I am running a PXE booted Raspberry cluster: one pi is the PXE boot server with has an SSD attached and is updated to 4.14.82-v7+ #1165. The boot-image for the PXE clients is rsync'ed. Clients boot up ok but do not update themselves to the latest release. uname -a returns: 4.14.34-v7+ #1110 despite even a firmware update to rpi-4.14.y.

I noticed that they are not updating when I tried to install the latest docker, which runs fine on the master (PXE boot server) but fails on the clients because /lib/module/4.14.34-v7+/* does not exist anymore. Somewhere the release update is out of sync with the PXE boot image? I think when I did an autoremove on the master the rsynced PXE poot image was also updated to remove the 4.14.34-v7+ version. Can that cause the apt-get process to think it already has the latest?


  • I did a: sudo apt-get update; sudo apt-get install --reinstall raspberrypi-bootloader raspberrypi-kernel .. as recommended in a similar out-of-sync post but uname still returns the same 4.14.34 version after a reboot. – tak Nov 27 at 3:53

It seems the out-of-sync situation between the PXE-boot client kernel version was caused by messing with the python versions and this causing apt-get to lose track of things. The /lib/module/4.14.34* files were gone on the PXE-boot image and I could not find an easy way to restore them.

My solution was to take one of the cluster-Pi's out and fit it with an SDcard with a fresh Raspbian install, go through the standard configuration and update, then reboot.

create a mount point

sudo mkdir /nfs

mount the PXE-boot server's location for pi's

sudo mount -t nfs {your PXE-boot server IP address}:/nfs-client1 /nfs

clean out the directory if you messed with it.

then rsync the current OS to the mounted location

sudo rsync -xa --progress --exclude /nfs / /nfs/client1

sudo umount {your PXE-boot server IP address}:/nfs-client1

you can shutdown the SDcard Pi and take the SDcard out for the next adventure and join it back to the cluster. It will be PXE-booted next.

back on the PXE-boot server:

Regenerate SSH host keys on the client filesystem by chrooting into it:

cd /nfs/client1

sudo mount --bind /dev dev

sudo mount --bind /sys sys

sudo mount --bind /proc proc

sudo chroot .

rm /etc/ssh/ssh_host_*

dpkg-reconfigure openssh-server


sudo umount dev

sudo umount sys

sudo umount proc

power-cycle all the PXE-client and they should boot up with the current version of the system.

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