Re: [PATCH 0/3] target: RFC: display deprecation note for '-cpu help'

[Cornelia Huck <cohuck@redhat.com>]

On Mon, Jul 18 2022, Daniel P. Berrangé <berrange@redhat.com> wrote:

> On Mon, Jul 18, 2022 at 11:37:35AM +0200, Cornelia Huck wrote:
>> Is it easy enough the figure out the deprecation note? I think you
>> either have to actually start something with the deprecated entity, or
>> use qmp (which is not that straightforward)?
>
> QMP doesn't tell you the note, just a boolean deprecation flag. It is
> only printed on startup only right now.
>
> In the context of libvirt what happens is that libvirt can report that
> something is deprecated (based on the QMP response). If you go ahead
> and use it anyway, you'll get the deprecation message in the logfile
> for the VM, and the VM gets marked tainted by libvirt, which serves
> as a guide to look in the logfile.

Hm... so, a user who notes via -help that 'foo' is deprecated does not
really have a good way to figure out what they should use instead, other
than actually trying to use 'foo'? Is that a use case worth spending
some effort on, or do we consider it more of a niche case?