Re: [Xen-devel] [PATCHv1 0/5] tools: rework VM Generation ID

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 21/05/14 17:07, Ian Campbell wrote:
> On Wed, 2014-05-21 at 14:21 +0100, David Vrabel wrote:
>> This series reworks the VM Generation ID to a) conform to the
>> published spec from Microsoft; b) simplify the save/restore code; and
>> c) extend the libxl API to allow toolstacks to use this feature.
>>
>> The VM Generation ID must be regenerated with a new random ID after
>> certain VM operations. For xl, a new ID is required when restoring
>> from a saved image (but not after a migration, reboot, pause/unpause).
> 
> Does reboot include shutdown and recreate? i.e. if I do
>  xl shutdown domain
>  xl create domain.cfg
> 
> what should happen?

It may use the same ID.

> If we have to preserve then that is going to be problematic for xl,
> since:
>  xl create domain.cfg

ID = A

>  xl save domain saved
>  xl restore saved # now the genid has changed

ID = B

>  xl shutdown domain
>  xl cr domain.cfg

ID = B

> has nowhere to store the new genid, even if domain.cfg were to contain
> the original one.

Yes.

I think I might just get xl to generate a new ID on every domain create
and restore/migrate.  This will give the correct behaviour where it
matter, even if it is sub-optimal.

I doubt anyone is running a Windows 2012 domain controller with xl anyway.

David


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