Re: [Qemu-devel] [PATCH 1/3] scsi-disk: close drive on START_STOP

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 12/04/2013 08:33 PM, Markus Armbruster wrote:
> Paolo Bonzini <pbonzini@redhat.com> writes:
> 
>> Il 04/12/2013 05:55, Alexey Kardashevskiy ha scritto:
>>> Normally the user is expected to eject DVD if it is not locked by
>>> the guest. eject_device() makes few checks and calls bdrv_close()
>>> if DVD is not in use.
>>>
>>> However it is still possible to eject DVD even if it is in use.
>>> For that, QEMU sets "eject requested" flag, the guest reads it, issues
>>> ALLOW_MEDIUM_REMOVAL(enable=1) and START_STOP(start=0). But in this case,
>>> bdrv_close() is not called anywhere so it remains "inserted" in QEMU's
>>> terms.
>>
>> This is expected behavior, and matches what IDE does.
>>
>> Markus, can you confirm?
> 
> Confirmed.  See commit 4be9762.
> 
> Alexey, monitor commands eject does two things: it first opens the tray,
> and if that works, it removes the medium.
> 
> If the tray is locked closed, it tells the device model that eject was
> requested.  Works just like the physical eject button.
> 
> With -f, it then rips out the medium.  This is similar to opening the
> tray with a unbent paperclip.  Let's ignore this case.
> 
> The scsi-cd device model tells the guest about the eject request.  A
> well-behaved guest will then command the device to unlock and open the
> tray.
> 
> The guest uses the same commands on behalf of its applications,
> e.g. /usr/bin/eject.
> 
> Your patch changes behavior of "eject /dev/sr0 && eject -t /dev/sr0":
> you no longer get the same medium back.  You normally do with real
> hardware.
> 
> The somewhat unfortunate consequence is that monitor command eject can
> only remove the medium when the tray is not locked.


Oh. Wow. Nice :-/

Ok. So. It is expected that the real system will close the tray back if it
was mounted, is not it?

Right now, after "eject" "info block" is like this:

cd1: virtimg/Fedora-19-ppc64-netinst.iso (raw)
    Removable device: locked, tray open

And the mountpoint does not work in the guest. The state above even
persists after "umount" in the guest. It only becomes correct again
(tray==closed) when I mount DVD again.

Is it all expected to work like this? Thanks.


-- 
Alexey