Re: [Qemu-devel] [PATCH 7/8] pseries: savevm support for PAPR virtual SCSI

[Paolo Bonzini]

Il 31/05/2013 12:12, Alexey Kardashevskiy ha scritto:
> On 05/31/2013 06:18 PM, Paolo Bonzini wrote:
>> Il 31/05/2013 07:58, Alexey Kardashevskiy ha scritto:
>>> On 05/27/2013 05:03 PM, Paolo Bonzini wrote:
>>>> Il 27/05/2013 08:48, Alexey Kardashevskiy ha scritto:
>>>>>>>
>>>>>>> This is only true when the rerror and werror options have the values
>>>>>>> "ignore" or "report".  See virtio-scsi for an example of how to save the
>>>>>>> requests using the save_request and load_request callbacks in 
>>>>>>> SCSIBusInfo.
>>>>>
>>>>> Sigh.
>>>>
>>>> ?
>>>
>>> I thought the series is ready to go but I was wrong. Furthermore when I got
>>> to the point where I could actually test the save/restore for vscsi_req,
>>> migration was totally broken on PPC and it took some time to fix it :-/
>>
>> It is ready.  I was just pointing out that it's not _production_ ready.
> 
> What is the difference then? :)

It is mergeable, but it needs further work and you should be aware of that.

>>> How do you trigger the situation when there are inactive requests which
>>> have to be migrated?
>>
>> You need to trigger an error.  For example, you could use a sparse image
>> on an almost-full partition and let "dd" fill your disk.  Then migrate
>> to another instance of QEMU on the same machine, the destination machine
>> should succeed migration but fail starting the machine.
> 
> Why would it fail? I run "dd", it fills the disk and stops.

You have to make it fill the _host_ disk before it fills the guest disk.
 That's why I mentioned a sparse image.

Then the machine pauses with the failing request in its queue.  When you
migrate, the request is migrated as well.

Paolo