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bh=fUz3VuJoR/h5+pbpPOIhGlLeOogIr74x+lItSVqVr98=; b=XFz7I2PHJ9pe9mmWW1eFb3VeO6xdu0eiBEaRbAbV3dFSG45q4ZDQBiXMUkZU/ARCy2AGLl IW7hnlNhFn858K6HYc4zmwzCMy+5LYrStvpaf1jO2NudTtN1DOiaA7lLhWQWjaXLngAd/7 X3i9S9jkYxCY3Q0X3X2tBUozgFbj7m0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-9-JVWTWtWWNLaEPrcz3bvMKQ-1; Wed, 03 Jun 2020 09:34:05 -0400 X-MC-Unique: JVWTWtWWNLaEPrcz3bvMKQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8B27AEC1A3; Wed, 3 Jun 2020 13:34:04 +0000 (UTC) Received: from work-vm (ovpn-115-9.ams2.redhat.com [10.36.115.9]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C9BA211CC03; Wed, 3 Jun 2020 13:33:56 +0000 (UTC) Date: Wed, 3 Jun 2020 14:33:54 +0100 From: "Dr. David Alan Gilbert" To: David Hildenbrand Subject: Re: [PULL 04/12] hmp: Simplify qom-set Message-ID: <20200603133354.GF2974@work-vm> References: <87pnai7ymz.fsf@dusky.pond.sub.org> <20200602092601.GD2758@work-vm> <847cb8b5-1507-46cf-495a-952d41a3c2b2@redhat.com> <20200603104306.GC2974@work-vm> <457c1ac7-3281-5e98-481b-34d44e5174de@redhat.com> <20200603114317.GD2974@work-vm> <728b8cf4-7574-776c-c7fe-3ed5e20b33d2@redhat.com> <20200603122413.GE2974@work-vm> <8c6b3fae-a74c-effa-2d38-5e8cd4c72066@redhat.com> MIME-Version: 1.0 In-Reply-To: <8c6b3fae-a74c-effa-2d38-5e8cd4c72066@redhat.com> User-Agent: Mutt/1.13.4 (2020-02-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.81; envelope-from=dgilbert@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/03 01:12:11 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, T_HK_NAME_DR=0.01 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mszeredi@redhat.com, lukasstraub2@web.de, quintela@redhat.com, qemu-devel@nongnu.org, pannengyuan@huawei.com, f4bug@amsat.org, Markus Armbruster , stefanha@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * David Hildenbrand (david@redhat.com) wrote: > On 03.06.20 14:26, David Hildenbrand wrote: > > On 03.06.20 14:24, Dr. David Alan Gilbert wrote: > >> * David Hildenbrand (david@redhat.com) wrote: > >>> On 03.06.20 13:43, Dr. David Alan Gilbert wrote: > >>>> * David Hildenbrand (david@redhat.com) wrote: > >>>>> On 03.06.20 12:43, Dr. David Alan Gilbert wrote: > >>>>>> * David Hildenbrand (david@redhat.com) wrote: > >>>>>>> On 02.06.20 11:26, Dr. David Alan Gilbert wrote: > >>>>>>>> * Markus Armbruster (armbru@redhat.com) wrote: > >>>>>>>>> "Dr. David Alan Gilbert (git)" writes: > >>>>>>>>> > >>>>>>>>>> From: "Dr. David Alan Gilbert" > >>>>>>>>>> > >>>>>>>>>> Simplify qom_set by making it use qmp_qom_set and the JSON parser. > >>>>>>>>>> > >>>>>>>>>> (qemu) qom-get /machine smm > >>>>>>>>>> "auto" > >>>>>>>>>> (qemu) qom-set /machine smm "auto" > >>>>>>>>>> > >>>>>>>>>> Signed-off-by: Dr. David Alan Gilbert > >>>>>>>>>> Message-Id: <20200520151108.160598-3-dgilbert@redhat.com> > >>>>>>>>>> Reviewed-by: Philippe Mathieu-Daudé > >>>>>>>>>> Reviewed-by: Markus Armbruster > >>>>>>>>>> Signed-off-by: Dr. David Alan Gilbert > >>>>>>>>>> With 's'->'S' type change suggested by Paolo and Markus > >>>>>>>>> > >>>>>>>>> This is actually more than just simplification, it's disarming a bear > >>>>>>>>> trap: the string visitor is restricted to a subset of the QAPI types, > >>>>>>>>> and when you qom-set a property with a type it can't handle, QEMU > >>>>>>>>> aborts. I mentioned this in the discussion of possible ways out of the > >>>>>>>>> qom-get impasse, but missed reraising it in patch review. > >>>>>>>>> > >>>>>>>>> A suitably amended commit would be nice, but respinning the PR just for > >>>>>>>>> that may not be worthwhile. > >>>>>>>> > >>>>>>>> A bit late; still as long as we're removing bear traps not adding them. > >>>>>>> > >>>>>>> This breaks qom-set for my (virtio-mem) use case: > >>>>>>> > >>>>>>> echo "qom-set vm0 requested-size 300M" | sudo nc -U /var/tmp/mon_src > >>>>>>> QEMU 5.0.50 monitor - type 'help' for more information > >>>>>>> (qemu) qom-set vm0 requested-size 300M > >>>>>>> Error: Expecting at most one JSON value > >>>>>> > >>>>>> Does qom-set vm0 requested-size 300e6 do the same thing? > >>>>> > >>>>> The property is defined to be of type "size". > >>>>> > >>>>> (qemu) qom-set vm0 requested-size 300e6 > >>>>> Error: Parameter 'requested-size' expects uint64 > >>>>> > >>>>> (not sure how "size" and "uint64" are mapped here) > >>>> > >>>> I think the problem here is that the JSON parser is converting anything > >>>> with an 'e' as a float; JSON itself doesn't have the distinction > >>>> between int and float. > >>>> > >>> > >>> (and just to clarify - I assume you are aware - 300e6 != 300M. So the > >>> interface becomes way harder to use in case one wants to specify > >>> properly aligned sizes - 300M vs 314572800) > >> > >> Oops, yes, good point. > >> > >> I think on balance it's probably best that this keeps supporting JSON; > >> although tbh I'm not convinced there are any complex types that can be > >> set. > >> I'm not seeing a prettier answer. > > > > So, I have to use a calculator from now on to set a property that I can > > set on the QEMU cmdline just fine without it? :( > > > > This feels like a step backwards, @Markus any way to keep supporting sizes? > > Or what about adding qom-set-json instead for complex types instead of > changing the behavior if an existing interface? Yes, this isn't nice - we could add a flag to qom-set to take nice numerics. Dave > -- > Thanks, > > David / dhildenb -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK