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Re: [libvirt] [PATCH 0/2] qemu: Rework CD/DVD changing



On 17.05.2013 07:47, Li Wei wrote:
> Hi Michal, Daniel
> 
> It seems there is something wrong with the 2/2 part of this patchset.
> When I do an "change-media" command in virsh, it doesn't do any better
> than before, but even worse(I must to wait 5 secs to see the error).
> 
> I'm not family with libvirt, just add some log things in the qemu_hotplug.c
> and found the tray_status never change to open, but with michal's original
> patch (which do active poll on tray_status), I can do "change-media" successfully
> every time.

Yes & no. Thing is - originally we ignored tray status in the guest. So
in case guest has locked the tray and thus ignored our eject request, we
have changed the media anyway, resulting in possible I/O errors within
guest.

With my patch, we send eject request to the qemu, and actively poll for
the tray to open. We check for up to 10 times every 200ms. So guest has
2 seconds to open the tray. If the guest doesn't eject media and open
the tray we don't proceed with forcibly changing the media.

These patches are actually a bug fix for
https://bugzilla.redhat.com/show_bug.cgi?id=892289

> 
> IMHO, there must be some bug in the processing of qemu tray change.
> 
> Thanks,
> Wei
> 
> 
> On 01/25/2013 08:20 PM, Michal Privoznik wrote:
>> The first patch is bare bug fix (without any bug reported though).
>> The second is again a bug fix, but not so easy to spot. Basically, when we
>> change a media, we should issue 'eject' first, then wait until the tray gets
>> open, after which we can finally issue 'change' command. Even for bare 'eject'
>> we ought to check status, shouldn't we?
>>
>> Michal Privoznik (2):
>>   qemu_monitor: Fix tray-open attribute in query-block
>>   qemu_hotplug: Rework media changing process
>>
>>  src/qemu/qemu_hotplug.c      | 51 +++++++++++++++++++++++++++++++++++++++++---
>>  src/qemu/qemu_monitor_json.c |  2 +-
>>  src/qemu/qemu_monitor_text.c |  6 +++---
>>  3 files changed, 52 insertions(+), 7 deletions(-)
>>


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