I haven't set up network boot for a Pi. How does cmdline.txt reach the Pi?Trying to get network boot to work, I'm using a 3B, I have an SD card in the RPi formatted as FAT32 with bootcode.bin on it.
I installed a fresh image of bookworm on a SD card, confirmed the RPi was running fine. I then shutdown the RPi and copied the two filesystems onto my NFS server, using two directories, a root and a boot directory, no other changes were made.
I used cpio to copy the filesystem
( ex - find . -depth -print| cpio -pdm /home/pi_nfsroot/1761fb86)
My dhcp-server (Opnsense) is configured to provide the IP address of the TFTP server via option 66
My cmdline.txt:looking at a network dump the RP obtains an IP address and then downloads from the tftpserver the following files -Code:
console=tty0,115200 console=tty1 root=/dev/nfs rootfstype=nfs nfsroot=172.18.19.2:/home/pi_nfsroot/1761fb86,vers=3 rw ip=dhcp rootwait elevator=deadline
1761fb86/config.txt
1761fb86/start.elf
1761fb86/fixup.dat
1761fb86/initramfs8
after downloading the initramfs8 it just stops and the interface of the RPi doesn't respond to a ping or arp request.
It appears as if I'm not even getting to the NFS mounting of filesystems (which I know are working) as I don't even see the RPi request the cmdline.txt file.
I'm sure I'm missing something simple.
Around here some PCs network boot using iPXE and subsequently load the kernel and initial RAM filesystem through http. There are also PCs that use PXE to load grub through TFTP. In that case nfsroot is obtained from the DHCP server using the root-path option.
The card-less Pi computers here are Pi 4 and Zero models which load the operating system over the USB C port in device mode. The sequence of files in that case are
Code:
Waiting for BCM2835/6/7/2711...Sending bootcode.binSuccessful read 4 bytes Waiting for BCM2835/6/7/2711...Second stage boot serverFile read: config.txtFile read: start_cd.elfFile read: fixup_cd.datFile read: config.txtFile read: config.txtFile read: myinitrd.imgFile read: bcm2708-rpi-zero.dtbFile read: overlays/overlay_map.dtbFile read: config.txtFile read: overlays/dwc2.dtboFile read: cmdline.txtFile read: mykernel.imgSecond stage boot server doneIs it possible some symbolic links got mixed up or don't work on your tftp server?
Sorry, I can't offer more help. I am interested in reading what other people reply.
Statistics: Posted by ejolson — Sat Nov 08, 2025 6:11 am