Change type of machine in KVM hypervisor

[SviridoffA]

Hi Everyone! Please help me 🙏! Can someone tell me if there's any way to change parameter arch='x86_64' machine='pc-i440fx-8.2' in a virtual machine's XML to arch='x86_64' machine='pc-q35-8.2' without CloudStack overwriting these changes, perhaps through some extra config set with the API (cmk)?

I am using:

ACS 4.19.3

Ubuntu 24.04

QEMU 8.2.2

[weizhouapache]

@SviridoffA
there is a recent PR for it: #11569

[SviridoffA]

Hi @weizhouapache, thanks for this information. It's a great enhancement, but if I can't build CloudStack myself with this PR, is there any other way to do this at the moment?

I have tried

cmk update virtualmachine id=<id> extraconfig="<os><type arch='x86_64' machine='pc-q35-8.2'>hvm</type></os>"

but looks like it's not correct. There are many another parameters related in XML.

[SviridoffA]

It seems the only way to do this now is to create a virtual machine with UEFI settings. If you choose this option, VM type will be set to pc-q35-8.2. However, this cannot be applied to an already existing virtual machine, as it may cause issues with the bootloader.

[SviridoffA]

Hi @DaanHoogland! Do you mean "virsh edit"? But won't it be overwritten during start or migration operations?

[DaanHoogland]

yes it will be a workaround, just to verify that it can run. While you wait for the more permanent solution mentioned above (#11583 (comment)).

[SviridoffA]

It seems like I'm missing something... But to apply these changes, I need to stop and start the VM, and if I stop and start it, the XML will be overwritten, right? So I can't apply these changes anyway)))

[DaanHoogland]

if you start from cloudstack, these changes will be overwritten, but if you stop/start out of bound they won’t.

[SviridoffA]

Thank you for your hint, I performed it using virsh shutdown and virsh start.
There are too many interconnected parameters in the XML that need to be adjusted for this type of virtual machine. I tried extracting config from the UEFI configuration and aligning it with the standard one. In the end, I managed to start the virtual machine, but I encountered an error with boot device. For now, I've given up and will wait for release.

[NuxRo]

Only manual way @SviridoffA

1. go to hypervisor
2. virsh edit instance-name, change to pc-i440fx-8.0 or whatever you need
3. virsh destroy instance-name (or "shutdown" if machine is responsive)
4. virsh start instance-name

[SviridoffA]

Hi @NuxRo! Thanks for you reply. As I wrote above, I followed the order you specified, but when we change the type from pc-i440fx to pc-q35, we also need to modify several parameters related to USB and PCI buses. When we change one thing, virsh requires changes to other parameters. I took all the necessary parameters from a virtual machine with UEFI, inserted them into config of the virtual machine whose type I’m changing, and removed UEFI-related section, after this virsh allowed me to save xml file. However, after starting the virtual machine, the system couldn’t identify boot device. ((