Re: How to mark internal properties (was: Re: [PATCH v4 12/27] target/i386/cpu: Remove CPUX86State::enable_cpuid_0xb field)

["Daniel P. Berrangé" <berrange@redhat.com>]

On Mon, May 12, 2025 at 09:46:30AM +0100, Peter Maydell wrote:
> On Fri, 9 May 2025 at 11:04, Thomas Huth <thuth@redhat.com> wrote:
> > Thanks for your clarifications, Zhao! But I think this shows again the
> > problem that we have hit a couple of times in the past already: Properties
> > are currently used for both, config knobs for the users and internal
> > switches for configuration of the machine. We lack a proper way to say "this
> > property is usable for the user" and "this property is meant for internal
> > configuration only".
> >
> > I wonder whether we could maybe come up with a naming scheme to better
> > distinguish the two sets, e.g. by using a prefix similar to the "x-" prefix
> > for experimental properties? We could e.g. say that all properties starting
> > with a "q-" are meant for QEMU-internal configuration only or something
> > similar (and maybe even hide those from the default help output when running
> > "-device xyz,help" ?)? Anybody any opinions or better ideas on this?
> 
> I think a q-prefix is potentially a bit clunky unless we also have
> infrastructure to say eg DEFINE_INTERNAL_PROP_BOOL("foo", ...)
> and have it auto-add the prefix, and to have the C APIs for
> setting properties search for both "foo" and "q-foo" so you
> don't have to write qdev_prop_set_bit(dev, "q-foo", ...).

I think it is also not obvious enough that a 'q-' prefix means private.

Perhaps borrow from the C world and declare that a leading underscore
indicates a private property. People are more likely to understand and
remember that, than 'q-'.

With regards,
Daniel
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