Re: [PATCH V5 3/7] libxl: add pvusb API

[George Dunlap <george.dunlap@citrix.com>]

On 08/07/2015 03:31 AM, Chun Yan Liu wrote:
>>>>>> +    ("devid", libxl_devid),   
>>>>>> +    ("version", integer),   
>>>>>> +    ("ports", integer),   
>>>>>> +    ("backend_domid", libxl_domid),   
>>>>>> +    ("backend_domname", string),   
>>>>>> +   ])   
>>>>>> +   
>>>>>> +libxl_device_usb = Struct("device_usb", [   
>>>>>> +    ("ctrl", libxl_devid),   
>>>>>> +    ("port", integer),   
>>>>>> +    ("hostbus",   integer),   
>>>>>> +    ("hostaddr",  integer),   
>>>>>> +    ])   
>>  
>> I think we do want to plan for the future here by doing something like this: 
>>  
>> libxl_device_usb = Struct("device_usb", [ 
>>     ("ctrl", libxl_devid), 
>>     ("port", integer), 
>>     ("u", KeyedUnion(None, libxl_device_usb_type, "devtype", 
>>                       [("hostdev", Struct(None, [ 
>>                              ("hostbus",   integer), 
>>                              ("hostaddr",  integer) ])) 
>>                        ])) 
>>  ]) 
>>  
> 
> Yes, that's the future look. For pvusb, currenlty with kernel pvusb driver, the
> devtype is not really necessary. But I can add 'devtype' if it is preferred now.

Yes, I think as much as possible we want the interface which is actually
checked in to be forward-compatible.

Thanks!
 -George