[2.5] KVM pod deployment does not support ppc64

Bug #1797484 reported by Mike Pontillo on 2018-10-11
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Mike Pontillo

Bug Description

KVM pod deployment needs to be tested on a PPC64 host.

It is our current understanding that in order for libvirt to be used with KVM on PPC64, the following command needs to be run (as root) on the hypervisor before libvirt is usable:

    ppc64_cpu --smt=off

More details can be found here:


See also: bug #1794560 (for the AMD64 architecture)

Related branches

description: updated
summary: - [2.5] KVM pod deployment needs validation on ppc64
+ [2.5] KVM pod deployment does not support ppc64
Mike Pontillo (mpontillo) wrote :

I'm not sure how to work around this cleanly when deploying a KVM pod.

We can add an /etc/rc.local similar to the following:

    ppc64_cpu --smt=off
    exit 0

... which I prototyped, but I'm not sure about. It really seems like a hack. For example, is there a chance that libvirtd could start up before this gets executed? If so, what would be the effects of that race condition? (Is there another solution, such as a kernel parameter or sysctl, that would be better?)

Given that SMT refers to multithreaded CPU cores, would passing `smt=1` as a kernel parameter be more efficient at accomplishing this? (According to what I found in kernel-parameters.txt in the Linux documentation, smt=1 and nosmt are equivalent, but nosmt=force might be even safer.)

We should test this on actual hardware to confirm any proposed solution before moving forward with this.

Changed in maas:
assignee: nobody → Mike Pontillo (mpontillo)
status: Triaged → In Progress
Changed in maas:
status: In Progress → Fix Committed
Changed in maas:
milestone: 2.5.0rc1 → 2.5.0beta4
status: Fix Committed → Fix Released
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