On Mon, Apr 19, 2021 at 06:15:56PM +0100, Daniel P. Berrangé wrote: > On Mon, Apr 19, 2021 at 06:11:47PM +0100, Dr. David Alan Gilbert wrote: > > * Eduardo Habkost (ehabk...@redhat.com) wrote: > > > I would make live migration policy an enum, just to make sure > > > we are explicit about the requirements: > > > > > > - UNKNOWN: this is the current state in QEMU 6.0, where we don't > > > really know what the user expects. > > > This can be the default on existing versioned machine types, > > > just for compatibility. > > > I suggest making this print warnings for every migration > > > blocker (like this patch does). > > > I suggest deprecating this behavior as soon as we can. > > > > > > - PREFERRED: try to make the VM migratable when possible, but > > > don't print a warning or error out if migration is blocked. > > > This seems to be the behavior expected by libvirt today. > > > > > > - NOT_NEEDED: live migration is not needed, and QEMU is free to > > > enable features that block live migration or change guest ABI. > > > We can probably make this the default on machine types that > > > never supported live migration. > > > > I suggest you could do this by adding: > > -warn-none-migratable > > -no-warn-none-migratable > > > > and then argue about defaults another time. > > If we're going to add new args, lets at least future proof our > approach with an extensible option that we can wire into QMP > too later > > -migratable none|preferred|required > > and letting us add extra key/value pairs to tune it if desired.
Having said that, we potentially don't need a dedicated arg if we just make 'migratable=none|preferred|required' be a property of the machine type and hook everything off that > > > > - REQUIRED: live migration is required, and adding a migration > > > blocker would be a fatal error. > > > This is already implemented by --only-migratable. > > > I suggest making this the default on versioned machine types > > > after a few releases, and after deprecating UNKNOWN. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
