Re: [libvirt-users] how to change existing domain xml?

On 01/24/2012 10:15 AM, p-man314(a)mail.ru wrote: Correct, but not the full story. Question - is your guest running or inactive? Remember, there are two types of guests: persistent and transient; persistent guests can be offline (inactive) or running, while transient is always running. virDomainDefineXML() can only set the XML for an offline persistent guest (if called on a transient guest, the guest is converted over to persistent). As a result, when you use that API (such as via 'virsh edit'), you are only affecting the state of the guest for the next time it is booted, not the current running guest. The reason you can't do a whole-sale replacement of a running guest's XML is that the running XML must match the current state of the running guest. However, there are many API that allow you to change a portion of the running guest's XML; although 'virsh edit' cannot expose these API, there are many other virsh commands that can do this piece-wise editing. For example, virDomainSetMemoryFlags takes a flags argument; if flags is 0, then you affect the current state of the guest (that is, a hot-plug operation on any transient or running persistent guest, or the next boot of an inactive persistent guest); if flags is VIR_DOMAIN_AFFECT_LIVE, then you affect the running guest (and error out if the guest is inactive); if flags is VIR_DOMAIN_AFFECT_CONFIG, you affect the next boot only (and error out if the guest is transient); or you can pass both flags at once. This maps back to 'virsh setmem' which has --current, --live, and --config as flag options. -- Eric Blake eblake(a)redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org