Re: [PATCH] PoC: Rust binding for QAPI (qemu-ga only, for now)

[Paolo Bonzini]

On 21/09/20 11:16, Markus Armbruster wrote:
> QMP is an *external* interface.
> 
> It supports compatible evolution: we can make certain kinds of changes
> without affecting clients.  These include:
> 
> * Adding optional arguments
> 
> * Adding results
> 
> * Adding values to an enumeration type, branches to a union or
>   alternate
> 
> * Reordering members of enumerations, structs, unions
> 
> * Turning an argument type into an alternate with the old type as branch
> 
> We've made use of this extensively.  See also
> docs/devel/qapi-code-gen.txt section "Compatibility considerations."
> 
> How do such changes affect clients of the proposed D-Bus interface?

All this makes me think that Q{MP,OM,API} badly needs rationale
documentation.

Paolo