Cloud Hypervisor v21.0 Released!

Posted January 20, 2022 by Cloud Hypervisor Team ‐ 2 min read

This release has been tracked through the v21.0 project.

Efficient Local Live Migration (for Live Upgrade)

In order to support fast live upgrade of the VMM an optimised path has been added in which the memory for the VM is not compared from source to destination. This is activated by passing --local to the ch-remote send-migration command. This means that the live upgrade can complete in the order of 50ms vs 3s. (#3566)

Due to an issue in the virtio-net code in 5.14 the recommended Linux kernel is now 5.15. (#3530)

Notable Bug fixes

  • Multiple fixes were made to the OpenAPI YAML file to match the implementaion (#3555,#3562)
  • Avoid live migration deadlock when triggered during the kernel boot (#3585)
  • Support live migration within firmware (#3586)
  • Validate the virtio-net desciptor chain (#3548)
  • direct=on (O_DIRECT) can now be used with a guest that makes unaligned accesses (e.g. firmware) (#3587)


Many thanks to everyone who has contributed to our release:


See the GitHub Release for the release assets.