
  You should be able to log in via ssh