September 2025 Maintenance Update for XCP-ng 8.3

New bugfixes, enhancement and non-urgent security updates are available for XCP-ng 8.3.

✅ Summary

This maintenance update for XCP-ng 8.3 includes routine updates to key components such as Xen and XAPI, with initial improvements over some network performance issues encountered with AMD EPYC.

✨ Improved networking performance for Linux guests on AMD hardware

After countless efforts from our developers to identify bottlenecks in VM to VM (and VM to same host) network performance on AMD hardware (EPYC, notably), we found a first fix which greatly improves the situation.

This is not the end of the way towards better performance on AMD EPYC servers, but it's significant progress, with network throughput more than doubled in some cases!

While we are confident with this change, we decided to make it opt-in at first, so that users be conscious of the change and also know how to revert it if any side effects remain in edge cases. To enable the fix pool-wide:

• Create a file named /etc/xenopsd.conf.d/custom.conf with the following line: xen-platform-pci-bar-uc=false
• Restart the toolstack on the host: xe-toolstack-restart
• Add the configuration and restart the toolstack on every other hosts of the pool
• Then stop and start VMs so that the setting is applied to them at boot.

In a future update, this will become the default.

OS support for the AMD performance fix

The change only affects Linux guests. To make it effective, their kernel must support the feature which enables this fix. Linux distributions that have recent enough kernels or apply fixes from the mainline LTS kernels support it. Older ones don't (example: Ubuntu 20.04). Some currently supported LTS distros don't have the required patch yet, notably RHEL 8 and 9 and their derivatives. This might change if we can convince them to apply the patch to their kernel.

🪲 Other bugfixes and improvements

• blktap: Fix a bad integer conversion that interrupts valid coalesce calls on large VDIs. This fixes an error that could occur on VHD coalesces, generating logs on the SMAPI side.
• broadcom-bnxt-en: Update driver to version 1.10.3_232.0.155.5
• kernel:
  • Fix compatibility issues with Minisforum MS-A2 machines. For more information, you can consult this forum thread.
  • Backport fix for CVE-2020-28374 , a vulnerability that is unlikely to be exploitable in XCP-ng, fixed as defence-in-depth.
• xsconsole: A bug was found in the Emergency Network Reset feature when triggered from xsconsole, due to desynchronisation between xsconsole and XAPI. This issue prevented the Emergency Network Reset from working at all. This update includes the fixes from the upstream xsconsole project to fix it.
  • Backport sync of network reset trigger file path with XAPI to fix emergency network reset
  • Fix IPv6 truncation when pre-filling the network reset dialog

🧰 Updates to other components

🔭 XO Lite

XO Lite is a lightweight, web-based interface built into XCP-ng that lets you manage your host and virtual machines directly from a browser—without needing to install Xen Orchestra (XO) separately. It will provide essential features like VM creation, control, and basic monitoring, making it ideal for quick tasks or minimal setups.

⚠️ XO Lite is not feature-complete yet. It is still in development.

We updated XO Lite to version 0.14.0. XO Lite changelogs are provided along with Xen Orchestra's latest release announcements.