Bug 1054935

Summary: cpu host-model should permanently encode the CPU definition on first define
Product: [Community] Virtualization Tools Reporter: Cole Robinson <crobinso>
Component: libvirtAssignee: Libvirt Maintainers <libvirt-maint>
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Last Closed: 2018-10-09 14:54:49 UTC Type: Bug
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Description Cole Robinson 2014-01-17 19:02:52 UTC
I'm thinking of what it will take to make host-model the default cpu mode for VMs in virt-manager. Right now there are still other issues with host-model, like it incorrectly modeling the host CPU, but this is another piece that I think is missing.

The host-model values are filled in every time the VM is run. This could potentially cause a problem on libvirt upgrade, if libvirt changed the logic for generating host-model, or a new CPU feature was added, or similar: the CPU definition would change across reboots, which could cause windows reactivation.

Possible solution is to do the host-model lookup only on the first VM run, and keep it forever. But not sure how that would work exactly.

Maybe this isn't an issue in practice or there's a better alternative...

Comment 1 Cole Robinson 2016-04-10 17:35:15 UTC
Still an issue with latest code

Comment 2 Cole Robinson 2018-10-09 14:54:49 UTC
This hasn't really turned out to be an issue any cares about in practice, so i don't think it needs explicit libvirt support. If apps care, they can grab the host-model CPU block from domcapabilities and define it into the XML themselves, which will accomplish the same goal