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Date: Wed, 30 Sep 2009 21:04:50 +0200
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 3/4] SCSI-Hotdel: Implement drive_hot_del
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To: Wolfgang Mauerer <wolfgang.mauerer@siemens.com>
Cc: "Kiszka, Jan" <jan.kiszka@siemens.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, "wlm.libvirt@googlemail.com" <wlm.libvirt@googlemail.com>

On 09/30/09 17:45, Wolfgang Mauerer wrote:
> Gerd Hoffmann wrote:
>>     Hi,
>>
>>> +     dinfo = drive_get(type, bus, unit);
>>> +     if (!dinfo) {
>>> +         monitor_printf(mon, "Trying to remove non-existent device\n");
>>> +	 return;
>>> +     }
>>
>> No.  Just don't do this silly if/bus/unit parsing.  At very minimum use
>> drive_get_by_id() here, then have something like 'drive_del $id'.
>>
>> IMHO much better would be to go qdev instead though.  We should have
>> generic device_add + device_del monitor commands which work for any
>> device, pretty much like the -device command line switch.
>
> That makes sense, but I'd nevertheless prefer to stick with the
> more traditional approach right now, replacing the
> bus/unit parsing with an ID-based variant.

Have a look at the "qdev: bus management updates." patch series posted a 
few days ago.  It adds device_add+device_del.

> However, is there any
> standard way to get from an instance of DriveInfo to
> the corresponding instance of SCSIDevice respectively
> SCSIDeviceInfo?

No.  It is linked the other way around: The device has a reference to 
the DriveInfo.  Which is one of the reasons why I think drive_del isn't 
that a great idea.

cheers,
   Gerd