It looks like a bug was probably introduced into 4.1, where stock Ubuntu 12.04 doesn't support part of the libvirt xml format for system vms. I feel bad that it got in there, but I think it highlights an issue that needs to be addressed within our development. Libvirt versioning is somewhat of a moving target. Features are introduced rapidly, and versions vary quite a bit between distributions and releases of those distributions. Despite this, we've largely ignored what libvirt we are targeting, assuming "whatever is on the distribution". There is the occasional discussion about this or that being available in libvirt x.x.x during the development cycle, but when it comes to qualifying the release we don't pay attention to it. We should. Looking at the vote for 4.1.0, several people call out which OS/distribution they use, but I'd like to see the libvirt version as well.
Here are some initial thoughts, please add to these if you can: 1) When voting for a release, should we require a minimum number of votes FOR EACH supported OS? Meaning that we require positive test results from every OS listed as supported? In retrospect this seems like a no-brainer, however it may change the bylaws. 2) Do we want to pull libvirt out as a standalone dependency? Meaning that we code to a specific version and make that more visible. This could be a "least common denominator" type thing where we pick the lowest version from all supported OSes, or it could be independent of distribution, whatever we decide, but we would make an effort to call out the version and treat it independently of OS. 3) I can think of a few things we could do in packaging to help catch versioning, but I'm not sure they would entirely address the issues.
