[libvirt] The problems of default settings

Hi all, I am recently considering about the default setting for different platforms. Currently, there is no good way to fix the default setting for PPC64 platform. For example, we prefer pseries on PPC64 as the default machine type users don't need to specify it. I am thinking about the solutions. 1. One solution I am thinking about is to create template xml files for different platforms. But if users give their own configuration XML files, how to keep the preferred configurations in domain definition. I think this solution should be better in management tools, for example, ovirt or openstack. After management tools can generate its own configuration files with different default settings, libvirt can help create according to XML files. 2. Another solution is to use hook in libvirt. But it seems that we need to use hook daemon. Is it complex to use? I am not familiar with hook. Any suggestion is appreciated. Thanks. :) --Li