From: Igor Mammedov <imammedo@redhat.com>
To: Markus Armbruster <armbru@redhat.com>
Cc: "Thomas Huth" <thuth@redhat.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
libvir-list@redhat.com, QEMU <qemu-devel@nongnu.org>,
"Marc-André Lureau" <marcandre.lureau@gmail.com>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Richard Henderson" <rth@twiddle.net>
Subject: Re: [PATCH 2/2] Add -mem-shared option
Date: Tue, 10 Dec 2019 14:09:49 +0100 [thread overview]
Message-ID: <20191210140949.4a1c3ff2@redhat.com> (raw)
In-Reply-To: <87tv6831vr.fsf@dusky.pond.sub.org>
On Tue, 10 Dec 2019 11:34:32 +0100
Markus Armbruster <armbru@redhat.com> wrote:
> Eduardo Habkost <ehabkost@redhat.com> writes:
>
> > +Markus
> >
> > On Tue, Dec 03, 2019 at 03:43:03PM +0100, Igor Mammedov wrote:
> >> On Tue, 3 Dec 2019 09:56:15 +0100
> >> Thomas Huth <thuth@redhat.com> wrote:
> >>
> >> > On 02/12/2019 22.00, Eduardo Habkost wrote:
> >> > > On Mon, Dec 02, 2019 at 08:39:48AM +0100, Igor Mammedov wrote:
> >> > >> On Fri, 29 Nov 2019 18:46:12 +0100
> >> > >> Paolo Bonzini <pbonzini@redhat.com> wrote:
> >> > >>
> >> > >>> On 29/11/19 13:16, Igor Mammedov wrote:
> >> > >>>> As for "-m", I'd make it just an alias that translates
> >> > >>>> -m/mem-path/mem-prealloc
> >> > >>>
> >> > >>> I think we should just deprecate -mem-path/-mem-prealloc in 5.0. CCing
> >> > >>> Thomas as mister deprecation. :)
> >> > >>
> >> > >> I'll add that to my series
> >> > >
> >> > > Considering that the plan is to eventually reimplement those
> >> > > options as syntactic sugar for memory backend options (hopefully
> >> > > in less than 2 QEMU releases), what's the point of deprecating
> >> > > them?
> >> >
> >> > Well, it depends on the "classification" [1] of the parameter...
> >> >
> >> > Let's ask: What's the main purpose of the option?
> >> >
> >> > Is it easier to use than the "full" option, and thus likely to be used
> >> > by a lot of people who run QEMU directly from the CLI? In that case it
> >> > should stay as "convenience option" and not be deprecated.
> >> >
> >> > Or is the option merely there to give the upper layers like libvirt or
> >> > some few users and their scripts some more grace period to adapt their
> >> > code, but we all agree that the options are rather ugly and should
> >> > finally go away? Then it's rather a "legacy option" and the deprecation
> >> > process is the right way to go. Our QEMU interface is still way
> >> > overcrowded, we should try to keep it as clean as possible.
> >>
> >> After switching to memdev for main RAM, users could use relatively
> >> short global options
> >> -global memory-backend.prealloc|share=on
> >> and
> >> -global memory-backend-file.mem-path=X|prealloc|share=on
> >>
> >> instead of us adding and maintaining slightly shorter
> >> -mem-shared/-mem-path/-mem-prealloc
> >
> > Global properties are a convenient way to expose knobs through
> > the command line with little effort, but we have no documentation
> > on which QOM properties are really supposed to be touched by
> > users using -global.
> >
> > Unless we fix the lack of documentation, I'd prefer to have
> > syntactic sugar translated to -global instead of recommending
> > direct usage of -global.
>
> Fair point.
>
> I'd take QOM property documentation over still more sugar.
>
> Sometimes, the practical way to make simple things simple is sugar. I
> can accept that. This doesn't look like such a case, though.
I can document concrete globals as replacement at the place
-mem-path/-mem-prealloc are documented during deprecation and
then in 2 releases we will just drop legacy syntax and keep only
globals over there.
(eventually it will spread various globals
over man page, which I don't like but we probably should start
somwhere and consolidate later if globals in man page become
normal practice.)
next prev parent reply other threads:[~2019-12-10 13:10 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-28 14:15 [PATCH 0/2] RFC: add -mem-shared option Marc-André Lureau
2019-11-28 14:15 ` [PATCH 1/2] memfd: add qemu_memfd_open() Marc-André Lureau
2019-11-28 14:15 ` [PATCH 2/2] Add -mem-shared option Marc-André Lureau
2019-11-28 16:14 ` Eduardo Habkost
2019-11-28 16:28 ` Igor Mammedov
2019-11-28 20:31 ` Marc-André Lureau
2019-11-29 10:07 ` Igor Mammedov
2019-11-29 10:11 ` Paolo Bonzini
2019-11-29 12:01 ` Markus Armbruster
2019-11-29 20:31 ` Eduardo Habkost
2019-11-29 12:16 ` Igor Mammedov
2019-11-29 17:46 ` Paolo Bonzini
2019-12-02 7:39 ` Igor Mammedov
2019-12-02 21:00 ` Eduardo Habkost
2019-12-03 8:56 ` Thomas Huth
2019-12-03 14:43 ` Igor Mammedov
2019-12-09 20:58 ` Eduardo Habkost
2019-12-10 10:34 ` Markus Armbruster
2019-12-10 13:09 ` Igor Mammedov [this message]
2019-12-03 21:34 ` Eduardo Habkost
2019-11-28 16:10 ` [PATCH 0/2] RFC: add " Eduardo Habkost
2019-11-29 9:18 ` Igor Mammedov
2019-11-29 9:31 ` Paolo Bonzini
2019-11-29 10:23 ` Igor Mammedov
2019-11-29 11:21 ` Paolo Bonzini
2019-11-29 20:21 ` Eduardo Habkost
2019-12-01 15:40 ` Marc-André Lureau
2019-12-01 18:03 ` Paolo Bonzini
2019-11-28 16:59 ` Dr. David Alan Gilbert
2019-11-29 9:23 ` Igor Mammedov
2019-12-13 11:39 ` Stefan Hajnoczi
2019-12-13 13:12 ` Igor Mammedov
2019-11-29 4:37 ` no-reply
2019-11-29 5:34 ` no-reply
2019-11-29 7:02 ` Gerd Hoffmann
2019-11-29 7:30 ` Marc-André Lureau
2019-11-29 9:27 ` Daniel P. Berrangé
2019-11-29 9:31 ` Marc-André Lureau
2019-11-29 9:42 ` Daniel P. Berrangé
2019-11-29 9:45 ` Marc-André Lureau
2019-11-29 11:44 ` Gerd Hoffmann
2019-11-29 9:33 ` Paolo Bonzini
2019-11-29 9:39 ` Daniel P. Berrangé
2019-11-29 9:52 ` Paolo Bonzini
2019-11-29 10:13 ` Igor Mammedov
2019-11-29 11:20 ` Paolo Bonzini
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