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([2001:b07:6468:f312:d153:8d0f:94cf:5114]) by smtp.gmail.com with ESMTPSA id y68sm11178151wmd.39.2020.09.21.02.30.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 21 Sep 2020 02:30:16 -0700 (PDT) Subject: Re: [PATCH] PoC: Rust binding for QAPI (qemu-ga only, for now) To: Markus Armbruster , marcandre.lureau@redhat.com References: <20200910174850.716104-1-marcandre.lureau@redhat.com> <87mu1j8p7p.fsf@dusky.pond.sub.org> From: Paolo Bonzini Message-ID: <33bf618f-9c0d-b34f-cc55-35f4c35e8296@redhat.com> Date: Mon, 21 Sep 2020 11:30:15 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <87mu1j8p7p.fsf@dusky.pond.sub.org> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Received-SPF: pass client-ip=216.205.24.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/21 01:43:11 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -45 X-Spam_score: -4.6 X-Spam_bar: ---- X-Spam_report: (-4.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.501, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=-1, RCVD_IN_MSPIKE_WL=-0.01, 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: jsnow@redhat.com, stefanha@gmail.com, berrange@redhat.com, qemu-devel@nongnu.org, slp@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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. Paolo