Re: [PATCH v3 00/30] qapi/qom: QAPIfy --object and object-add

From: Paolo Bonzini <pbonzini@redhat.com>
To: Markus Armbruster <armbru@redhat.com>, Kevin Wolf <kwolf@redhat.com>
Cc: lvivier@redhat.com, thuth@redhat.com,
	Peter Krempa <pkrempa@redhat.com>,
	ehabkost@redhat.com, qemu-block@nongnu.org,
	libvir-list@redhat.com, jasowang@redhat.com,
	qemu-devel@nongnu.org, mreitz@redhat.com, kraxel@redhat.com,
	dgilbert@redhat.com
Subject: Re: [PATCH v3 00/30] qapi/qom: QAPIfy --object and object-add
Date: Thu, 11 Mar 2021 12:00:12 +0100	[thread overview]
Message-ID: <e98a5eb7-4716-a0f4-0ad2-adaa4cd9cefa@redhat.com> (raw)
In-Reply-To: <87ft12q8kf.fsf@dusky.pond.sub.org>

On 11/03/21 11:38, Markus Armbruster wrote:
> Here's a differently terrible hack.  We have
> 
>           keyval_parse()       visitor
>      optarg --------> QObject --------> QAPI type
> 
> Idea: hack the QObject.  If we're working for -object, and QObject maps
> key "qom-type" to value "memory-backend-ram", get the value of
> host-nodes, and if it's a string, parse it into a list like the opts
> visitor does, and put that back, replacing the string value.
> 
> Same for other uses of Memdev and NumaNodeOptions with -object, if they
> exist.

This doesn't help with backwards compatibility, since keyval loses the 
first of host-nodes=0,host-nodes=4.

I would rather keep the OptsVisitor here.  Do the same check for JSON 
syntax that you have in qobject_input_visitor_new_str, and whenever you 
need to walk all -object arguments, use something like this:

     typedef struct ObjectArgument {
         const char *id;
         QDict *json;    /* or NULL for QemuOpts */
         QSIMPLEQ_ENTRY(ObjectArgument) next;
     }

I already had patches in my queue to store -object in a GSList of 
dictionaries, changing it to use the above is easy enough.

Paolo