Work Environment
NAS: Synology DS216+II with DSM 6.1.7-15284
Netgear WNDR3700v2 Router Running Gargoyle Firmware version 1.10.0 or DD-WRT v3.0-r40559 std (08/06/19)
Raspberry Pi
Before you begin
If you have a battery backup unit then enable UPS.
To boot a Raspberry Pi 4 using PXE, there are a few steps required, starting with updating that bootloader firmware. This means installing Raspbian to an SD card and booting the Pi off of it at least once. From there, we turn to the PXE server to build the remote filesystem and set up the NFS and dnsmasq services. This article draws from a pair of official Pi network boot guides.
Bootloader Update
At the time of writing, the eeprom firmware that supports PXE boot is still in beta. We have to grab that firmware, change the boot order configuration, and then flash it to the onboard chip. Once the Pi 4 is booted off your Raspbian SD card, we can do the following to get the firmware updated:
$ sudo apt-get update $ sudo apt-get upgrade $ wget https://github.com/raspberrypi/rpi-eeprom/raw/master/firmware/beta/pieeprom-2019-10-16.bin $ rpi-eeprom-config pieeprom-2019-10-16.bin > bootconf.txt $ sed -i s/0x1/0x21/g bootconf.txt $ rpi-eeprom-config --out pieeprom-2019-10-16-netboot.bin --config bootconf.txt pieeprom-2019-10-16.bin $ sudo rpi-eeprom-update -d -f ./pieeprom-2019-10-16-netboot.bin $ cat /proc/cpuinfo
That last command should output some information on the Pi itself. We’re interested in the entry for the Pi’s serial number. Write down the last 8 characters of that code, as we’ll use it later. That’s all the setup needed for the Pi itself.
Download Raspbian Lite ZIP file and extract the image.
If your router acts as the DHCP server in your network then it will need to support network booting (most do not) if you want to continue to use it as the DHCP server, otherwise you will need to disable DHCP on your router and setup a DHCP server on your NAS. An alternative is to install a Linux firmware to your router if it’s possible (i.e. OpenWRT, DD-WRT, etc.) which is the scenario used for this guide.