From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from [140.186.70.92] (port=34198 helo=eggs.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1Q7Nlv-0007g9-Hf
	for qemu-devel@nongnu.org; Wed, 06 Apr 2011 04:07:29 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <amit.shah@redhat.com>) id 1Q7Nlt-0000wI-CN
	for qemu-devel@nongnu.org; Wed, 06 Apr 2011 04:07:26 -0400
Received: from mx1.redhat.com ([209.132.183.28]:11066)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <amit.shah@redhat.com>) id 1Q7Nlt-0000v1-0r
	for qemu-devel@nongnu.org; Wed, 06 Apr 2011 04:07:25 -0400
Date: Wed, 6 Apr 2011 13:37:12 +0530
From: Amit Shah <amit.shah@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v2 3/3] raw-posix: Re-open host CD-ROM after
	media change
Message-ID: <20110406080712.GD20671@amit-x200.redhat.com>
References: <4D99C61E.3080600@redhat.com> <4D99C9ED.3020602@codemonkey.ws>
	<4D99CC74.9070703@redhat.com>
	<BANLkTimNCCFkRuPaJsmN6Q1ThV3-OP8MCA@mail.gmail.com>
	<20110405064120.GB2872@amit-x200.redhat.com>
	<4D9AC940.5000502@redhat.com>
	<20110405080900.GE2872@amit-x200.redhat.com>
	<4D9ADA36.8040306@redhat.com>
	<20110405091203.GC27661@amit-x200.redhat.com>
	<4D9ADE2A.2020201@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <4D9ADE2A.2020201@redhat.com>
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: Avi Kivity <avi@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>, Juan Quintela <quintela@redhat.com>, libvir-list@redhat.com, Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel@nongnu.org, Ryan Harper <ryanh@us.ibm.com>

On (Tue) 05 Apr 2011 [12:17:30], Avi Kivity wrote:
> >Guest kernel bug: CDROM change event missed, so the the revalidate
> >call isn't made, which causes stale data (like disc size) to be used
> >on newer media.
> >
> >qemu bug: We don't handle the GET_EVENT_STATUS_NOTIFICATION command
> >from guests (which is a mandatory command acc. to scsi spec) which the
> >guest uses to detect CDROM changes.  Once this command is implemented,
> >QEMU sends the required info the guest needs to detect CDROM changes.
> >I have this implemented locally (also sent as RFC PATCH 2/3 in the
> >'cdrom bug roundup' thread.
> >
> >So: even if qemu is updated to handle this command, the guest won't
> >work correctly since it misses the event.
> 
> Okay.  We aren't responsible for guest kernel bugs, especially those
> which apply to real hardware (we should make more effort for virtio
> bugs).  It's enough that we fix qemu here.

Actually I forgot about this already: it is possible for a workaround
in qemu: inject the event twice instead of once.  ie, if the spec says
'SENSE_UNIT_ATTENTION' needs to be reset if some cmd is successful,
don't reset it the first time.  That's how I confirmed the kernel bug
last week.  It is such a horrible hack that I didn't want to keep it
around at all :-)

		Amit