[Qemu-devel] Re: [PATCH v5 4/5] Inter-VM shared memory PCI device

[Cam Macdonell]

On Tue, May 11, 2010 at 11:05 AM, Anthony Liguori <address@hidden> wrote:
> On 05/11/2010 11:39 AM, Cam Macdonell wrote:
>>
>> Most of the people I hear from who are using my patch are using a peer
>> model to share data between applications (simulations, JVMs, etc).
>> But guest-to-host applications work as well of course.
>>
>> I think "transparent migration" can be achieved by making the
>> connected/disconnected state transparent to the application.
>>
>> When using the shared memory server, the server has to be setup anyway
>> on the new host and copying the memory region could be part of that as
>> well if the application needs the contents preserved.  I don't think
>> it has to be handled by the savevm/loadvm operations.  There's little
>> difference between naming one VM the master or letting the shared
>> memory server act like a master.
>>
>
> Except that to make it work with the shared memory server, you need the
> server to participate in the live migration protocol which is something I'd
> prefer to avoid at it introduces additional down time.

Fair enough, then to move to a resolution on this can we either

not support migration at this point, which leaves us free to add it
later as migration use cases become better understand. (my preference)

OR

1 - not support migration when the server is used
2 - if role=master is specified in the non-server case, then that
guest will copy the memory with it.  If role=peer is specified, the
guest will use the shared memory object on the destination host as is
(possibly creating it or output an error if memory object doesn't
exist).

Cam