Re: [PATCH 00/15] hw: expand DEFINE_MACHINE to explicit TypeInfo registration

[Yonggang Luo <luoyonggang@xxxxxxxxx>]

On Tue, Nov 3, 2026 at 4:16 PM Daniel P. Berrangé <berrange@xxxxxxxxxx> wrote:
>
> On Fri, Oct 30, 2026 at 05:51:44PM -0800, Pierrick Bouvier wrote:
> > On 10/30/2026 4:09 PM, BALATON Zoltan wrote:
> > > On Fri, 30 Oct 2026, Yonggang Luo wrote:
> > >> DEFINE_MACHINE and DEFINE_MACHINE_EXTENDED hide the TypeInfo and the
> > >> type_init
> > >> function that calls type_register_static(). A later change needs to
> > >> pass a
> > >
> > > That's the point of the macro to hide the boiler plate code.
> > >
> > >> target mask into that registration, and the macros have no parameter
> > >> for it.
> > >
> > > Couldn't you just change the macros to take that parameter instead of
> > > expanding it everywhere?
> > >
> >
> > Problem of macros is that they don't have default parameters, so you
> > need variants for everything:
> >
> > DEFINE_MACHINE
> > DEFINE_MACHINE_EXTENDED
> > DEFINE_MACHINE_WITH_INTERFACES
> > DEFINE_MACHINE_WITH_INTERFACE_ARRAY
> > and now would need a new variant, with variant for other existing ones.
> >
> > In the end, it's just simpler to remove this and add the boilerplate.
> > It's written once and never modified, so using a macro just save typing
> > those lines once.
>
> For each machine, it is only written once, but we add machines
> over time, and every time a new machine is added the code style
> is slightly different. We introduced all the variuos DEFINE_*
> macros for QOM to better ensure consistent style and usage as
> new code is added over time.

I understand that the DEFINE_* macros are bloating because of this.
Indeed currently the only two macros used are "DEFINE_MACHINE" and
"DEFINE_MACHINE_EXTENDED"
; each time people want to add a new attribute, the macros is twiced.
And the usage of DEFINE_MACHINE_EXTENDED is rare and can be replaced
with DEFINE_TYPES or TypeInfo
and be more explicit. When we used as macro parameter, we need think
what's that parameter means, and for
TypeInfo, we can directly know what that member is about(because we
are assigned with the member name).
That's why I suggest keeping a single DEFINE_MACHINE, just like
DEFINE_TYPES; as they are the most
used macros(and simple enough), and won't suffer from changes much.

>
> With regards,
> Daniel
> --
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>


-- 
         此致
礼
罗勇刚
Yours
    sincerely,
Yonggang Luo