Configure Bootloader for Network Booting a Pi 4

configure-bootloader.sh

cp /lib/firmware/raspberrypi/bootloader/stable/pieeprom-2020-04-16.bin pieeprom.bin
rpi-eeprom-config pieeprom.bin > bootconf.txt

# Enable pxe booting, and copy over additions.
sed -i -r -e 's/BOOT_ORDER.*?$/BOOT_ORDER=0x21/g' bootconf.txt

# Set prefix to be the mac address, like normal PXE things.
TFTP_IP=$(cat /etc/iscsi/iscsi.initramfs | grep 'ISCSI_TARGET_IP=' | cut -d '=' -f 2)
sed -i -r -e 's/TFTP_PREFIX.*?$/TFTP_PREFIX=2/g' bootconf.txt

# Set the TFTP IP address (no need to mess with DHCP settings).
sed -i -r -e "s/TFTP_IP.*?$/TFTP_IP=${TFTP_IP}/g" bootconf.txt

# Set this device's IP address.
PI_IP=$(ifconfig eth0 | awk '/inet /{ print $2;}')
PI_NETMASK=$(ifconfig eth0 | awk '/netmask/{ print $4;}')
sed -i -r -e "s/^\[none\]$/CLIENT_IP=${PI_IP}\nSUBNET=${PI_NETMASK}\n[none]/g" bootconf.txt

# Save the new configuration to the firmware, and install it (requires a reboot).
rpi-eeprom-config --out pieeprom-netboot.bin --config bootconf.txt pieeprom.bin
rpi-eeprom-update -d -f ./pieeprom-netboot.bin
shutdown -r now