Re: [Qemu-devel] [PATCH v3 0/5] Migration Deciphering aid

[Alexander Graf]

On 20.01.15 11:31, Amit Shah wrote:
> On (Fri) 26 Dec 2014 [15:42:43], Alexander Graf wrote:
>> Migration is a black hole to most people. One of the biggest reasons for
>> this is that its protocol is a secret, undocumented sauce of code rolling
>> around random parts of the QEMU code base.
>>
>> But what if we simply exposed the description of how the format looks like
>> alongside the actual migration stream? This is what this patch set does.
>>
>> It adds a new section that comes after the end of stream marker (so that it
>> doesn't slow down migration) that contains a JSON description of the device
>> state description.
>>
>> Along with this patch set also comes a python script that can read said JSON
>> from a migration dump and decipher the device state and ram contents of the
>> migration dump using it.
>>
>> With this, you can now fully examine all glorious details that go over the
>> wire when virtual machine state gets dumped, such as during live migration.
>>
>> We discussed the approach taken here during KVM Forum 2013. Originally, my 
>> idea
>> was to include a special device that contains the JSON data which can be 
>> enabled
>> on demand. Anthony suggested however to just always include the description 
>> data
>> after the end marker which I think is a great idea.
>>
>>   Example decoded migration: http://csgraf.de/mig/mig.txt
>>   Example migration description: http://csgraf.de/mig/mig.desc.txt
>>   Presentation: https://www.youtube.com/watch?v=iq1x40Qsrew
>>   Slides: https://www.dropbox.com/s/otp2pk2n3g087zp/Live%20Migration.pdf
> 
> Nice to finally see this!
> 
> I guess you have a v4 coming soon?

Yeah, I was just waiting on a bit more review :)


Alex