On Tue, Aug 15, 2017 at 01:57:50PM -0500, Eric Blake wrote:
> On 08/14/2017 04:57 PM, Eduardo Habkost wrote:
> > Changelog
> > ---------
> >
> > Changes v3 -> v4:
> > * New compact representation of slot sets.
> > * New generic code to automatically merge similar slots
> > into a single entry in the command output while keeping
> > implementations of the method simpler.
> > * Example implementation of IDE and USB bus enumeration
>
> >
> > Slot sets are represented by a list of option names and sets of
> > possible values for each of those options. The command uses a
> > compact representation for the set of valid values for an option.
> > For example, the following set of 5 PCI functions:
> >
> > bus: pcie.0
> > device-number: 31
> > functions: 1,4,5,6,7
> >
> > would be represented in the JSON data as:
> >
> > {"available":false,"count":5,
> > "device-types":["pci-device"],"hotpluggable":false,
> > "opts":[
> > {"option":"function","values":[1,[4,7]]},
>
> A list (and not just a single-type list, but a list that mixes scalar
> and sublist),
>
> > {"option":"device-number","values":31},
>
> vs. a scalar. Why not a one-element array?
It was just to keep the representation as compact as possible, in
the common case of single-value sets. Probably we can drop that
feature as it saves only 2 bytes in the JSON representation.
>
> > {"option":"bus","values":"pcie.0"}],
> > "opts-complete":true}
> >
> > I planned to use QAPI alternates to model/document that in the
> > schema, but it would require implementing a few missing features
> > in QAPI alternate support.
>
> Yeah, I can see how existing QAPI alternates do not yet support arrays,
> which becomes important to your representation. Do you need help
> getting the QAPI generator improved to support a particular feature that
> you found to be lacking?
I think the lack of support for lists on alternates was the main
obstacle.
Probably we would also need to remove the restriction against
alternates with ambiguous string representations, to allow a
list/number/string/bool alternate to be defined.
Being able to set constraints on the number of elements of a list
would be nice to have, but not required.
--
Eduardo
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