From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1Lru5W-0007K2-FB
	for qemu-devel@nongnu.org; Thu, 09 Apr 2009 09:14:38 -0400
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1Lru5R-0007IA-SH
	for qemu-devel@nongnu.org; Thu, 09 Apr 2009 09:14:38 -0400
Received: from [199.232.76.173] (port=37592 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1Lru5R-0007I3-H5
	for qemu-devel@nongnu.org; Thu, 09 Apr 2009 09:14:33 -0400
Received: from yw-out-1718.google.com ([74.125.46.158]:10377)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <anthony@codemonkey.ws>) id 1Lru5R-000503-B5
	for qemu-devel@nongnu.org; Thu, 09 Apr 2009 09:14:33 -0400
Received: by yw-out-1718.google.com with SMTP id 9so362481ywk.82
	for <qemu-devel@nongnu.org>; Thu, 09 Apr 2009 06:14:32 -0700 (PDT)
Message-ID: <49DDF4B4.1050609@codemonkey.ws>
Date: Thu, 09 Apr 2009 08:14:28 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] buffer alignment for block backends
References: <49DCA80A.1020808@eu.citrix.com> <49DCF2C0.9070704@codemonkey.ws>
	<49DDC8E0.50900@eu.citrix.com>
In-Reply-To: <49DDC8E0.50900@eu.citrix.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Reply-To: qemu-devel@nongnu.org
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: qemu-devel@nongnu.org

Stefano Stabellini wrote:
> Anthony Liguori wrote:
>
>   
>>> If you do not want to do that, another possible solution is to create a
>>> new function called "qemu_blockalign" that would be implemented as
>>> qemu_memalign(512, size);
>>>       
>> This is fine, but this is purely an optimization, it cannot be relied 
>> upon in the general case.
>>
>>     
>
>
>
> If you are OK with this, a simple patch like the following is
> acceptable, or do you prefer a more formal approach involving a new
> function in the BlockDriver interface?
>   

Yes, but that's not covering very many of the cases.  There are still 
places where we allocate bounce buffers that aren't with memalign (like 
in block-qcow2.c).  Also, please document what the new function does and 
when it should be used.

Regards,

Anthony Liguori