[Xen-users] Re: [libvirt] domain.info() sometimes returns state zero for running machines

[Andreas Sommer <AndiDog@xxxxxx>]

Sorry but I misunderstood your last post completely :-D but now I tried 
what you said, using the CVS version. I also dumped the "ret" value from 
virXen_getdomaininfo. The output was simple: ret=1, domain_flags=0 
(right after XEN_GETDOMAININFO_FLAGS!!!). Sadly I don't have much time 
to dig deeper but it seems to me that this happens very seldom or 
sometimes not at all (hard to debug).

Daniel P. Berrange wrote:
> On Thu, Jun 18, 2009 at 09:40:08AM +0100, Andreas Sommer wrote:
>   
> > I executed the commands "export LIBVIRT_DEBUG=1" and "virsh dominfo 2" 
> > (ID 2 was a running domU), this is the output:
> > -----------------------------------------------------------------------------------------
> > DEBUG: libvirt.c: virInitialize (register drivers)
> > DEBUG: xen_internal.c: xenHypervisorInit (Using new hypervisor call: 30002
> > )
> > DEBUG: xen_internal.c: xenHypervisorInit (Using hypervisor call v2, sys 
> > ver6 dom ver5
> > )
> > DEBUG: libvirt.c: virConnectOpenAuth (name=(null), auth=0xb7f49b60, flags=0)
> > DEBUG: libvirt.c: do_open (Probed xen:///)
> > DEBUG: libvirt.c: do_open (Probed qemu:///system)
> > DEBUG: libvirt.c: do_open (Using xen:/// as default URI, 2 hypervisor found)
> > DEBUG: libvirt.c: do_open (name "xen:///" to URI components:
> >  scheme xen
> >  opaque (null)
> >  authority (null)
> >  server (null)
> >  user (null)
> >  port 0
> >  path /
> > )
> > DEBUG: libvirt.c: do_open (trying driver 0 (Test) ...)
> > DEBUG: libvirt.c: do_open (driver 0 Test returned DECLINED)
> > DEBUG: libvirt.c: do_open (trying driver 1 (Xen) ...)
> > DEBUG: xen_unified.c: xenUnifiedOpen (Trying hypervisor sub-driver)
> > DEBUG: xen_unified.c: xenUnifiedOpen (Activated hypervisor sub-driver)
> > DEBUG: xen_unified.c: xenUnifiedOpen (Trying XenD sub-driver)
> > DEBUG: xen_unified.c: xenUnifiedOpen (Activated XenD sub-driver)
> > DEBUG: xen_unified.c: xenUnifiedOpen (Trying XS sub-driver)
> > DEBUG: xen_unified.c: xenUnifiedOpen (Activated XS sub-driver)
> > DEBUG: libvirt.c: do_open (driver 1 Xen returned SUCCESS)
> > DEBUG: libvirt.c: do_open (network driver 0 Test returned DECLINED)
> > DEBUG: libvirt.c: do_open (network driver 1 QEMU returned DECLINED)
> > DEBUG: remote_internal.c: doRemoteOpen (proceeding with name = xen:///)
> > DEBUG: libvirt.c: do_open (network driver 2 remote returned SUCCESS)
> > DEBUG: libvirt.c: do_open (storage driver 0 Test returned DECLINED)
> > DEBUG: libvirt.c: do_open (storage driver 1 storage returned DECLINED)
> > DEBUG: libvirt.c: do_open (storage driver 2 remote returned SUCCESS)
> > DEBUG: libvirt.c: virDomainLookupByID (conn=0x9b49048, id=2)
> > DEBUG: hash.c: __virGetDomain (New hash entry 0x9b580a0)
> > DEBUG: libvirt.c: virDomainGetID (domain=0x9b580a0)
> > DEBUG: libvirt.c: virDomainGetName (domain=0x9b580a0)
> > DEBUG: libvirt.c: virDomainGetUUIDString (domain=0x9b580a0, buf=0xbff74b07)
> > DEBUG: libvirt.c: virDomainGetUUID (domain=0x9b580a0, uuid=0xbff74aac)
> > DEBUG: libvirt.c: virDomainGetOSType (domain=0x9b580a0)
> > DEBUG: libvirt.c: virDomainGetInfo (domain=0x9b580a0, info=0xbff74b2c)
> > DEBUG: libvirt.c: virDomainGetAutostart (domain=0x9b580a0, 
> > autostart=0xbff74b44)
> > DEBUG: libvirt.c: virDomainFree (domain=0x9b580a0)
> > DEBUG: hash.c: virUnrefDomain (unref domain 0x9b580a0 
> > ac06e4f0-59b1-11de-8a39-0800200c9a66 1)
> > DEBUG: hash.c: virReleaseDomain (release domain 0x9b580a0 
> > ac06e4f0-59b1-11de-8a39-0800200c9a66)
> > DEBUG: hash.c: virReleaseDomain (unref connection 0x9b49048 xen:/// 2)
> > DEBUG: libvirt.c: virConnectClose (conn=0x9b49048)
> > DEBUG: hash.c: virUnrefConnect (unref connection 0x9b49048 xen:/// 1)
> > DEBUG: hash.c: virReleaseConnect (release connection 0x9b49048 xen:///)
> > -----------------------------------------------------------------------------------------
> >
> > This is pretty weird because there are no debugging messages from Xen 
> > functions?!
> >     
> Did you make the code changes I suggested below to add in the DEBUG()
> statements ? If so, then probably virsh is still using the system
> installed libvirto.so rather than the new built one. If you run virsh
> directly from the compiled source tree it'd probably work, eg ./src/virsh ...
>
>   
> > Daniel P. Berrange wrote:
> >     
> > > 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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