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Date: Tue, 05 Oct 2010 15:49:12 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: [Qemu-devel] Re: [RFC PATCH 0/5] Save state error handling (kill
	off no_migrate)
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To: Alex Williamson <alex.williamson@redhat.com>
Cc: cam@cs.ualberta.ca, qemu-devel@nongnu.org, quintela@redhat.com

On 10/05/2010 03:46 PM, Alex Williamson wrote:
> On Tue, 2010-10-05 at 15:41 -0500, Anthony Liguori wrote:
>    
>> On 10/05/2010 03:35 PM, Alex Williamson wrote:
>>      
>>> I was thinking of making KVM VMs with assigned PCI devices
>>> unsavable/unmigratable, but I wasn't thrilled with the
>>> no_migrate solutions.  The more generic solutions seems to be
>>> simply letting save handlers return an error if the device can't
>>> be migrated.  This is also much more generic than a one-way
>>> bit flip of the no_migrate flag.  For a vmsd based registration,
>>> the pre_save() routine seems to be the right place to allow
>>> devices to abort.  The series also carries the error back through
>>> all the vmstate callers.  If this looks good, I'll give it some
>>> more testing and submit as non-RFC.  Thanks,
>>>
>>>        
>> Doesn't this mean that we don't fail the migration until after
>> transferring all of the memory contents?
>>      
> That's the case with the current no_migrate implementation too, it
> doesn't get called until qemu_savevm_state_complete().  Thanks,
>    

Ouch, that's unfortunate but also should be easily fixable.

But making a save handler fail seems would make it impossible to get 
instant failure semantics.

Regards,

Anthony Liguori

> Alex
>
>
>