From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from [140.186.70.92] (port=48546 helo=eggs.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1OZ75D-0002GY-PO
	for qemu-devel@nongnu.org; Wed, 14 Jul 2010 14:53:28 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69)
	(envelope-from <anthony@codemonkey.ws>) id 1OZ75C-000424-72
	for qemu-devel@nongnu.org; Wed, 14 Jul 2010 14:53:27 -0400
Received: from mail-gy0-f173.google.com ([209.85.160.173]:61055)
	by eggs.gnu.org with esmtp (Exim 4.69)
	(envelope-from <anthony@codemonkey.ws>) id 1OZ75B-00041v-V8
	for qemu-devel@nongnu.org; Wed, 14 Jul 2010 14:53:26 -0400
Received: by gyf2 with SMTP id 2so70180gyf.4
	for <qemu-devel@nongnu.org>; Wed, 14 Jul 2010 11:53:25 -0700 (PDT)
Message-ID: <4C3E07A2.70907@codemonkey.ws>
Date: Wed, 14 Jul 2010 13:53:22 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH] Make default invocation of block drivers
	safer
References: <1279123952-1576-1-git-send-email-aliguori@us.ibm.com>
	<20100714184311.GA9383@lst.de>
In-Reply-To: <20100714184311.GA9383@lst.de>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
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.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: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Christoph Hellwig <hch@lst.de>
Cc: Kevin Wolf <kwolf@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

On 07/14/2010 01:43 PM, Christoph Hellwig wrote:
> Err, strong NACK.  Please don't start messing with the contents of the
> data plane, we're getting into real trouble there.  It's perfectly
> valid for a guest to create an image inside an image, and with hardware
> support for nested virtualization I guess this use case will become
> rather common, just as it already is on S/390 with VM.
>    

Note, this is limited to raw.

If you use qcow2 in L0, the guest can do whatever it wants to do.

But if we autoprobe a raw image, we simply cannot let a guest turn the 
raw image into something else.

A user can still use raw images and let them contain anything, but they 
have to explicitly specify that it's a raw image.

Regards,

Anthony Liguori