Re: [Qemu-devel] [PATCH 8/8] qom: Make CPU a child of DeviceState

["Andreas Färber" <afaerber@suse.de>]

Am 12.12.2012 15:27, schrieb Igor Mammedov:
> On Wed, 12 Dec 2012 11:59:01 -0200
> Eduardo Habkost <ehabkost@redhat.com> wrote:
>> On Wed, Dec 12, 2012 at 02:34:08PM +0100, Andreas Färber wrote:
>>> This patch makes the CPU a device and looks good so far but does not
>>> initialize the devices in cpu_*_init() like Anthony did in his previous
>>> patch. I am unsure whether you forgot to do so or whether you wanted to
>>> help keep our new CPU code clean of old-style qdev_init_nofail() calls?
>>> Since you don't add a qdev initfn here the main difference will be the
>>> devices internally staying in "created" rather than "initialized" state.
>>
>> I think I used a version without the qdev_init_nofail() as base for this
>> series (we had multiple proposals being sent in parallel, in the
>> beginning), and in the end I forgot that we had a version with those
>> calls being added.
>>
>> The CPU classes don't set any DeviceClass.init() method, so in theory
>> the missing qdev_init() calls wouldn't make any difference by now. On
>> the other hand, keeping the device in "created" state sounds bad... but
>> maybe this acceptable while we are still converting the CPU realize()
>> functions to fit inside the DeviceState initialization abstraction?
> Testing shows that lack of qdev_create()/init() doesn't break anything so
> far.

The latest motivation for making the CPU a device was to have the static
properties infrastructure for machine/CPU versioning. The global
property defaults are set in qdev's instance_init, so object_new() seems
fine for that.

qdev_[try_]create() would further set the parent bus to SysBus if NULL.
The CPU is not a SysBusDevice so I think not using qdev_create() may be
safer... Maybe Anthony or Paolo can confirm?

Andreas

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