[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] xenstore -- read UUID


  • To: Derek.Murray@xxxxxxxxxxxx
  • From: "Geoffrey Lefebvre" <geoffrey@xxxxxxxxx>
  • Date: Wed, 10 Sep 2008 08:31:11 -0700
  • Cc: xen developers community <xen-devel@xxxxxxxxxxxxxxxxxxx>, xen users community <xen-users@xxxxxxxxxxxxxxxxxxx>, dinesh chandrasekaran <dinesh_chan8@xxxxxxxxxxx>
  • Delivery-date: Wed, 10 Sep 2008 08:31:32 -0700
  • Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references:x-google-sender-auth; b=ugBULXexvNhAY/KJygAz1vYj3pax3qT/h2Lhyh3ILxDAOH8iBHMCY0p1TlG4/TtnU5 FXxYsNt+JQTICVUZDiB7H2Uav9KjTX122ZQ3uF+D7RMdi3l5IuWuiZHsDdmI/dJl6QG5 sYlahXgZ3STnkJXcaLi8bmlNyirmVH7Ya4h+c=
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

Hi everyone,

Sorry for the late joining to this thread.

If you really want to gather a domain's uuid from within the
hypervisor, it's actually possible to do without xenstore.
A domain's uuid gets stored as a xen_domain_handle_t in the domain
handle field (see xen/include/xen/sched.h and xen/commom/domctl.c).
The uuid of a domain gets passed to xen on domain creation. The uuid
can also be read from a privileged domain by issuing the
XEN_DOMCTL_getdomaininfo hypercall.

But as Derek mentioned earlier, you can read the domain uuid from a
guest via xenstore which is probably a better idea.

cheers,

geoffrey

On Wed, Sep 10, 2008 at 4:49 AM, Derek Murray <Derek.Murray@xxxxxxxxxxxx> wrote:
> Hi Dinesh,
>
> On Wed, Sep 10, 2008 at 1:24 AM, dinesh chandrasekaran
> <dinesh_chan8@xxxxxxxxxxx> wrote:
>> they were 2 seperate questions... sorry for the typos...
>> How to access xenstore from Dom-0? -- which you said 'YES'...
>
> Yes, this is certainly possible: your code should work (I haven't
> tested it) in Dom0 user-space. For another example, see
> tools/xenstore/xsls.c, which implements ls functionality for xenstore
> using the same interface.
>
>> And How to access xenstore from hypervosor?
>
> There is no code to do this in Xen at the moment.
>
>> If the hypervisor has no knowledge about XenStore, Dom-0 must have the full
>> control over the xenstore.
>
> Correct. XenStore is simply implemented as a user-space daemon
> (xenstored), running as root in Dom0.
>
>> I need to build a table with some fields one of which should never change
>> during a VMs lifetime.
>> For example, if I chose the domain_id whose value is transient, If the VM
>> reboots, its domain_id changes.
>> That is the reason why I opted for the UUID of a domain that persists over
>> time even after migration to another machine.
>> The only way I could get a domain's UUID is through the xenstore and want to
>> take away domain-0 from the picture, which
>> according to you is almost impossible.
>
> Instead of Dom0, you could possibly do this in a stubdomain. It is
> possible to access XenStore from a MiniOS-based domain.
>
> Regards,
>
> Derek Murray.
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
>

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel


 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.