On 7/29/20 2:32 PM, Markus Armbruster wrote:
> Philippe Mathieu-Daudé <[email protected]> writes:
>
>> On 7/29/20 9:39 AM, Markus Armbruster wrote:
>>> Paolo Bonzini <[email protected]> writes:
>>>
>>>> On 28/07/20 09:44, Markus Armbruster wrote:
>>>>>> - assert(!DEVICE_GET_CLASS(dev)->bus_type);
>>>>>> + } else if (DEVICE_GET_CLASS(dev)->bus_type) {
>>>>>> + error_setg(errp, "Unexpected bus '%s' for bus-less device '%s'",
>>>>>> + DEVICE_GET_CLASS(dev)->bus_type,
>>>>>> + object_get_typename(OBJECT(dev)));
>>>>>> + return false;
>>>>>> }
>>>>>>
>>>>>> object_property_set_bool(OBJECT(dev), true, "realized", &err);
>>>>> Objection. This turns an abort into something else unless the caller
>>>>> passes &error_abort. The caller in your commit message's example does,
>>>>> others don't.
>>>>>
>>>>> Keep the unconditional abort, please. Feel free to print something kind
>>>>> right before. I doubt it's all that useful, as I believe whoever gets
>>>>> to fix the bug will have to figure out the code anyway, but I could be
>>>>> wrong.
>>>>>
>>>>
>>>> This was my request, actually. We have an Error**, we should use it in
>>>> case this code is reached via device_add.
>>>
>>> That's not actually possible.
>>
>> I agree this condition is not possible in current mainstream.
>>
>> What I'm working on is:
>>
>> qmp command that:
>> - create a SDCard or FloppyDisk medium
>> - eventually link a block driver to it
>> - insert the medium into a slot
>>
>> then another qmp command that
>> - eject the medium
>> - unlink the block driver
>> - destroy the medium
>>
>> second step is a command that takes as argument
>> (block driver, bus endpoint) and automatically
>> creates the envelope media and insert it to the bus.
>
> If this makes the error possible, then your code fails to establish
> qdev_realize()'s precondition, and therefore needs fixing.
Yes, because I try to create a bus-ful device without plugging it on
the bus (I want to set the block driver link before plugging it).
>
> Could a combination of existing commands get the job done?
Maybe. I'm trying a clean design. With the current state it is hard
to figure if my design is broken or the current QEMU design [*] is
broken and unfixable.
[*] keep re-using existing media device, add blockdrv, reset media
device internals register depending of the blockdrv properties,
eject blockdrv/insert different one and keep adapting the device.
