Mixed CPU infrastructure issues

[T0schi]

Hello community,
since we upgraded our OpenStack environmet to Ussurri, we are facing more and more issues with our mixed CPU infrastructure ( Intel and AMD).
We are creating our Windows images with the imaging tools on a bare metal host with Intel CPU´s. The creation is running fine, the image import to OpenStack also. But when a new instance is spawned and is placed on an AMD host, the VM always runs into a Bluescreen

After a migration ( even to another AMD host) the VM is booting without any problems.

Now i am struggling where to start searching for the issue. I haven´t found huge changes on Nova in the Ussuri release notes.
Out settings
[libvirt]
inject_partition = -2
inject_password = False
inject_key = False
virt_type = kvm
cpu_mode = custom
cpu_model = Skylake-Server-IBRS
cpu_model_extra_flags = null

As the VM´s are running fine after the migration, i assume that only come CPU flags / Metadata missing, which are set during the migration.

Is there a way to have or include a "CPU pre check" in the created images or is it an issue only related to Nova which has to be addressed there?

[Adrian Vladu]

Hello,

I think setting this flag to false might work:
https://github.com/cloudbase/windows-openstack-imaging-tools/blob/master/Config.psm1#L130

[sysprep]
persist_drivers_install=false

Thank you,
Adrian Vladu

[T0schi]

Hi Adrian, thank you for the hint but changing this setting result in Bluescreens on every Boot on a AMD host, even after a migration (on Intel hosts everything is running fine). I´ve checked it with several Windows versions.
Any other idea?
If not, i think we have to test it with "cpu_mode = host-model" in nova.