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Re: [Libvir] PATCH: Specify BIOS clock offset for HVM

On Fri, Jul 13, 2007 at 05:07:03PM +0100, Daniel P. Berrange wrote:
> The attached patch introduces a new XML element for specifying information
> about the guest (BIOS) clock. For Xen HVM, and QEMU / KVM guests this is
> used to specifyc whether the guest clock should be in UTC, or localtime.
> The latter is useful for Windows which likes the BIOS to be localtime,
> while the former is useful for all other operating systems. The former is
> of course the default - so no change in existing semantics.
> The <clock> element currently takes a single attribute 'offset'. This is
> either 'utc' or 'localtime', but if we port to VMWare, it will also allow
> an arbitrary numeric offset as well as these special constants.
>    <clock offset='utc'/>
> Or
>    <clock offset='localtime'/>
> It may later also be desirable to add a 'sync=[yes|no]'  attribute to 
> specify whether the HV tries to keep the clock in sync with the HV while
> it is running. VMWare has this concept, and so does Xen paravirt - though
> Xen paravirt sets it via /proc/sys/xen/independant_wallclock inside the
> guest and AFAICT doesn't (yet) expose it to the guest config in Dom0.
> Anyway, my patch implements use of utc/localtime offsets for Xen, and QEMU
> drivers. I've tested to verify that -localtime gets passed to the QEMU
> process as appropriate.

  Looks fine, the patch also includes a few cleanups. And this should
fix the clock annoyance when running Windows. I assume this will be
automatically added when installing a new Windows guest with virt-manager.

  Cool, +1 


Red Hat Virtualization group http://redhat.com/virtualization/
Daniel Veillard      | virtualization library  http://libvirt.org/
veillard redhat com  | libxml GNOME XML XSLT toolkit  http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine  http://rpmfind.net/

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