Re: [PATCH v3 2/4] usb/hub: mark as deprecated

["Daniel P. Berrangé" <berrange@redhat.com>]

On Thu, Jun 13, 2024 at 12:38:31PM +0200, Markus Armbruster wrote:
> Daniel P. Berrangé <berrange@redhat.com> writes:
> 
> > On Thu, Jun 13, 2024 at 10:31:56AM +0200, Markus Armbruster wrote:
> >> Alex Bennée <alex.bennee@linaro.org> writes:
> >> 
> >> > Daniel P. Berrangé <berrange@redhat.com> writes:
> >> >
> >> >> On Thu, Jun 06, 2024 at 04:30:08PM +0200, Gerd Hoffmann wrote:
> >> >>> The hub supports only USB 1.1.  When running out of usb ports it is in
> >> >>> almost all cases the much better choice to add another usb host adapter
> >> >>> (or increase the number of root ports when using xhci) instead of using
> >> >>> the usb hub.
> >> >>
> >> >> Is that actually a strong enough reason to delete this device though ?
> >> >> This reads like its merely something we don't expect to be commonly
> >> >> used, rather than something we would actively want to delete.
> >> >
> >> > This does seem quite aggressive because there may be cases when users
> >> > explicitly want to use old devices. Maybe there is need for a third
> >> > state (better_alternatives?) so we can steer users away from old command
> >> > lines they may have picked up from the web to the modern alternative?
> >> 
> >> What exactly do we mean when we call something deprecated?
> >> 
> >> For me, it means "you should not normally use this".
> >> 
> >> Important special case: "because we intend to remove it."
> >
> > That's not the special case, it is the regular case - the documented
> > meaning of 'deprecated' in QEMU. When we deprecate something, it is
> > a warning that we intend to delete it in 2 releases time.
> 
> It's the regular case in QEMU today because we made it so there, by
> electing to limit deprecation to "because we intend to remove it."

Fair point, but assigning additional meanings to the existing 'deprecation'
concept will undermine the value QEMU & its consumers obtain from current
usage.

Consumers know if they see the "deprecated" marker, it has started a clock
ticking and they must immediately plan work to stop using the feature.

QEMU maintainers know if they see the 'deprecated' marker and it has been
2 releases, then we can delete it.

I don't want to loose that clear & easily understood meaning, by overloading
"deprecated" for scenarios like "it is sometimes better to use a different
device instead of this one, depending on factors X, Y & Z".

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 :|