According to Canonical’s policy, a package version does not change on a Ubuntu LTS release.
This might impact some new features, that sometimes is required by the user. For example, you might need a newer libvirt or qemu that is not available in LTS archive.
In this case, there is a PPA for Ubuntu that provides newer packages for the LTS release. So, if you want to install QEMU 2.5 and libvirt 1.3 on Trusty, you can do that enabling the cloud archive PPA.
The cloud archive is released with the Openstack releases, so, for each Openstack release, a new set of packages is made available.
At Mitaka level, these are the version of the packages:
- Qemu: 2.5
- Libvirt: 1.3.1
- libseccomp: 2.2.3
- liblua: 5.3
- cepth: 10.2