Re: [Qemu-devel] Re: [PATCH] qdev: Reject duplicate and anti-social device IDs

[Jan Kiszka]

Anthony Liguori wrote:
> On 06/01/2010 01:35 PM, Markus Armbruster wrote:
>> Luiz Capitulino<address@hidden>  writes:
>>
>>   
>>> On Tue, 01 Jun 2010 16:44:24 +0200
>>> Markus Armbruster<address@hidden>  wrote:
>>>
>>>     
>>>> Luiz Capitulino<address@hidden>  writes:
>>>>
>>>>       
>>>>> On Mon, 31 May 2010 16:13:12 +0200
>>>>> Markus Armbruster<address@hidden>  wrote:
>>>>>
>>>>>         
>>>>>> We need Device IDs to be unique and not contain '/' so device tree
>>>>>> nodes can always be unambigously referenced by tree path.
>>>>>>
>>>>>> We already have some protection against duplicate IDs, but it got
>>>>>> holes:
>>>>>>
>>>>>> * We don't assign IDs to default devices.
>>>>>>
>>>>>> * -device and device_add use the ID of a qemu_device_opts.  Which
>>>>>>    rejects duplicate IDs.
>>>>>>
>>>>>> * pci_add nic -net use either the ID or option "name" of
>>>>>>    qemu_net_opts.  And there's our hole.  Reproducible with "-net
>>>>>> user
>>>>>>    -net nic,id=foo -device lsi,id=foo".
>>>>>>            
>>>>>   Two bugs that might not be related to this thread:
>>>>>
>>>>>    * "id" member is not mandatory for the device_add command:
>>>>>
>>>>>      { "execute": "device_add", "arguments": { "driver": "e1000" } }
>>>>>      {"return": {}}
>>>>>          
>>>> Works as designed.
>>>>        
>>>   What about netdev_add?
>>>
>>>   { "execute": "netdev_add", "arguments": { "type": "user" } }
>>>   {"error": {"class": "MissingParameter", "desc": "Parameter 'id' is
>>> missing", "data": {"name": "id"}}}
>>>      
>> The only way to put a netdev to use is connecting it to a NIC with
>> -device DRIVER,netdev=ID,...  And that requires an ID.
>>    
> 
> To be honest, I think we should universally require an id parameter or
> we should auto-assign one and return it during creation.
> 
> Implicit/Null ids with QemuOpts are really difficult to work with and it
> certainly makes device addressing a lot easier.

I really see no need for this additional burden. We always have unique
qtree paths for devices.

Jan

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