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Fri, 15 May 2020 05:51:28 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 528BB11358BC; Fri, 15 May 2020 07:51:27 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Subject: Re: proposal: deprecate -readconfig/-writeconfig References: <7599153e-89a2-9a86-16ad-4a3c6a107b18@redhat.com> <20200514085622.GB1280939@redhat.com> <56379563-c1f3-3270-f9ac-5bdd49b324aa@redhat.com> <20200514153456.GL1280939@redhat.com> Date: Fri, 15 May 2020 07:51:27 +0200 In-Reply-To: <20200514153456.GL1280939@redhat.com> ("Daniel P. =?utf-8?Q?B?= =?utf-8?Q?errang=C3=A9=22's?= message of "Thu, 14 May 2020 16:34:56 +0100") Message-ID: <87blmpsq3k.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=205.139.110.120; envelope-from=armbru@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/14 23:27:07 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] 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_H2=-0.001, SPF_PASS=-0.001 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: Peter Maydell , John Snow , qemu-devel , Markus Armbruster , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Daniel P. Berrang=C3=A9 writes: > On Thu, May 14, 2020 at 10:40:40AM -0400, John Snow wrote: >>=20 >>=20 >> On 5/14/20 4:56 AM, Daniel P. Berrang=C3=A9 wrote: >> > On Thu, May 14, 2020 at 10:09:21AM +0200, Paolo Bonzini wrote: >> >> IMHO configuration files are in general a failed experiment. In >> >> practice, they do not add much value over just a shell script because >> >> they don't allow configuring all QEMU options, they are very much fix= ed >> >> (by their nature). I think it's more or less agreed that they are no= t >> >> solving any problem for higher-level management stacks as well; those >> >> would prefer to configure the VM via QMP or another API. >> >> >> >> So, any objections to deprecating -readconfig and -writeconfig? >> >=20 >> > Libvirt would like to have a config file for QEMU, but it would have >> > to be one that actually covers all the config options QEMU supports, >> > and ideally using a data format in common with that used for runtime >> > changes. So for libvirt's needs the current readconfig is entirely >> > useless. >> >=20 >>=20 >> Yeah. In this sense, would a json/yaml config file help, under the >> premise that you could just cat it into the pipe to configure a machine? >>=20 >> (Assuming we had proper runtime configuration commands, of course.) > > Yeah, the key thing is that you really want to be able to provide the > whole initial config in one go as an atomic action. I don't want to > issue 100 individual QMP commands to load each initial device. With > that in mind it doesn't really matter whether you do > > $ qemu -qmp stdio > (qmp) load-config /some/file.yaml > > vs > > $ qemu -qmp stdio -load-config /some/file.yaml > > though the latter is probably slightly nicer as it lets you grep > for the VM based on the filename visible in the CLI.=20 Once QEMU can do the former, providing the latter should be trivial. Not providing it would be unadvisable. Yes, a management application that talks QMP anyway can be expected to be quite happy with having to do initial configuration via QMP, with or without a load-config command. But human users won't be happy. Having to use a wrapper program to feed their configuration file to QMP adds undue complexity. [...]