Re: [PATCH v1 05/12] libxl: add new hotplug interface support to hotplug script callers

["Roger Pau Monné" <roger.pau@citrix.com>]

On 13/03/13 15:53, Ian Jackson wrote:
> Roger Pau Monne writes ("[Xen-devel] [PATCH v1 05/12] libxl: add new hotplug interface support to hotplug script callers"):
>> Add support to call hotplug scripts that use the new hotplug interface
>> to the low-level functions in charge of calling hotplug scripts.
>>
>> libxl__prepare_ao_device sets the hotplug version to 1, in later
>> patches hotplug version will be set to 2 by the caller to use this
>> new hotplug calling convention.
> 
> I think this needs a comprehensive document describing the new calling
> convention.  Since there isn't currently a document describing the old
> calling convention I think you may need to do some reverse
> engineering.

Patch 11/12 adds a document describing the new calling convention.

> 
> And then when you do that, there are things about the old calling
> convention which are distinctly dodgy and should perhaps be changed.

I would prefer to avoid touching anything related to the old calling
convention, mainly because I would like to avoid touching the old
hotplug scripts in this series, and because there might be out-of-tree
hotplug scripts relaying on some of this obscure features.

> Is this autoprobing with the "version" argument really the best way to
> deal with compatibility ?  I guess we do know that it's reliable.

I think it's quite reliable, unless someone has an out-of-tree v1
hotplug script that implements this parameter, but I don't think this is
going to be the case.