In the file installing/installing_with_agent_based_installer/preparing-to-install-with-agent-based-installer.adoc we should include a section about how to boot the Agent ISO from a USB disk.

The agent ISO produced by openshift-install agent create image is a bootable ISO9660 image (i.e. it contains boot information using the El Torito extension to ISO9660), so it can be booted from a (virtual) CD-ROM device.

However, it does not contain a Master Boot Record, so if you copy it to a regular disk with dd, it cannot boot. Live CD operating systems (including, on x86-64, the vanilla CoreOS Live ISO) typically contain both El Torito and MBR boot information so that they can be written to either a CD or a USB disk.

On RHEL, an MBR can be added to a bootable ISO with the isohybrid command:

isohybrid --uefi agent.x86_64.iso