T> Does the xen provider (libvirt/xen-cim) uses the xenstore to T> access/change the configuration information regarding the domains. T> e.g if Xen Client has to changes the memory allocation for any of T> the domain (i assume discover of domain/UUID/domid is already done) T> then can it uses xenstore to perform the operation in following T> way. We use libvirt to perform things like this, so your question is really one of "how does libvirt change the memory for a Xen guest". I believe that libvirt goes through xend to make such changes, but I could be wrong. There are three drivers in libvirt that provide different paths to make certain changes. Some things are done directly against the hypervisor, while others go to xend directly. By default, a combination of those drivers are used. From a quick look at the libvirt code, I think the virDomainSetMemory() call is being sent to xend. Hope that helps... -- Dan Smith IBM Linux Technology Center Open Hypervisor Team email: danms(a)us.ibm.com

T> basically i want to know that is xend manipulate the xenstore to T> change the VM's memory or there any other mechanism which dom0 T> follows. That is quite offtopic for this list. I suggest you go ask on xen-devel. T> If ballooning of memory happens through xend, it means two paths which T> i am not sure how it happens. T> 1. Xenstore shared memory page and event channel is mapped to dom0 T> memory area. Now xend enamurate all the VM's in xenstore thorough xen T> bus. Now change the balloon watch node for the concern domain, i.e T> /local/domain/domaid/memory/target <value> T> 2. Instead of using the xen bus interface, xend directly uses the T> xenstore API (i.e. xenstore-write) to manipulate the xenstore node. I don't really see how these are different, but yes, xend writes to the xenstore node to set the memory target. -- Dan Smith IBM Linux Technology Center Open Hypervisor Team email: danms(a)us.ibm.com