Re: [Xen-devel] [PATCH v1 07/12] libxl: add prepare/unprepare operations to the libxl public interface

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Roger Pau Monne writes ("Re: [Xen-devel] [PATCH v1 07/12] libxl: add 
prepare/unprepare operations to the libxl public interface"):
> On 13/03/13 17:19, Ian Jackson wrote:
> > I'm not sure I understand how the caller is supposed to use this.
> 
> The caller should execute prepare before adding the disk (hopefully in a
> not performance sensitive path).

That's a non-backward-compatible API change, then ?  We're trying to
avoid those.

> > How does the eventual script manage to correlate the preparation with
> > the unpreparation ?
> 
> You call the script with the prepare or unprepare parameters, so the
> script knows which action it has to execute.

No, I mean, is it just the target string that is relevant for
identifying the preparation ?  Can the same disk be prepared multiple
times (eg for multiple guests) ?  How is this synchronised ?

> The only downfall of not calling prepare before add is that libxl will
> thread this device as using the v1 hotplug interface, so old users of
> libxl will still have the same functionality, but they will not be able
> to use new hotplug scripts using the v2 interface.

Perhaps it would be better to hide this from the caller and implement
the old API in terms of the new one ?

ian.

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