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Date: Wed, 30 Mar 2011 18:50:11 +0200
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [Qemu-devel] CD-ROM bug round-up
Message-ID: <20110330165011.GF7766@redhat.com>
References: <AANLkTim_1kNJ6=13GpUXQBTbtjJUdAxL7=JXwCNq6W9G@mail.gmail.com>
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, Juan Quintela <quintela@redhat.com>, Markus Armbruster <armbru@redhat.com>, qemu-devel <qemu-devel@nongnu.org>, Ryan Harper <ryanh@us.ibm.com>, Amit Shah <amit.shah@redhat.com>

On Wed, Mar 30, 2011 at 05:40:40PM +0100, Stefan Hajnoczi wrote:
> Several of us have been investigating CD-ROM bugs.  Let's update each
> other, make sure we're not duplicating effort, and see if we can help
> each other make progress.
> 
> = Stefan =
> 
> Guests do not notice media change when using Linux host CD-ROM
> pass-through for two reasons:
> 1. QEMU is caching the device size for removable media and never updating it.
> 2. On Linux hosts the /dev/cdrom file descriptor needs to be reopened
> to refresh the underlying device size.
> 
> Patches have been posted to qemu-devel.
> 
> Libvirt does not recognize eject failure due to locked tray.  This
> causes libvirt to get out-of-sync and believe the medium was
> successfully changed.  A libvirt fix is in progress:
> https://bugzilla.redhat.com/show_bug.cgi?id=689101
> 
> = Anthony =
> 
> Using 'change' or scripted commands without a delay between closing
> the BlockDriverState and opening the new CD-ROM.  The guest does not
> have a chance to poll the drive and determine a medium present ->
> medium not present transition followed by a medium not present ->
> medium present transition.
> 
> A fix for this does not exist yet and might be tricky since we need to
> delay or wait for the guest to poll once before opening the new
> CD-ROM.
> 
This sounds familiar and should have been fixed by commit
93c8cfd9e67a62711b86f4c93747566885eb7928

> = Amit =
> 
> Found that 2.6.38 and later guest kernels fail to report media change.
>  The new in-kernel media change polling framework issues ATAPI
> commands which are not implemented in hw/ide/core.c.
> 
> = Juan =
> 
> ATA HSM violation errors after live migration while CD-ROM read
> operations.  This is probably a hw/ide/* or DMA migration bug.
> 
> = Markus =
> 
> ?
> 
> Stefan

--
			Gleb.