Re: Networking test runs run-vmm twice with the same VM ID

[Alyssa Ross <hi@alyssa.is>]

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Demi Marie Obenour <demiobenour@gmail.com> writes:

> The networking test runs run-vmm twice with the same VM ID.
> If it waits for the previous cgroup to be empty, the second
> call waits forever.
>
> Is this expected?  I would expect that run-vmm is only called
> once.

Assuming you mean run twice in sequence, rather than run twice at the
same time, then yes, it is expected.

The way it works at the moment is that imported VMs have a VM ID
assigned when they're imported, and they can then be started any number
of times.  When the VM shuts down, the VMM exits, so if the VM is
started again after that, run-vmm will be run again with the same VM ID.
If this were not the case, VM IDs could not be assigned at import time,
and stay the same between successive boots of the same VM.

If your cgroup is not being emptied as expected, that is a bug,
regardless of whether it ends up being used again, because there
shouldn't be lingering processes or cgroups hanging around forever.
It sounds like we should have a test that confirms that this doesn't
happen, if it's hard to get right.

The networking test does do something slightly unusual, which is that it
restarts the VMM with s6-svc -Wr -r, rather than e.g. via the Cloud
Hypervisor API.  I would expect that this runs the finish script, but
might be worth confirming.

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