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Fri, 15 May 2020 05:54:28 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 8E77B11358BC; Fri, 15 May 2020 07:54:27 +0200 (CEST) From: Markus Armbruster To: Paolo Bonzini Subject: Re: proposal: deprecate -readconfig/-writeconfig References: <7599153e-89a2-9a86-16ad-4a3c6a107b18@redhat.com> <20200514085622.GB1280939@redhat.com> <1287b3b8-9fd0-04d5-1dd2-66b695dace5d@redhat.com> Date: Fri, 15 May 2020 07:54:27 +0200 In-Reply-To: <1287b3b8-9fd0-04d5-1dd2-66b695dace5d@redhat.com> (Paolo Bonzini's message of "Thu, 14 May 2020 14:37:34 +0200") Message-ID: <877dxdspyk.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 10.5.11.13 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=207.211.31.120; envelope-from=armbru@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/14 22:56:02 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_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: John Snow , Peter Maydell , "Daniel P. =?utf-8?Q?Berrang=C3=A9?=" , qemu-devel Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Paolo Bonzini writes: > On 14/05/20 10:56, 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 fixed >>> (by their nature). I think it's more or less agreed that they are not >>> 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. > > Yes, this is what I was thinking about. > >> For a less general purpose mgmt app, that targets some specific use >> cases I could imagine people might have used readconfig. [...] >> If we deprecate them, the only alternative users have right now is >> to go back to passing CLI args. [...] We'd be deciding to kill the >> feature with no direct replacement, even though it is potentially >> useful in some limited scenarios. >>=20 >> If we have a general strategy to eliminate QemuOpts and move entirely >> to QAPI based config, then I can see -readcofig/-writeconfig may be >> creating a burden of back compatibility on maintainers. > > I don't see QemuOpts going away anytime soon, but I do see more QMP/QAPI > and less command line in the future as far as management tools are > concerned. QemuOpts and HMP will remain for direct usage, for the > foreseeable future. I'd prefer not to have two separate configuration infrastructures. > So I guess we can keep -readconfig but deprecate, or even remove, > -writeconfig. Deprecate both as stable interfaces, remove neither.