Re: [Qemu-devel] [PATCH v1 1/1] qmp: marking qmp_cpu as deprecated

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

On Mon, Dec 18, 2017 at 09:55:55AM -0200, Daniel Henrique Barboza wrote:
> 
> 
> On 12/18/2017 08:59 AM, Daniel P. Berrange wrote:
> > On Mon, Dec 18, 2017 at 08:53:18AM -0200, Daniel Henrique Barboza wrote:
> > > qmp_cpu is a nop that was created a while ago in commit 755f196898
> > > ("qapi: Convert the cpu command") for the sake of compatibility,
> > > due to the existence of hmp_cpu.
> > > 
> > > Today, there is no need or requirement to keep it as is. QMP is
> > > meant to be as stateless as possible, thus any QMP command that
> > > needs a specific monitor CPU setup should provide it in its
> > > arguments, instead of relying in the current QMP monitor state.
> > > 
> > > This patch flags qmp_cpu as deprecated in qemu-doc.texi and changes
> > > qmp_cpu body to show a deprecation message if used.
> > > 
> > > Signed-off-by: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>
> > > ---
> > > Although I've changed the behavior of qmp_cpu to return an error
> > > instead of doing nothing, no errors were found in the Travis
> > > build of the patch. Code inspection confirms that qmp_cpu isn't
> > > being used in QEMU.
> > > 
> > > A quick inspection in Libvirt code shows that there is no reference
> > > to 'qmp_cpu' there either, but to be sure I've CCed Daniel here
> > > so he can comment/confirm if Libvirt does not care for this change.
> > > 
> > >   qemu-doc.texi | 6 ++++++
> > >   qmp.c         | 2 +-
> > >   2 files changed, 7 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/qemu-doc.texi b/qemu-doc.texi
> > > index f7317dfc66..2b63f9a325 100644
> > > --- a/qemu-doc.texi
> > > +++ b/qemu-doc.texi
> > > @@ -2516,6 +2516,12 @@ subsystem image.
> > >   The ``convert -s snapshot_id_or_name'' argument is obsoleted
> > >   by the ``convert -l snapshot_param'' argument instead.
> > > +@section System emulator machine protocol commands
> > > +
> > > +@subsection qmp_cpu (since 2.12.0)
> > > +
> > > +The ``qmp_cpu'' command is deprecated. Do not use this command.
> > Just saying it is deprecated doesn't add any useful info, rather
> > explain why it is deprecated & what (if anything) to use instead.
> > e.g.
> > 
> >    The ``qmp_cpu'' command is a functional no-op. There is no reason
> >    to invoke this command and it will be removed with no replacement.
> 
> Thanks, I'll add more info in qemu-doc.texi in the next version.
> 
> Also, just checked that I didn't touch qapi-schema.json. This is how
> it reads about qmp_cpu:
> 
> 
> # This command is a nop that is only provided for the purposes of
> compatibility.
> #
> # Since: 0.14.0
> #
> # Notes: Do not use this command.
> 
> Should we change it to mention that the command is deprecated, something
> like:
> 
> # Notes: Do not use this command - it is deprecated and will disappear in
> the future.
> 
> 
> Or just adding the deprecation note in qemu-doc.texi is enough?

Lets modify the QAPI file too, since you never know what users will read
first !

Regards,
Daniel
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