[Libvirt-cim] Xen Domain Management CIM-Provider

[Tej]

On Wed, Jul 23, 2008 at 8:56 PM, Dan Smith <danms at us.ibm.com> wrote:
> 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".

yaa

>
> 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.

basically i want to know that is xend manipulate the xenstore to
change the VM's memory or there any other mechanism which dom0
follows.

If ballooning of memory happens through xend, it means two paths which
i am not sure how it happens.

1. Xenstore shared memory page and event channel is mapped to dom0
memory area. Now xend enamurate all the VM's in xenstore thorough xen
bus. Now change the balloon watch node for the concern domain, i.e
/local/domain/domaid/memory/target <value>

2. Instead of using the xen bus interface, xend directly uses the
xenstore API (i.e. xenstore-write) to manipulate the xenstore node.

my best guess is the path 1.

sorry for my little understanding on xend code.


>
> Hope that helps...
thanks for your quick reply.
-tej
>
> --
> Dan Smith
> IBM Linux Technology Center
> Open Hypervisor Team
> email: danms at us.ibm.com
>
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