[libvirt] [PATCHv2 0/3] Xen: Fix <clock> handling

Philipp Hahn hahn at univention.de
Tue Feb 14 17:24:35 UTC 2012

Hello Eric,

On Monday 13 February 2012 18:43:21 Eric Blake wrote:
> > 2. Instead of implementing a second variant of offset='variable' it would
> > be enough to just add an attribute reset='true' (or
> > this_is_not_from_a_buggy_libvirt_and_I_really_need_the_reset='true') to
> > dumpxml, when a driver really implements the reset semantics. As long as
> > it's missing, libvirt can convert it to reset='false' in the Xen≥3.1
> > case. With an explicit reset='true' libvirt would return an error for
> > Xen-HV≥3.1.
> Once we add a new attribute, we can document that domain XML that omits
> the attribute will default to hypervisor-specific choices (xen < 3.1 can
> default one way, xen >= 3.1 can default another way, and qemu can
> default in a particular way as well).  If the user provides the
> attribute, then they are requesting the specific behavior that they need.

v3 implements this as following:
 adjustment='reset' forced the old behaviour with xen; xen-3.1 will reject 
those HV-domains.
 adjustment='$timeDelta' gets directly converted to offset='variable'.

> No.  We _don't_ want a libvirt version attribute.  What we want is a new
> attribute that, if present, determines the behavior according to the
> user, and if absent, provides sane upgrade semantics when parsing older
> XML into newer libvirt.

Okay. Thank you for your explanation; makes sense.

> You still haven't managed to convince me that we cannot solve this by
> adding new attributes.

I still find it a little bit strange to add an attribute to force the parser 
to the old behaviour of utc/localtime, which was perfectly clear. But if it 
improves compatibility, I'm fine with this solution.

Thank you for your feedback so far.

Philipp Hahn           Open Source Software Engineer      hahn at univention.de
Univention GmbH        Linux for Your Business        fon: +49 421 22 232- 0
Mary-Somerville-Str.1  D-28359 Bremen                 fax: +49 421 22 232-99
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 197 bytes
Desc: This is a digitally signed message part.
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20120214/ca8d5587/attachment-0001.sig>

More information about the libvir-list mailing list