Re: [Qemu-devel] [PATCH] vmstate: Add unmigratable flag

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2011-06-19 22:46, Cam Macdonell wrote:
> On Thu, Jun 9, 2011 at 2:39 PM, Jan Kiszka <jan.kiszka@web.de> wrote:
>> On 2011-06-09 22:00, Anthony Liguori wrote:
>>> On 06/09/2011 11:44 AM, Jan Kiszka wrote:
>>>> A first step towards getting rid of register_device_unmigratable
>>>> (ivshmem and lacking vmstate support in virtio are blocking this):
>>>>
>>>> Allow to register an unmigratable vmstate via qdev, i.e. tag a device
>>>> declaratively.
>>>
>>> I thought part of the problem with this was that for some devices (like
>>> ivshmem), whether it can be migrated was dynamic.  It depends on
>>> configuration, state, etc.
>>
>> That only applies to ivshmem (the other user is device assignment which
>> is unconditionally unmigratable). And the ivshmem issue could easily be
>> solved by defining two devices, ivshmem-peer (or just ivshmem) and
>> ivshmem-master, eliminating the need for the role property.
>>
>> I don't think there will ever be a use case for a "transformer" device
>> that becomes unmigratable during runtime (would be a nightmare for
>> management apps anyway).
>>
>> If breaking the user interface of ivshmem for this is OK, I'll post a patch.
>>
>> Jan
>>
>>
> 
> The migratability of ivshmem is not dynamic in that it doesn't change
> at runtime, it's set when the device is created, either role=peer or
> role=master is specified.  So iiuc, this could work with ivshmem.

So you are fine with breaking the interface? Everyone else as well? Then
I'll cook a patch to sort at least this out for 0.15.

Jan

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