Re: [Qemu-devel] [RFC PATCH 4/4] vhost-user: Add new option to specify vhost-user backend supports

[Tetsuya Mukawa <mukawa@igel.co.jp>]

On 2015/05/26 21:52, Eric Blake wrote:
> On 05/25/2015 10:29 PM, Tetsuya Mukawa wrote:
>
>>>>>  { 'struct': 'NetdevTapOptions',
>>>>> @@ -2259,7 +2261,8 @@
>>>>>      '*vhostfd':    'str',
>>>>>      '*vhostfds':   'str',
>>>>>      '*vhostforce': 'bool',
>>>>> -    '*queues':     'uint32'} }
>>>>> +    '*queues':     'uint32',
>>>>> +    '*backend_features':'uint64'} }
>>>> Ewww. Making users figure out what integers to pass is NOT user
>>>> friendly.  Better would be an enum type, and make the parameter an
>>>> optional array of enum values.
>>> Thanks for your comments. 
>>> I guess below may be good example. Is this same as your suggestion?
>>>
>>>  virtio-net-pci,netdev=hostnet3,id=net3,gso=off,guest_tso4=off,guest_tso6=off
>>>
>>> So I will improve 'backend-features' like below.
>>>
>>>  backend-features=gso=off,guest_tso4=off,guest_tso6=off
>>>
>>> Also I will fix 'qapi-schema.json' to work like above.
>> I seems it's impossible to implement like above.
>> I may need to implement like below.
>>
>> virtio-net-pci,netdev=hostnet3,id=net3,backend_gso=on,backend_guest_tso4=on,backend_guest_tso6=on
> Or even:
>
> virtio-net-pci,netdev=hostnet3,id=net3,backend.gso=on,backend.guest_tso4=on,backend.guest_tso6=on
>
> Look at -device for how to set up nested structs using '.' for a nice
> hierarchy of options all belonging to a common substruct.
>

I appreciate for your suggestion.
I will check '-device' option, and implement like above in v2 patch.

Tetsuya