The DHCP protocol has 4 parts for our interest: Port 67 is for client -> server packets and 68 is for the other way around s0 do not truncate packet and show full content To enable PXE boot, we first need to figure out what options Pi is asking for. The command should be more or less the same for anything using OpenWRT. Now it comes to the router side as we need to enable the extra options of DHCP such that Pi can find the NAS in the same network. Now it should be stuck on the initial self test screen as it can neither boot from SD or net. Unplug, remove the SD card and replug the Pi. Sudo rpi-eeprom-update -d -f bootloader.binīefore exiting, grab the serial number: 1Ĭat /proc/cpuinfo | grep Serial | tail -c 9Īssume this is 123456789. ![]() Sudo rpi-eeprom-config -out bootloader.bin -config bootconf.txt pieeprom-.bin Sed -i 's/BOOT_ORDER=.*/BOOT_ORDER=0xf21/g' bootconf.txt Sudo rpi-eeprom-config pieeprom-.bin > bootconf.txt For example to grab version: 1Įxtract the bootconf.txt file and update order: 1 To do that, first we need to grab a bootloader that supports netboot. The full doc about order can be found here. We’ll change this to 0xf21 (SD -> Network -> restart). The default is 0x1 (or 0xf41 in later version) which means it’s SD card only (or SD -> USB -> restart). The boot order is a sequence of digits from right to left. Vcgencmd bootloader_config | grep BOOT_ORDER | cut -d '=' -f 2 The default user name and password is pi and raspberry. For headless setup, don’t forget to touch ssh to create the file to enable ssh by default. Here we need a small microSD card to flash the Raspberry Pi OS onto it and boot the system. Technically it should be doable if they are shipped with the right “stuff” but I decide not to waste more time figuring out what the “stuff” is. Yes the vcgencmd binary does not work in Ubuntu or any other “supported” Linux distros, even if you compile from source. Pitfall #1: vcgencmd can only work in native Raspberry Pi OS This also requires using the raspberry cli binary vcgencmd. To do that, we need to grab the updated version of bootcode.bin file which supports netboot and update the config. With the basic knowledge equipped, we can continue by first enabling the netboot in bootloader. The kernel will later be loaded which takes over the boot process and eventually loads the rest of the system distribution. This is important as certain config (like cmdline.txt) would tell the OS how to mount the root fs and thus needs to be separate. By default, that’s the last 9 chars of the serial number. The bootloader has a config to specify the exact path for the current device. Once enabled, upon powering up, Pi will first send a DHCP request to ask for the TFTP server location and verify if netboot is supported.Īfter that it will fetch the firmware (start4.elf), configs and kernel files (vmlinuz) from that tftp location. The bootloader in EEPROM by default does not enable netboot so we’d need to enable that first. But for newer version of NAS it might be possible. ![]() Due to kernel limitation, my NAS cannot support overlayfs. The Synology NAS will be serving data via tftp (pxe boot) and nfs (post boot). ![]() The Ubiquiti will also be serving as the DHCP server. Here’s a diagram of the network topology I use for the setup: One thing worth noting is that even though this post mentions “PXE” and so does the official document, the boot process isn’t entirely PXE compliant and thus regular PXE boot support setup process may not work at all or at least not directly. However, the entire setup process is not that straightforward and it’s thus worth writing down all the pitfalls through the path especially when it involves a non-“native” Linux distribution. Sorry – but we no longer include images for Berryboot for the latest versions.Raspberry Pi 4 is shipped with a flashable EEPROM and supports netbooting.
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