Because not all features implemented in Open Virtuozzo are merged into vanilla kernel yet, it's been adopted to create a fork of CRIU with Virtuozzo specific patched on top of vanilla instance. The CRIU-VZ is open project of course with the following branches:
- master — is a copy of vanilla master branch
- vz7-rtm — Virtuozzo 7 criu instance
- vz7-u1 — current stable branch of Virtuozzo 7 with patches which will come into next Virtuozzo update
While vanilla CRIU is a fast pacing project the Virtuozzo instance is usually slightly behind. In particular currently v2.5 is used as a stable base.