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

>>> 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. Yeah, I thought that was a longshot. Synchronization of the front and backend drivers doesn't necessarily mean the OS is in a position to respond to the shutdown event. Lacking a guest agent, another option would be to wait for the guests network stack to come alive, e.g. responds to pings or connection requests.

Regards, Jim