[RFC REPOST 0/7] introduce support for live appid updates

[Daniel P. Berrangé]

On Fri, Sep 10, 2021 at 03:26:20PM +0200, Pavel Hrdina wrote:
> On Fri, Sep 10, 2021 at 12:57:30PM +0100, Daniel P. Berrangé wrote:
> > On Thu, Sep 09, 2021 at 06:13:16PM +0200, Pavel Hrdina wrote:
> > > Rebased on top of current master.
> > > 
> > > I'm posting this as an RFC mainly because I'm not sure how to model
> > > the new API. This patches introduce a new naive API that will change
> > > only the APPID and nothing else.
> > > 
> > > Currently there are no other known features related to Fibre Channel
> > > resources so this non-extendable API will be sufficient, however the
> > > appid lives in <resource> element in the XML where we currently have
> > > root cgroup partition. Even though changing the partition will not be
> > > supported and we don't know about anything else that could be placed
> > > here it doesn't mean it will not happen in the future. In that case
> > > we would have to add new API as well.
> > 
> > I'm curious why we need to even support updates for the APPID in
> > the first place. I understood it to be a unique identifier for
> > the VM from POV of the storage, and unique identifier are not
> > something you would typically change on the fly.
> 
> Good point, when implementing this feature I also thought that there is
> no need to have live changes, but to be sure I asked in the BZ (no
> public) and got an answer that they would like to have the live changes
> as well.

Reading the bug report I'm not convinced they are asking for live
changes. They are asking how to set the value using virsh, but
that doesn't imply live change. It is entirely possible, maybe even
likely, they just want to use 'virsh edit' to set the value in an
existing guest before booting it.

Regards,
Daniel
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