Re: [Qemu-devel] [PATCH 03/17] iotests: ask qemu for supported formats

[Paolo Bonzini <pbonzini@redhat.com>]

On 07/06/2018 13:10, Thomas Huth wrote:
> On 07.06.2018 13:07, Paolo Bonzini wrote:
>> On 07/06/2018 09:50, Thomas Huth wrote:
>>>
>>>> There's no real need to kill off '?', unless it gets in the way of
>>>> steering people towards 'help'.  We should steer them toward 'help',
>>>> because '?' is a trap for insufficiently sophisticated users of
>>>> shell[*].
>>> ... and I agree with your points here.
>>>
>>> => I think we need a second list of deprecated feature (maybe we should
>>> call them "legacy features" instead of "deprecated"?), i.e. a list of
>>> features which we don't recommend for new code / scripts anymore, but
>>> which we do not intend to remove via our official deprecation policy any
>>> time soon. Things like "--enable-kvm" / "-no-kvm" or maybe even "-net"
>>> go into the same category.
>>
>> Yes, "-net" definitely goes there.
>>
>>> If you agree, I can try to come up with a patch (should the list go into
>>> qemu-doc.texi or a separate document in the the documentation folder?).
>>
>> I think it should go in docs/devel.
> 
> I currently rather tend to put it into a new appendix in qemu-doc.texi,
> since this is useful information for the normal users, too. Or how shall
> we communicate this to the users that the old options that they are used
> to are still there, but should not be used for new scripts anymore?

I think we should tell them directly in the text for things like "-net".
 The new document would put things together and be mostly about
command-line (anti)patterns.

As to "-enable-kvm", I don't see anything wrong with users using it, or
even with occasionally adding more options like it.  However, we should
warn developers that such simple options should be syntactic sugar for a
structured (i.e. QemuOpts-based) option like "-accel", and that it
should only be done for similarity with existing options.  Basically the
same reason why new options have both "?" and "help", even though "?" is
disliked.

Paolo