[Qemu-devel] Re: Registering buffers with a qdict

[Jan Kiszka <jan.kiszka@siemens.com>]

Luiz Capitulino wrote:
> On Fri, 07 May 2010 16:21:13 +0200
> Jan Kiszka <jan.kiszka@siemens.com> wrote:
> 
>> Luiz Capitulino wrote:
>>> On Fri, 07 May 2010 13:45:03 +0200
>>> Jan Kiszka <jan.kiszka@siemens.com> wrote:
>>>
>>>> Hi Luiz,
>>>>
>>>> what is the recommended way of pushing larger buffers (up to 64K so far)
>>>> into a qdict? QLIST of QINT (one per byte) looks a bit heavy. I thought
>>>> about hex-encoding the content first (series of "%02X"), then
>>>> registering it as QSTRING. Or should we introduce a new type, QBUFFER?
>>>  I don't think that hex-encoding the contents is so bad if your use case is
>>> very specific and isolated.
>> The focus will be first on visualizing the buffer (user_print), but who
>> knows what happens once the services is also exposed via QMP.
>>
>>>  On the other hand, I do prefer a QBuffer type, specially because we can
>>> have buffer operations.
>> The q<type>.c files look sufficiently simply, guess I will add a buffer
>> type. Still, hex-encoding is probably the best representation for QMP.
> 
>  Yes, either as a string or (as suggested by Markus) an array of numbers,
> if you wish to expose this via QMP you (or any of us) will have to update
> the parser to support it.

>From a quick glance at the JSON spec, there is no room for a new type. I
think we have to overload an existing one and convert that into a
QBuffer (typically, we know the actual semantic). Hex string encoding is
most compact, so I went this road. But I'm open to change it into a true
type if JSON actually allows it (or we are fine with breaking it).

Jan

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