Re: [PATCH-for-9.1 09/21] qapi: Merge machine-common.json with qapi/machine.json

[Markus Armbruster]

Philippe Mathieu-Daudé <philmd@linaro.org> writes:

> machine-common.json declares a single type, which isn't
> restricted to a particular target. Move this type in
> machine.json.
>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Previous discussion at
https://lore.kernel.org/qemu-devel/875y45kt8i.fsf@pond.sub.org/

CpuS390Entitlement is specific to s390x.  We need it for
set-cpu-topology and the s390x-specific part of query-cpus-fast.  The
former is conditional on TARGET_S390X, and therefore must be in
machine-target.json.  The latter is not conditional, and in
machine.json.  If I remember correctly, I briefly explored making it
conditional, but it was too messy to be worth the bother.

Anyway.  We have a target-specific type we want to use both in
machine.json and machine-target.json.  Neither of the two includes the
other.  Target-independent machine.json cannot include target-specific
machine-target.json.  Two solutions:

1. Define the type in machine.json, have machine-target.json include
machine.json.  Ugly: even more target-stuff in machine.json.
Potentially slow: including qapi/qapi-*-machine-target.h now includes
more.

2. Define the type in a submodule both include.  Since nothing they
include is a fitting home for the type, create one: machine-common.json.
Ugly & potentially slow: yet another submodule.

Nina chose to do 2.

I figure I'd leave it as is until we get to the point where we can get
rid of the *-target.json entirely.