Re: [Qemu-devel] [PATCH 1/8] spec: add qcow2-dirty-bitmaps specification

[John Snow]

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On 06/11/2015 09:03 AM, Stefan Hajnoczi wrote:
> On Thu, Jun 11, 2015 at 01:19:24PM +0300, Vladimir
> Sementsov-Ogievskiy wrote:
>> On 10.06.2015 16:24, Stefan Hajnoczi wrote:
>>> On Wed, Jun 10, 2015 at 11:19:30AM +0300, Vladimir
>>> Sementsov-Ogievskiy wrote:
>>>> On 09.06.2015 20:03, Stefan Hajnoczi wrote:
>>>>> On Mon, Jun 08, 2015 at 06:21:19PM +0300, Vladimir
>>>>> Sementsov-Ogievskiy wrote:
>>>>>> @@ -166,6 +167,19 @@ the header extension data. Each
>>>>>> entry look like this: terminated if it has full length) 
>>>>>> +== Dirty bitmaps == + +Dirty bitmaps is an optional
>>>>>> header extension. It provides a possibility of +storing
>>>>>> dirty bitmaps in qcow2 image. The fields are: + +
>>>>>> 0 -  3:  nb_dirty_bitmaps +                   Number of
>>>>>> dirty bitmaps contained in the image
>>>>> Is there a maximum?
>>>> hmm. any proposals for this?
>>> 65535 seems practical.
>> 
>> So, you suggest to reduce this field width to 2b? And additional
>> 2 bytes reserved field, to achieve 8b-alignment?
> 
> No, I would leave it 32-bit but impose a little (which can be
> increased later if necessary).  That's how nb_snapshots works too.
> 

Doesn't the code already limit the number of bitmaps via +#define
QCOW_MAX_DIRTY_BITMAPS 65536, from patch 2?
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