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

[Stefan Hajnoczi]

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.

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