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



On Mon, Jul 16, 2007 at 03:50:07AM -0400, Daniel Veillard wrote:
> 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.

Yeah, ignore the unrelated cleanups - I didn't mean to include them - i'll
commit them separately. Also ignore the stupid printf() debugging!

We're gonna hook it up in virt-install and virt-manager so that if you 
select a 'Windows' OS type, then it'll automagically configure the clock
to be in localtime.

Dan.
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