Re: [RFC PATCH v3 16/19] qmp: add query-cpu-props-info command

Khushit Shah <[email protected]> writes:

> Introduce the 'query-cpu-props-info' QMP command. For CPU model
> properties it reports the type (boolean or number) and the set of values
> supported under the active accelerator and host.
>
> For numbers the supported values are expressed as a list of inclusive
> {min, max} ranges; for booleans as the list of allowed true/false
> values.
>
> The command and its return types (CpuPropertyType, CpuPropertyInfo and
> friends) are defined in qapi/machine.json rather than an Arm-specific
> schema, since the concept applies to other targets (e.g. x86, riscv)
> too. Target that do not implement it return an error.
>
> The Arm/KVM implementation spins up a scratch "host" vCPU object,
> walks its QOM properties: SYSREG_ ID-register fields become 'number'
> properties whose ranges come from arm_field_get_supported_values(),
> and the advertised feature toggles become 'boolean' properties.
>
> Signed-off-by: Khushit Shah <[email protected]>

This explains what the command does and how it's implemented.  It's
silent on the most important aspect: why do we want the command?  What
is its intended purpose?