On Fri, Oct 05, 2018 at 11:38:14AM +0200, Andrea Bolognani wrote:
On Fri, 2018-10-05 at 09:54 +0100, Daniel P. Berrangé wrote:
On Fri, Oct 05, 2018 at 10:34:33AM +0200, Jiri Denemark wrote:
But what if QEMU (or any other hypervisor) marks something (device model, machine type) as deprecated and we use that deprecated value as our default. Shouldn't we be able to tell about it to our users (here runtime warnings could help) when they use such thing explicitly and choose a different default value? That would help users with the transition and once hypervisor drops support for it completely, fewer existing domains will be affected since the recently created ones would already use non-deprecated defaults.
QEMU already emits warnings on stderr whenever something that is deprecated is used, and those end up in the libvirt log file for that guest. I don't think that we need to duplicate what QEMU is already reporting again.
Warnings printed on stderr -> users and developers will actually see them, be annoyed by them, eventually cave in and act upon them.
Warnings written to a log -> nobody will notice them, until one day things suddenly stop working apparently out of the blue.
We might pretend that's not the case, but really, it is.
Unless you're talking about a CLI tool (virt-install, virsh), there is no difference between those two scenarios. For virt-manager, virt-viewer, oVirt, OpenStack, KubeVirt, stderr is never going to be seen, it just ends up in a log file. So I don't find that distinction to be compelling. 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 :|