From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:55794)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <wdongxu@linux.vnet.ibm.com>) id 1UUSIa-0001q6-OJ
	for qemu-devel@nongnu.org; Mon, 22 Apr 2013 21:45:38 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <wdongxu@linux.vnet.ibm.com>) id 1UUSIZ-0006nx-Rd
	for qemu-devel@nongnu.org; Mon, 22 Apr 2013 21:45:36 -0400
Received: from e36.co.us.ibm.com ([32.97.110.154]:38421)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <wdongxu@linux.vnet.ibm.com>) id 1UUSIZ-0006nq-Kv
	for qemu-devel@nongnu.org; Mon, 22 Apr 2013 21:45:35 -0400
Received: from /spool/local
	by e36.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only!
	Violators will be prosecuted
	for <qemu-devel@nongnu.org> from <wdongxu@linux.vnet.ibm.com>;
	Mon, 22 Apr 2013 19:45:34 -0600
Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com
	[9.17.195.227])
	by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id E5D9F19D8042
	for <qemu-devel@nongnu.org>; Mon, 22 Apr 2013 19:45:26 -0600 (MDT)
Received: from d03av06.boulder.ibm.com (d03av06.boulder.ibm.com [9.17.195.245])
	by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id
	r3N1jVPC134348
	for <qemu-devel@nongnu.org>; Mon, 22 Apr 2013 19:45:32 -0600
Received: from d03av06.boulder.ibm.com (loopback [127.0.0.1])
	by d03av06.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP
	id r3N1mNjr018330
	for <qemu-devel@nongnu.org>; Mon, 22 Apr 2013 19:48:23 -0600
Message-ID: <5175E7BB.8010402@linux.vnet.ibm.com>
Date: Tue, 23 Apr 2013 09:45:31 +0800
From: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
MIME-Version: 1.0
References: <1365581513-3475-1-git-send-email-wdongxu@linux.vnet.ibm.com>
	<1365581513-3475-2-git-send-email-wdongxu@linux.vnet.ibm.com>
	<20130418083029.GA19587@stefanha-thinkpad.redhat.com>
In-Reply-To: <20130418083029.GA19587@stefanha-thinkpad.redhat.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH V18 1/6] docs: document for add-cow file
 format
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: kwol@redhat.com, wdongxu@cn.ibm.com, qemu-devel@nongnu.org, stefanha@redhat.com

On 2013/4/18 16:30, Stefan Hajnoczi wrote:
> On Wed, Apr 10, 2013 at 04:11:48PM +0800, Dong Xu Wang wrote:
>> +The Header is included in the first bytes:
>> +(HEADER_SIZE is defined in 40-43 bytes.)
>> +    Byte    0  -  3:    magic
>> +                        add-cow magic string ("ACOW").
>> +
>> +            4  -  7:    backing file name offset
>> +                        Offset in the add-cow file at which the backing
>> +                        file name is stored (NB: The string is not
>> +                        lNUL-terminated).
>
> s/lNUL/NUL/
Okay.
>
>> +            24 - 31:    features
>> +                        Bitmask of features. If a feature bit is set
>> +                        but not recognized, the add-cow file should be
>> +                        dropped. They are not used in now.
>
> "If a feature bit is set but not recognized, the opening the add-cow file must fail.  No features bits are currently defined."
>
Okay.
>