Re: [libvirt] domain.info() sometimes returns state zero for running machines
On Wed, Jun 17, 2009 at 04:04:20PM +0100, Andreas Sommer wrote:
I'm using Xen-3.2-1 on Debian 5.0.1-lenny and retrieve
information about
running domains using
domain.info()[0]
The domain object is retrieved via connection.lookupByUUIDString(...)
and stored as a variable called "domain". Usually the running domains
have the state 1 (VIR_DOMAIN_RUNNING) or 2 (VIR_DOMAIN_BLOCKED), but
sometimes it happens that 0 (VIR_DOMAIN_NOSTATE) is returned.
Why does that happen? I don't think it is an error because then it
would've raised an exception...
I think it is most likely a bug in our handling of the state info
from the hypervisor with certain Xen version. I'm fairly sure we
should never get NO_STATE for any active domain
If you want to try and troubleshoot the code, then this handled in the
xenHypervisorGetDomInfo() method in src/xen_internal.c.
It currently does this:
domain_flags = XEN_GETDOMAININFO_FLAGS(dominfo);
domain_flags &= ~DOMFLAGS_HVM; /* Mask out HVM flags */
domain_state = domain_flags & 0xFF; /* Mask out high bits */
switch (domain_state) {
....
}
.
Given that you see NO_STATE, I expect that none of the 'case' inside
the 'switch' are being matched. I'd be interested to know what the
'domain_state' value is immediately after its fetched from the HV.
So you might try changing it to
domain_flags = XEN_GETDOMAININFO_FLAGS(dominfo);
DEBUG("Raw HV state flag %x", domain_flags);
domain_flags &= ~DOMFLAGS_HVM; /* Mask out HVM flags */
domain_state = domain_flags & 0xFF; /* Mask out high bits */
DEBUG("Masked HV state flag %x", domain_flags);
switch (domain_state) {
....
}
DEBUG("libvirt state flag %x", info->state);
And then running 'LIBVIRT_DEBUG=1 virsh dominfo GUEST' and
capturing the output when it reports 'nostate'
Daniel
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