Comment 3 for bug 1391656

Matthew, that's almost 100% opposite of the point of diskimage-builder existing. We love modularity, and would love to have a patch that enabled customization of the boot loader installation arguments. Please clone https://git.openstack.org/openstack/diskimage-builder.git and then use this process to submit a patch:

http://docs.openstack.org/infra/manual/developers.html

You can ping us on IRC if you need realtime existence. We're on Freenode in #tripleo