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Tue, 18 Aug 2020 09:38:57 +0000 (UTC) Date: Tue, 18 Aug 2020 11:38:55 +0200 From: Cornelia Huck To: "Daniel P. =?UTF-8?B?QmVycmFuZ8Op?=" Subject: Re: device compatibility interface for live migration with assigned devices Message-ID: <20200818113855.647938c0.cohuck@redhat.com> In-Reply-To: <20200818092433.GD20215@redhat.com> References: <20200805075647.GB2177@nanopsycho> <20200805093338.GC30485@joy-OptiPlex-7040> <20200805105319.GF2177@nanopsycho> <20200810074631.GA29059@joy-OptiPlex-7040> <20200814051601.GD15344@joy-OptiPlex-7040> <20200818085527.GB20215@redhat.com> <20200818110617.05def37c.cohuck@redhat.com> <20200818092433.GD20215@redhat.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Received-SPF: none client-ip=205.139.110.61; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/18 02:16:14 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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=-1, SPF_HELO_NONE=0.001, SPF_NONE=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: kvm@vger.kernel.org, libvir-list@redhat.com, Jason Wang , qemu-devel@nongnu.org, kwankhede@nvidia.com, eauger@redhat.com, xin-ran.wang@intel.com, corbet@lwn.net, openstack-discuss@lists.openstack.org, shaohe.feng@intel.com, kevin.tian@intel.com, Yan Zhao , Parav Pandit , jian-feng.ding@intel.com, dgilbert@redhat.com, zhenyuw@linux.intel.com, hejie.xu@intel.com, bao.yumeng@zte.com.cn, Alex Williamson , smooney@redhat.com, intel-gvt-dev@lists.freedesktop.org, eskultet@redhat.com, Jiri Pirko , dinechin@redhat.com, devel@ovirt.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 18 Aug 2020 10:24:33 +0100 Daniel P. Berrang=C3=A9 wrote: > On Tue, Aug 18, 2020 at 11:06:17AM +0200, Cornelia Huck wrote: > > On Tue, 18 Aug 2020 09:55:27 +0100 > > Daniel P. Berrang=C3=A9 wrote: > > =20 > > > On Tue, Aug 18, 2020 at 11:24:30AM +0800, Jason Wang wrote: =20 > > > > Another point, as we discussed in another thread, it's really hard = to make > > > > sure the above API work for all types of devices and frameworks. So= having a > > > > vendor specific API looks much better. =20 > > >=20 > > > From the POV of userspace mgmt apps doing device compat checking / mi= gration, > > > we certainly do NOT want to use different vendor specific APIs. We wa= nt to > > > have an API that can be used / controlled in a standard manner across= vendors. =20 > >=20 > > As we certainly will need to have different things to check for > > different device types and vendor drivers, would it still be fine to > > have differing (say) attributes, as long as they are presented (and can > > be discovered) in a standardized way? =20 >=20 > Yes, the control API and algorithm to deal with the problem needs to > have standardization, but the data passed in/out of the APIs can vary. >=20 > Essentially the key is that vendors should be able to create devices > at the kernel, and those devices should "just work" with the existing > generic userspace migration / compat checking code, without needing > extra vendor specific logic to be added. >=20 > Note, I'm not saying that the userspace decisions would be perfectly > optimal based on generic code. They might be making a simplified > decision that while functionally safe, is not the ideal solution. > Adding vendor specific code might be able to optimize the userspace > decisions, but that should be considered just optimization, not a > core must have for any opertion. Yes, that sounds reasonable.