> > This... is theory. In practice, major architectural changes will break > things and need to be tested. For example, the anaconda environment > for RHEL 6 does not contain the "dirname" command. The environment for > RHEL 5 did. I anticipate that CentOS 6 will also lack it. Who would > know that without testing their kickstart scripts? And don't get me > started on the NetworkManager related changes in > /etc/sysconfig/network-scripts: the new "NM_CONTROLLED" option can > cause enormous confusion. I was referring to certified applications with regards to compatibility rather than kickstarting boxes and then you'll want to test out to see if you need any of the compatibility libaries.... With fresh package lists and so on of course you'll want to test out kickstarts... On any server I'd recommend disabling the networkmanager service and enabling the old network one... In fact on a server no point even installing the networkmanager packages... However that is pretty much OT from the original question and point of this thread which is that from 5.4 to 5.6 (and onwards) there will be no API/ABI breakages staying with the official channels. James