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ltsp kernel - copy the kernel and initrd from an image to TFTP


ltsp [ltsp-options] kernel [-k kernel-initrd] [image] ...


Copy vmlinuz and initrd.img from an image or chroot to TFTP. If image is unspecified, process all of them. For simplicity, only chroot directories and raw images are supported, either full filesystems (squashfs, ext4) or full disks (flat VMs). They may be sparse to preserve space. Don't use a separate /boot nor LVM in disk images. The targets will always be named vmlinuz and initrd.img to simplify ltsp.ipxe.


See the ltsp(8) man page for ltsp-options.

-k, --kernel-initrd=glob-regex
Specify a kernel glob and an initrd regex to locate them inside the image; try to autodetect if undefined. See the EXAMPLES section below.


This section is for advanced LTSP sysadmins. Let's suppose that you want to test if your users would prefer Xubuntu to your existing Ubuntu MATE. First, move and rename your Xubuntu CD to this location, without using symlinks, and then update kernels and ipxe:

mv xubuntu-18.04-desktop-amd64.iso /srv/ltsp/images/xubuntu-18.04.img
ltsp kernel xubuntu-18.04
ltsp ipxe

If you reboot your clients, they'll now have the option to boot with the Xubuntu live CD in LTSP mode! This is like booting with the live CD, except that all the users and their homes are available! So the users can normally login and work for days or weeks in the new environment, before you decide that they like Xubuntu and that you want to move from using the live CD to maintaining a Xubuntu image using a virtual machine.

You can also do this with virtual machine images! For example:

mv ~/VirtualBox\ VMs/debian/debian-flat.vmdk /srv/ltsp/images/debian-vm.img
ln -rs /srv/ltsp/images/debian-vm.img ~/VirtualBox\ VMs/debian/debian-flat.vmdk
ltsp kernel debian-vm
ltsp ipxe

These commands move your "debian" VM to the LTSP images directory, symlink it back to where VirtualBox expects it, and update the kernels and ipxe. After these, you'll be able to boot directly from the "debian-vm" iPXE menu item without having to run ltsp image! It's the fastest way to test image changes without waiting 10 minutes for ltsp image each time.

Some advanced users may think of using the opposite symlink instead:

ln -rs ~/VirtualBox\ VMs/debian/debian-flat.vmdk /srv/ltsp/images/debian-vm.img

Unfortunately NFS doesn't follow symlinks outside of the exported directories, so the clients wouldn't be able to boot in this case. Advanced users may use bind mounts though, e.g.:

mount --bind ~/VirtualBox\ VMs/debian/debian-flat.vmdk /srv/ltsp/images/debian-vm.img


Typical use:

ltsp kernel x86_64

Passing a glob to locate the kernel and a regex to locate the initrd in a Debian live CD:

ltsp kernel --kernel-initrd="live/vmlinuz-* s|vmlinuz|initrd.img|"