Cloud Hypervisor v37.0 Released!

Posted December 14, 2023 by Cloud Hypervisor Team ‐ 2 min read

This release has been tracked in our roadmap project as iteration v37.0. The following user visible changes have been made:

Long Term Support (LTS) Release

This release is a LTS release. Point releases for bug fixes will be made for the next 18 months; live migration and live upgrade will be supported between the point releases of the LTS.

Multiple PCI segments Support for 32-bit VFIO Devices

Now VFIO devices with 32-bit memory BARs can be attached to non-zero PCI segments on the guest, allowing users to have more 32-bit devices and assign such devices to appropriate NUMA nodes for better performance.

Configurable Named TAP Devices

Named TAP devices now accepts IP configuration from users, such as IP and MAC address, as long as the named TAP device is created by Cloud Hypervisor (e.g. not existing TAP devices).

TTY Output from Both Serial Device and Virtio Console

Now legacy serial device and virtio console can be set as TTY mode as the same time. This allows users to capture early boot logs with the legacy serial device without losing performance benefits of using virtio-console, when appropriate kernel configuration is used (such as using kernel command-line console=hvc0 earlyprintk=ttyS0 on x86).

Faster VM Restoration from Snapshots

The speed of VM restoration from snapshots is improved with a better implementation of deserializing JSON files.

Notable Bug Fixes

  • Fix aio backend behavior for block devices when writeback cache disabled (#5930)
  • Fix PvPanic device PCI BAR alignment (#5956)
  • Bug fix to OpenAPI specification file (#5967)
  • Error out early for live migration when TDX is enabled (#6025)


Many thanks to everyone who has contributed to our release:


See the GitHub Release for the release assets.