Re: [Qemu-devel] Re: [PATCH 00/15] QAPI Round 1 (core code generator) (v2)

[Anthony Liguori <anthony@codemonkey.ws>]

On 03/16/2011 10:00 AM, Luiz Capitulino wrote:
> On Wed, 16 Mar 2011 15:49:59 +0100
> Paolo Bonzini<pbonzini@redhat.com>  wrote:
>
>> On 03/16/2011 03:34 PM, Luiz Capitulino wrote:
>>> +##
>>> +# @put_event:
>>> +#
>>> +# Disconnect a signal.  This command is used to disconnect from a signal based
>>> +# on the handle returned by a signal accessor.
>>> +#
>>> +# @tag: the handle returned by a signal accessor.
>>> +#
>>> +# Returns: Nothing on success.
>>> +#          If @tag is not a valid handle, InvalidParameterValue
>>> +#
>>> +# Since: 0.15.0
>>>
>>> The name 'signal' (at least today) doesn't make sense on the wire protocol,
>>> 'put_event' probably doesn't make sense in the C library, nor does 'event'.
>>>
>>> Another detail is that, event extension is more important than command
>>> extension, because it's probably going to happen. I think it would be very
>>> bad to add new events just because we wanted to add a new field.
>> What if events were always passed a single struct, with the first field
>> being a bitmask saying which (or how many) fields have been filled?
>>
>> It is quite ugly to work that way when calling functions, but it's not
>> too bad when you are writing the callees.  And it's the code generator
>> that writes the function calls in the case of libqmp...
> I was also wondering if it's possible to only make the most recent version
> available in the wire protocol and all existing ones in libqmp.

I don't quite follow.

libqmp works with all previous versions of QMP.  New functions will 
return a CommandNotFound error.

In fact, you can run test-libqmp -p /0.14 and it will run the 
regressions against the QMP server shipped in 0.14[1].  This is why I 
used version prefixes :-)

[1] test-libqmp right now doesn't have a way to select which method you 
use for connecting to the QMP server and right now assumes a unix socket 
at a well known location.  It doesn't add the right parameter to QEMU to 
launch this way because in my tree, this is all implicit so you need to 
patch test-libqmp to explicitly add that qmp socket.

Regards,

Anthony Liguori