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