Re: [Qemu-devel] Live migrate, inconsistent machine types - new machine type to fix?

[Alex Bligh]

Paolo,

On 21 Jul 2014, at 15:11, Paolo Bonzini <address@hidden> wrote:

> Il 21/07/2014 15:59, Alex Bligh ha scritto:
>>>>>> My guess is they will take a non-intrusive SRU which provides the
>>>>>> ability for live migrates to work. However, if not we will just
>>>>>> maintain it out of tree (like we were doing for various other
>>>>>> qemu bits).
>>>> 
>>>> Quite frankly: good luck.
>> Your best wishes are appreciated :-)
> 
> Good luck was referring to Ubuntu fixing it
> 
> Maintaining out of tree for you should not be hard indeed.
> 
> Please test reboot after migration.  It broke for us, and we couldn't
> upstream the patches exactly because it depended on the source version
> and not on the machine type.

Actually for me (and possibly for others) reboot isn't an issue,
because we'd be quite content if on reboot the machine type was
changed to pc-1.0 or perhaps even the current type (despite
the fact this probably gives Windows its normal apoplectic
licensing fit).

The reason is because in our environment (and possibly others)
the VMs are run by a large number of end customers who don't
want to have to reboot their machines exactly when our customer
(that runs the host) upgrades their host; hence live migrate
is essential. But saying "we've upgraded stuff and hence
your virtual hardware will change slightly when the machine
next reboots" is acceptable; indeed it's desirable given we
want to minimise the number of virtual hardware configurations
running. Then in 2 years when we have to deal with a 14.04->16.04
upgrade, we only need worry about one source migration type
(assuming the machines are rebooted at least once every two years).

But yes I will test it anyway.

-- 
Alex Bligh