On Mon, Dec 01, 2025 at 02:29:57PM +0000, David Woodhouse wrote: > On Mon, 2025-12-01 at 14:12 +0000, Daniel P. Berrangé wrote: > > From QEMU's POV, live migration and snapshots > > are indistiguishable operations, both using the same functionaility. > > > > eg > > $ qemu-system-x86_64 -monitor stdio -device vmclock > > (qemu) migrate file:snapshot.img > > > > and > > > > $ qemu-system-x86_64 -monitor stdio -device vmclock -incoming > > file:snapshot.img > > > > > > and we can't check the QEMU migration target being "file:" and mgmt > > apps can use the "fd:" protocol to pass in a pre-opened target which can > > be a socket or pipe or file. > > What triggers the vmgenid to actually get updated for a snapshot? > That's the condition we're after, isn't it?
I don't quiet understand the sequences, but libvirt is involved in setting guid=nnnn as an arg to -device vmgenid when it spawns QEMU. This means libvirt has control over when it is changed or not. With 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 :|
