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From: Markus Armbruster <armbru@redhat.com>
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	<20170707081305.GA15945@redhat.com>
Date: Fri, 07 Jul 2017 11:00:02 +0200
In-Reply-To: <20170707081305.GA15945@redhat.com> (Daniel P. Berrange's message
	of "Fri, 7 Jul 2017 09:13:05 +0100")
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Subject: Re: [Qemu-devel] [PATCH v22 25/30] qmp: add
 x-debug-block-dirty-bitmap-sha256
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To: "Daniel P. Berrange" <berrange@redhat.com>
Cc: kwolf@redhat.com, Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>, famz@redhat.com, qemu-block@nongnu.org, qemu-devel@nongnu.org, mreitz@redhat.com, stefanha@redhat.com, pbonzini@redhat.com, den@openvz.org, jsnow@redhat.com

"Daniel P. Berrange" <berrange@redhat.com> writes:

> On Fri, Jul 07, 2017 at 10:05:22AM +0200, Markus Armbruster wrote:
>> Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> writes:
>> 
>> > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> > ---
>> >  block/dirty-bitmap.c         |  5 +++++
>> >  blockdev.c                   | 25 +++++++++++++++++++++++++
>> >  include/block/dirty-bitmap.h |  1 +
>> >  include/qemu/hbitmap.h       |  8 ++++++++
>> >  qapi/block-core.json         | 27 +++++++++++++++++++++++++++
>> >  tests/Makefile.include       |  2 +-
>> >  util/hbitmap.c               | 11 +++++++++++
>> >  7 files changed, 78 insertions(+), 1 deletion(-)
>> [...]
>> > diff --git a/qapi/block-core.json b/qapi/block-core.json
>> > index 5c42cc7790..6ad8585400 100644
>> > --- a/qapi/block-core.json
>> > +++ b/qapi/block-core.json
>> > @@ -1644,6 +1644,33 @@
>> >    'data': 'BlockDirtyBitmap' }
>> >  
>> >  ##
>> > +# @BlockDirtyBitmapSha256:
>> > +#
>> > +# SHA256 hash of dirty bitmap data
>> > +#
>> > +# @sha256: ASCII representation of SHA256 bitmap hash
>> 
>> Spell it SHA-256, please.  The member name @sha256 can stay.
>> 
>> SHA-256 is 256 binary bits.  Please specify how they are represented in
>> ASCII.  It better be base64 (RFC 4648), because we use that elsewhere.
>
> It is filled later in this patch using qcrypto_hash_digest, so it is just
> a hex string representing the hash, not base64. For the latter you can
> use qcrypto_hash_base64

I got two points:

1. Whatever encoding we use, it needs to be documented.

2. The fewer binary -> ASCII encodings we use, the better.  We already
use base64.