From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([140.186.70.92]:53955)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1QRly3-0008Mi-7k
	for qemu-devel@nongnu.org; Wed, 01 Jun 2011 10:00:20 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1QRlxx-00052k-HS
	for qemu-devel@nongnu.org; Wed, 01 Jun 2011 10:00:14 -0400
Received: from mx1.redhat.com ([209.132.183.28]:28358)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1QRlxx-000520-0U
	for qemu-devel@nongnu.org; Wed, 01 Jun 2011 10:00:09 -0400
Message-ID: <4DE64690.8020500@redhat.com>
Date: Wed, 01 Jun 2011 16:02:56 +0200
From: Kevin Wolf <kwolf@redhat.com>
MIME-Version: 1.0
References: <1305808412-16994-1-git-send-email-kwolf@redhat.com>	<1305808412-16994-6-git-send-email-kwolf@redhat.com>	<20110526181208.46aba2ae@doriath>
	<20110601104456.5469329b@doriath>
In-Reply-To: <20110601104456.5469329b@doriath>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH 05/18] ide: Turn debug messages into
	assertions
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: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel@nongnu.org

Am 01.06.2011 15:44, schrieb Luiz Capitulino:
> On Thu, 26 May 2011 18:12:08 -0300
> Luiz Capitulino <lcapitulino@redhat.com> wrote:
> 
>> On Thu, 19 May 2011 14:33:19 +0200
>> Kevin Wolf <kwolf@redhat.com> wrote:
>>
>>> These printfs aren't really debug messages, but clearly indicate a bug if they
>>> ever become effective.
>>
>> Then we have a bug somewhere, starting a VM with:
>>
>>  # qemu -hda disks/test.img -enable-kvm -m 1G -cdrom /dev/sr0
>>
>> Where the host's CDROM is empty, triggers one of these asserts:
>>
>>  qmp-unstable/hw/ide/pci.c:299: bmdma_cmd_writeb: Assertion `bm->bus->dma->aiocb == ((void *)0)'
> 
> I found out why this is happening. I'm passing '-snapshot' to the command-line,
> sorry for not mentioning it (I forgot I was using my devel alias).

And suddenly it's reproducible. :-)

I'll have a look.

> I also found out that /usr/bin/eject in the guest won't work when
> -snapshot is used. Shouldn't qemu ignore this flag when using cdrom
> passthrough?

"Won't work" means that it works like with a CD-ROM image? That would be
what I expect, as you end up having a qcow2 image with -snapshot.

Not sure what's the best way of fixing this. Maybe just ignoring
-snapshot for read-only block devices? Or we could try and forward the
eject request to the backing file if the format driver doesn't handle it.

Kevin