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bh=YV1EJ29Z2VxIqaQGAYvHH+VrWl0xURqFQHwSZpWNUKs=; b=eH/fdHOo3fQPxr5U8ayY/H5SQbNhMJFJN4DvwM252zA9z016Pn4PE+bvOA9cMuMHIMeZ20 BiZu5Y+zyaH11vu9U/7yfQfOkFW07I2dl+Wh/3MIgX/J4PGmg9yPjKXRD3d/OAbPUPjMSM bY7J2wd+xOlLo9kl0cRy3TS12sxeP44= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-262-unmLua_kP8iW7YqsqbyktQ-1; Wed, 27 Jan 2021 12:56:51 -0500 X-MC-Unique: unmLua_kP8iW7YqsqbyktQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 43ECA8066F7; Wed, 27 Jan 2021 17:56:50 +0000 (UTC) Received: from redhat.com (ovpn-115-120.ams2.redhat.com [10.36.115.120]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A8BFF1F474; Wed, 27 Jan 2021 17:56:48 +0000 (UTC) Date: Wed, 27 Jan 2021 17:56:45 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Igor Mammedov Subject: Re: [PATCH v3] machine: add missing doc for memory-backend option Message-ID: <20210127175645.GW3653144@redhat.com> References: <20210121161504.1007247-1-imammedo@redhat.com> <20210127104511.GF3653144@redhat.com> <20210127105436.GG3653144@redhat.com> <756c025a-3811-4a36-98a2-3a02bd756523@redhat.com> <20210127163522.5a8db09a@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210127163522.5a8db09a@redhat.com> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.308, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Michal Privoznik , pkrempa@redhat.com, qemu-devel@nongnu.org, pbonzini@redhat.com, peter.maydell@linaro.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jan 27, 2021 at 04:35:22PM +0100, Igor Mammedov wrote: > On Wed, 27 Jan 2021 15:24:26 +0100 > Michal Privoznik wrote: > > > On 1/27/21 11:54 AM, Daniel P. Berrangé wrote: > > > On Wed, Jan 27, 2021 at 10:45:11AM +0000, Daniel P. Berrangé wrote: > > >> On Thu, Jan 21, 2021 at 11:15:04AM -0500, Igor Mammedov wrote: > > > > > > >> > > >> How does a mgmt app know which machine types need to use this > > >> option ? The machine type names are opaque strings, and apps > > >> must not attempt to parse or interpret the version number > > >> inside the machine type name, as they can be changed by > > >> distros. IOW, saying to use it for machine types 4.0 and > > >> older isn't a valid usage strategy IMHO. > it's possible (but no necessary) to use knob with new machine types > (defaults for these match suggested property value). IIUC, this means that setting the property has no impact on migration ABI for new machine types > 4.0.... > Limiting knob usage to 4.0 and older would allow us to drop > without extra efforts once 4.0 is deprecated/removed. ...so, even if we set the property unconditionally for *all* machine types, then we can still remove it in future, becuase its removal won't affect ABI of the 5.x, 6.x machine types. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|