Upgrade machine type during migration

[Michael Schwartzkopff]

Hi,


I have an old system. The guest there is defined with:

   <os>
     <type arch='x86_64' machine='pc-q35-rhel8.2.0'>hvm</type>
   </os>


When I try to migrate this guest to a new system I get the error:

error: internal error: unable to execute QEMU command 'blockdev-add': 
Failed to connect socket: Permission denied

On the new host I see the log entries:

libvirtd[22411]: Domain id=18 name='test02' 
uuid=9bad33a8-d18e-4c68-bdbe-dad34142dc22 is tainted: deprecated-config 
(machine type 'pc-q35-rhel8.2.0')
systemd-machined[9980]: New machine qemu-18-test02.
systemd[1]: Started Virtual Machine qemu-18-test02.
systemd-networkd[3914]: vnet20: Link DOWN
systemd-networkd[3914]: vnet20: Lost carrier
kernel: br1: port 3(vnet20) entered disabled state
kernel: device vnet20 left promiscuous mode
kernel: br1: port 3(vnet20) entered disabled state
systemd[1]: machine-qemu\x2d18\x2dtest02.scope: Deactivated successfully.
systemd-machined[9980]: Machine qemu-18-test02 terminated.
libvirtd[22411]: migration successfully aborted


It seems there is no possible combination of machine types that is 
compatible for both hosts. The old host only can start rhel8.2 guests, 
the new one only rhel9.0.


Is there a possibility to change the machine type during a migration? Is 
such a migration possible? Or do I have so shut down the guest?

Michael Schwartzkopff