[libvirt] 答复: [libxl] shutdown a domain before it finishes starting

[Zhangbo (Oscar)]

>> Hi all:
>>     Suppose we have a guest domain which is pvops, for example, rhel6.4.
>>
>>     Steps to produce the problem:
>>     1 start the guest by virDomainCreate()
>>     2 the API returns before the guest domain fully available, which means,
>the disks, network interfaces and some import services are not available inside
>the guest.
>>     3 we call virDomainShutdown() to shutdown the guest.
>>
>>     Expected result:
>>       The guest got shutdown.
>>
>>     The result in fact:
>>       Because the guest is not available when we call virDomainShutdown(),
>it couldn't  respond to our 'shutdown' xenstore request, the guest turns on
>later, rather than shutting down.
>
>I don't think this is unique to a pvops guest kernel, or even a xen stack. I see
>the same behavior with qemu. 'virsh create dom.xml && virsh shutdown dom'
>results in the guest kernel missing the shutdown event and booting anyhow. I
>guess SeaBIOS could still be loading when the shutdown event is issued :-). The
>virDomainShutdownFlags documentation even states "that the guest OS may
>ignore
>the request". In my example, the guest OS isn't even alive yet.
>
>>     So , the question is:
>>        In libxl_driver( xen-hypervisor environment), how can we tell that the
>guest is available or not, and is it suitable to shutdown the guest at that
>moment?
>
>libxl has no API to determine if a guest OS has booted. In a qemu/kvm stack, I
>suppose qemu-ga is the preferred way to know when a guest OS has booted, or
>is
>far enough along to respond to shutdown events.
>
>One possible approach in xen, which is not supported by libvirt, would be to
>monitor the state of a device frontend in xenstore. E.g. when
>/local/domain/<domid>/device/vif/<vifid>/state reaches 4 (connected), you'll at
>least know the driver in the guest is up and running.

I've tried that way, but even the device state is not trustable, because inside the guest, it calls "add_disk" after the device state changes to 4, and  before it could respond the 'shutdown' xenstore request, which takes a while to complete.


>
>Regards,
>Jim