Re: [Qemu-block] [Patch for-2.5 v2 5/6] qmp: add monitor command to add/remove a child

[Wen Congyang]

On 09/01/2015 11:34 PM, Eric Blake wrote:
> On 08/31/2015 06:55 PM, Wen Congyang wrote:
> 
>>>> +This command is still a work in progress. It doesn't support all
>>>> +block drivers. Stay away from it unless you want it to help with
>>>> +its development.
>>>
>>> Maybe we should name it 'x-child-add' for now, so that we aren't baking
>>> ourselves into a corner.
>>
>> Do you mean the command name should be x-child-add? It is OK.
> 
> Use of the 'x-' prefix means a command is experimental and may change or
> be withdrawn.  It gives us a way to test if an interface is useful
> without committing to that interface long term.  We've still got time
> before 2.5 to get blockdev-add working everywhere, in which case I think
> we are better off using blockdev-add to create a new unattached BDS and
> then have this command pass the node name to be made the new child,
> rather than all the options for opening the child from scratch.
> 

Good idea. The unattached BDS created by the command blockdev-add always
have BB. So it may be used by the device created by the command device_add
later. So I think we should have an API to check it. What about the following
patches?
http://lists.nongnu.org/archive/html/qemu-devel/2015-07/msg01591.html
http://lists.nongnu.org/archive/html/qemu-devel/2015-07/msg01590.html

Thanks
Wen Congyang