Re: [Qemu-devel] [PATCH] qdev: Fix qdev_try_create() for bus-less devices

[Andreas Färber]

Am 05.02.2014 17:46, schrieb Andreas Färber:
> Am 05.02.2014 17:38, schrieb Paolo Bonzini:
>> Il 05/02/2014 15:09, Andreas Färber ha scritto:
>>> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
>>> index 82a9123..14c8765 100644
>>> --- a/hw/core/qdev.c
>>> +++ b/hw/core/qdev.c
>>> @@ -131,21 +131,27 @@ DeviceState *qdev_create(BusState *bus, const
>>> char *name)
>>>  DeviceState *qdev_try_create(BusState *bus, const char *type)
>>>  {
>>>      DeviceState *dev;
>>> +    ObjectClass *oc;
>>> +    DeviceClass *dc;
>>>
>>> -    if (object_class_by_name(type) == NULL) {
>>> +    oc = object_class_by_name(type);
>>> +    if (oc == NULL) {
>>>          return NULL;
>>>      }
>>> +    dc = DEVICE_CLASS(oc);
>>>      dev = DEVICE(object_new(type));
>>>      if (!dev) {
>>>          return NULL;
>>>      }
>>>
>>> -    if (!bus) {
>>> +    if (!bus && dc->bus_type && strcmp(dc->bus_type, "System") == 0) {
>>
>> Should you check instead if dev is-a TYPE_SYSBUS_DEVICE?
> 
> Hmm, that would catch TYPE_SYS_BUS_DEVICE-derived types as well, which
> might in theory override bus_type.
> 
> The ugly thing here is the cyclic dependency betwen qdev and sysbus,
> therefore no TYPE_SYSTEM_BUS.

BTW this patch became optional due to the one-line nand fix (which also
does not show the device in legacy info qtree), but I am still in favor
of merging this or a variation thereof to avoid future troubles.

Andreas

> 
>> Does this also leave the nand device out of info qtree, or is it still
>> dumped?
> 
> As I pointed out several times already, devices that are not on a bus
> are generally *not* printed by info qtree. It depends on the old qbus
> concept. Therefore info qtree is not of much use anymore and should be
> dropped in favor of the qom-list and qom-get operations, which get us
> all devices and all properties. I had once attached a qom-tree for that
> and need to put that into a proper patch. Best before the next question
> pops up. :)
> 
> Andreas
> 


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