From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1MGcBI-0002LU-Bs
	for qemu-devel@nongnu.org; Tue, 16 Jun 2009 13:10:44 -0400
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1MGcBF-0002Kg-0Q
	for qemu-devel@nongnu.org; Tue, 16 Jun 2009 13:10:44 -0400
Received: from [199.232.76.173] (port=41402 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1MGcBE-0002Kd-Qn
	for qemu-devel@nongnu.org; Tue, 16 Jun 2009 13:10:40 -0400
Received: from smtp.citrix.com ([66.165.176.89]:48472)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <Stefano.Stabellini@eu.citrix.com>)
	id 1MGcBE-0002qg-Cz
	for qemu-devel@nongnu.org; Tue, 16 Jun 2009 13:10:40 -0400
Message-ID: <4A37D30D.40003@eu.citrix.com>
Date: Tue, 16 Jun 2009 18:14:53 +0100
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] Regression opening read-only cdroms
References: <4A37896C.8050208@redhat.com>	<20090616143259.GA29040@shareable.org>	<4A37B23F.6040604@eu.citrix.com>
	<20090616145421.GD29040@shareable.org>
	<4A37C82B.5030805@codemonkey.ws>
In-Reply-To: <4A37C82B.5030805@codemonkey.ws>
Content-Type: text/plain; charset="UTF-8"
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.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: Anthony Liguori <anthony@codemonkey.ws>
Cc: Christoph Hellwig <hch@lst.de>, qemu-devel <qemu-devel@nongnu.org>, Avi Kivity <avi@redhat.com>

Anthony Liguori wrote:

> Jamie Lokier wrote:
>>> Indeed.
>>> I have a patch that adds bdrv_set_read_only that set bs->read_only = 1
>>> so that bdrv_open2 can check if the flag is set and act accordingly.
>>> The problem is that in xen we read whether the device should be opened
>>> read only in the VM config file, I don't think the user can specify to
>>> open a drive read-only in qemu.
>>>     
>> What's missing is a "ro" sub-option to "-drive".
>>   
> 
> It only is useful if we can expose that read-only attribute to the 
> guest.  You can't do that consistently with all block devices so the 
> result would be that you'll fail write operations causing a guest to crash.
> 
> This is not friendly to a user who expects that ro would Just Work.
> 

Well, it could Just Work for cdrom.