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Tue, 22 Sep 2020 16:59:56 +0200 (CEST) From: Markus Armbruster To: Paolo Bonzini Subject: Re: [PATCH] PoC: Rust binding for QAPI (qemu-ga only, for now) References: <20200910174850.716104-1-marcandre.lureau@redhat.com> <87mu1j8p7p.fsf@dusky.pond.sub.org> <33bf618f-9c0d-b34f-cc55-35f4c35e8296@redhat.com> Date: Tue, 22 Sep 2020 16:59:56 +0200 In-Reply-To: <33bf618f-9c0d-b34f-cc55-35f4c35e8296@redhat.com> (Paolo Bonzini's message of "Mon, 21 Sep 2020 11:30:15 +0200") Message-ID: <87blhxluvn.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Received-SPF: pass client-ip=63.128.21.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/22 02:07:04 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.455, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no 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: berrange@redhat.com, slp@redhat.com, stefanha@gmail.com, qemu-devel@nongnu.org, marcandre.lureau@redhat.com, jsnow@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Paolo Bonzini writes: > On 21/09/20 11:16, Markus Armbruster wrote: >> QMP is an *external* interface. >> >> It supports compatible evolution: we can make certain kinds of changes >> without affecting clients. These include: >> >> * Adding optional arguments >> >> * Adding results >> >> * Adding values to an enumeration type, branches to a union or >> alternate >> >> * Reordering members of enumerations, structs, unions >> >> * Turning an argument type into an alternate with the old type as branch >> >> We've made use of this extensively. See also >> docs/devel/qapi-code-gen.txt section "Compatibility considerations." >> >> How do such changes affect clients of the proposed D-Bus interface? > > All this makes me think that Q{MP,OM,API} badly needs rationale > documentation. docs/devel/qapi-code-gen.txt is fairly thorough (>8000 words), but it doesn't try to serve as rationale documentation.