Re: [Qemu-devel] migration: Introduce a new "--only-migratable" option

[Dr. David Alan Gilbert]

* Ashijeet Acharya (address@hidden) wrote:
> Hi Dave,
> 
> I have added the compatibility of this option for both command line
> and hotplug via qmp and hmp. Although, please confirm that making use
> of "device_add" is the only way of hotplugging devices into a QEMU
> instance.

Hmm; there's obsolete commands like usb_add and netdev_add as well.

> With this sorted out, there is one special case left where the device
> dynamically declares itself 'unmigratable' via migrate_add_blocker. I
> have a query regarding that which is, what is the preferred action in
> this scenario? Should I unmount the device or restrict the device from
> becoming unmigratable in the first place.
> For example, restrict 9pfs from mounting the filesystem (which you
> explained previously).
> 
> Or is there a completely different solution in your mind?

My preferred solution is to stop the device getting into the unmigratable
state; so whatever function tries to set it should fail (nicely) and
give an error - e.g the 9pfs should refuse to mount.  I'm not sure
how hard that is.

Dave

> Thanks
> Ashijeet
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK