Generally when someone wants to install a Linux distro they start with an ISO file. Now we could burn that to a DVD, walk into the server room, and put it in our machine, but that's a pain. Instead let's look at how to do this over the network with Petitboot!

At the moment Petitboot won't be able to handle an ISO file unless it's mounted in an expected place (eg. as a mounted DVD), so we need to unpack it somewhere. Choose somewhere to host the result and unpack the ISO via whatever method you prefer. (For example bsdtar -xf /path/to/image.iso).

You'll get a bunch of files but for our purposes we only care about a few; the kernel, the initrd, and the bootloader configuration file. Using the Ubuntu 16.04 ppc64el ISO as an example, these are:

./install/vmlinux
./install/initrd.gz.
./boot/grub/grub.cfg

In grub.cfg we can see that the boot arguments are actually quite simple:

set timeout=-1

menuentry "Install" {
    linux   /install/vmlinux tasks=standard pkgsel/language-pack-patterns= pkgsel/install-language-support=false --- quiet
    initrd  /install/initrd.gz
}

menuentry "Rescue mode" {
    linux   /install/vmlinux rescue/enable=true --- quiet
    initrd  /install/initrd.gz
}

So all we need to do is create a PXE config file that points Petitboot towards the correct files.

We're going to create a PXE config file which you could serve from your DHCP server, but that does not mean we need to use PXE - if you just want a quick install you only need make these files accessible to Petitboot, and then we can use the 'Retrieve config from URL' option to download the files.

Create a petitboot.conf file somewhere accessible that contains (for Ubuntu):

label Install Ubuntu 16.04 Xenial Xerus
    kernel http://myaccesibleserver/path/to/vmlinux
    initrd http://myaccesibleserver/path/to/initrd.gz
    append tasks=standard pkgsel/language-pack-patterns= pkgsel/install-language-support=false --- quiet

Then in Petitboot, select 'Retrieve config from URL' and enter http://myaccesibleserver/path/to/petitboot.conf. In the main menu your new option should appear - select it and away you go!