Re: [RFC QEMU PATCH] ui: Make the DisplayType enum entries conditional

[Markus Armbruster]

Gerd Hoffmann <kraxel@redhat.com> writes:

>   Hi,
>
>> > The #if CONFIG_SDL approach will not work because qemu will continue to
>> > report sdl as supported even when the sdl module is not installed any
>> > more.
>> 
>> I guess we'd need a separate QMP command to fix that, which tries to load
>> the modules first when being called? Something similar to what is being done
>> in qemu_display_help() ?
>
> That would work, yes.
>
>> That's certainly doable, too, just a little bit more complex...
>
> Alternative idea: turn QemuDisplay into an ObjectClass, then it'll be
> visible in qom introspection.  Likewise a bit more complex ...
>
>> do we want that?  Or is the quick-n-easy way via the schema good
>> enough for most use cases?
>
> Would be better than nothing, but I'd prefer something which works
> properly with modular qemu ...

Define "properly" :)

Without modules, qom-list-types has no side-effects, as introspection
should be.  With modules, it loads *all* modules known to define QOM
types, running their initialization code.

It loads them all even when asked to list only some, with argument
"implements".

In theory, management applications not having to know anything about
modules is nice.  Whether it'll work out in practice remains to be seen.
I'm not exactly confident.

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