@hrvojer I can't tell for sure without detailed troubleshooting, but your crash reminds me of a bug in XenVbd that was fixed in the XCP-ng 9.1.200 tools (Apr 2026). It's unlikely that updating to an old Xen tools version would help in that case.

@hrvojer There are many bugs in older versions of the Xen PV drivers. I suggest running Windows without guest tools and drivers if you can take the performance and functionality hit (no suspend/migration on UEFI VMs, no metric reporting, etc).

Hello, this issue has been fixed in XAPI 26.1.19-1.1 available in the testing updates. For now you have to configure your VMs manually (https://docs.xcp-ng.org/troubleshooting/common-problems/#pci-passthrough-error-unsupported-msi-delivery-mode-7) but the fix will be activated by default in the future.

@ovicz Which exact version of XAPI do you have? If you have 26.1.19-1.1 from testing, you should be able to fix it by setting hvm-pirq=false using the instructions here: https://docs.xcp-ng.org/troubleshooting/common-problems/#pci-passthrough-error-unsupported-msi-delivery-mode-7

@ovicz Have you set platform:hvm-pirq=false on it? The disable-by-default behavior had to be reverted in the upstream fix because of an unforeseen regression.

@flakpyro Note that various important Viridian settings are not yet settable via Xen Orchestra, so you might want to confirm using xe instead.

@flakpyro These template updates only concern new "from scratch" VMs. Older VMs should not be impacted at all.

But if some of your VMs are missing Viridian settings, you may run into poor performance and/or odd Windows issues. You can correct them using the instructions documented here: https://docs.xcp-ng.org/vms/#enabling-viridian-extensions

@ovicz I was wrong, it's already in testing. So you could simply install the testing updates for that.

@ovicz xcp-ng-ndinh2 currently contains a newer xapi 26.1.19 with some other patches you don't need, so you shouldn't use that any more.

The hvm-pirq feature have been integrated into our xapi 26.1.19 package, now available in testing. You can install the testing packages and get that feature. now available in incoming. But that's very early and not yet tested. If you need something based on the latest testing packages instead, feel free to ask me and I'll build it into a different tag for you.

Note that you should only upgrade XAPI packages listed in the RPM commands given above. Don't upgrade anything else or you may end up taking something unexpected.

@trelane Hello, the bug affects Xen drivers of any 9.0 series (considering the upstream code, it goes back to circa September 2019). 9.2.385 contains the fix, which was merged upstream just this month. The bug also impacts network connections, however to a lesser extent due to its nature.

I believe that the bug is also present in XenServer VM Tools 9.6.0 and by extension, older versions of it.

We recommend that you switch to the XCP-ng tools whenever possible, also due to its other benefits (fully open source, validated for XCP-ng and optimized for Xen Orchestra).

Hello,

Windows only supports adding CPUs but not removing them.

This is a Windows limitation.

@yomeyo Could you report a false positive for the detected file? Thanks.

Hello all,

Version 9.2.385 Release of the Windows guest tools has been released.

Download the latest release here: https://github.com/xcp-ng/win-pv-drivers/releases

This release brings important bug fixes to the Windows drivers, installer and XenClean.

Important note for users upgrading from 9.2.350: You must first install the included XenTools-fix-9.2.351.msp hotfix to upgrade to 9.2.351 before installing 9.2.385. Otherwise, upgrades from 9.2.350 will be blocked. Reboot is not required after installing the hotfix.

To download XenClean, click here. The installer downloads also includes a copy of XenClean and XenBootFix. It is not necessary to run XenClean when upgrading from previous versions of the XCP-ng Windows guest tools, unless prompted by the installer. Remember to carefully read XenClean docs before use.

Note: Always download the latest XenClean/XenBootFix from https://github.com/xcp-ng/win-pv-drivers/releases

Before installing

Thank you for using our Windows PV tools. Please carefully read the instructions below.

• It is not necessary to run XenClean when upgrading from previous versions of the XCP-ng Windows guest tools, unless prompted by the installer.
• Not compatible with the "Manage Citrix PV drivers via Windows Update" option. You must disable this option before installing.

Changes since 9.2.350

• Improved: Update XenClean to .NET 10. XenClean is now a native binary that no longer requires .NET Framework.
• Fixed: Fix data corruption issue during in-memory snapshots and backups.
• Fixed: Fix DLL sideloading issue in XenClean.
• Fixed: Fix driver migration during upgrades.
• Fixed: Fix display of IPv6 addresses in Xen Orchestra in some situations.
• Fixed: Reliability and stability fixes for the drivers and guest agent.

Help / Community support

If you encounter installation/uninstallation errors, please try again with one of the following commands:

For installing:
msiexec.exe /i XenTools-x64.msi /l*vx install.log

For uninstalling:
msiexec.exe /x XenTools-x64.msi /l*vx uninstall.log

Please include this log along with the file C:\Windows\INF\setupapi.dev.log in your bug report. These files will help us troubleshoot any installation issues.

Additionally, please report any errors or BSOD you encounter during testing of this release. Your feedback is very appreciated.

@ovicz I've built xapi-26.1.16-1.2.0.pirq.1.xcpng8.3 on xcp-ng-ndinh2. You can update as usual, then install my packages on top.

@ovicz xapi-26.1.16-1.1.0.pirq.2.xcpng8.3 is now available on xcp-ng-ndinh2, which disables HVM PIRQ for all existing VMs by default on reboot. Please try it out.

I've prepared an upstream PR for this feature. If you'd like to be listed as a tester, please respond with your name and email address (or your fake github email if you prefer) and I'll update my commit with your credit.

@archw Which AV is causing the warning, can you report it as a false positive?

@clip This often happens with Driver Verifier enabled, what do verifier /querysettings and verifier /query say?

@ovicz Thanks for testing. Is everything working without the pci=nomsi or GRUB command line tweaks? We'll work to integrate this fix into a future update.

@ovicz Are you up for a test package with a fix? Note that the fix is not yet tested nor supported at the moment.

Add user repos using this command:

yum-config-manager --add-repo https://koji.xcp-ng.org/repos/user/8/8.3/xcpng-users.repo

To know what you need to upgrade, run this command (as xcp-ng-ndinh2 contains some changes that you don't need):

rpm -qa --qf '%{NAME}\t%{SOURCERPM}\n' | grep $'\txapi'

Then upgrade just the XAPI-related packages:

yum update --enablerepo=xcp-ng-ndinh2 <list of packages from above>

Remember to reboot the host after installing.

Finally, disable hvm-pirq on your affected VM and reboot it (parameter name subject to change):

xe vm-param-set uuid=... platform:hvm-pirq=false

To go back, list what you installed and downgrade them:

yum list installed | grep ndinh
yum downgrade ...

@yomeyo It's a client shutdown being misreported as a client error. I'll fix this in the next release.

The warning on upgrade should be harmless and you can simply close the application/click OK as you've done.