On Sun, Oct 29, 2017 at 08:39:08PM -0600, Jim Fehlig wrote:
Hi All,
It may be a foolish en devour, but I'm trying to make a qemu hook script that provides the semantics of an old, custom xen block script. The script parses <disk> info, does some setup based on that, and then rewrites part of the config based on results of the setup. As an example, here is an XML snippet of a <disk> device on input to the hook script
<disk type='block' device='disk'> <driver name='qemu' type='raw'/> <source dev='some-dev-config'/> <target dev='vdb' bus='virtio'/> </disk>
and XML returned by the script
<disk type='block' device='disk'> <driver name='qemu' type='raw'/> <source dev='/dev/foo'/> <target dev='vdb' bus='virtio'/> </disk>
The hook script performs the setup and substitution in the "prepare" phase, but I noticed the results are never used when subsequently starting the domain. Indeed qemuProcessStartHook passes a NULL buffer to virHookCall, so the output XML of the hook is never collected. Does anyone have objections to using the XML returned from the "prepare" and "release" hook script phases, similar to how it is used in the "restore" and "migrate" phases?
That was an explicit decision - we don't want hook scripts arbitrarily modifying the XML during startup. They're there to let you trigger external actions, but they're not there to let you modify the config. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|