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 the 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
The vanilla CRIU is a fast pacing project so for the Virtuozzo instance we take a version behind as a base (currently it is v2.5). We sacrifice functionality for stability reason - all the problems found during intensive testing are fixed in the Virtuozzo instance first, while merging them upstream may take up to months.