From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 31A52C433EF for ; Wed, 16 Feb 2022 11:24:54 +0000 (UTC) Received: from localhost ([::1]:42260 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nKIQX-0008GN-82 for qemu-devel@archiver.kernel.org; Wed, 16 Feb 2022 06:24:53 -0500 Received: from eggs.gnu.org ([209.51.188.92]:60812) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nKIPq-0007Ou-Be for qemu-devel@nongnu.org; Wed, 16 Feb 2022 06:24:10 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:48388) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nKIPo-0000KC-Oj for qemu-devel@nongnu.org; Wed, 16 Feb 2022 06:24:10 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645010641; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=dNDM/h4xg6d0fEE3idt2myrYsts31lHQA03na0hswHw=; b=QglPDl6WeigrEu1Hp1ZYpXohLjKRZZgefjKpHWjtEX1A0gemK9djM6B/9s+qGga9mq42+2 2gi/7T0dAqjIufKhgsapnMMn+fIpRQ3RkOT7mUUu26u5MwRpTHczDyZB4+8+6XsgE3+05G sDX/Akflj9jPjWL+gQ/rGV3dfkqDnHk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-279-cAIU1zBzM1a4X2CrFEQwng-1; Wed, 16 Feb 2022 06:23:53 -0500 X-MC-Unique: cAIU1zBzM1a4X2CrFEQwng-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1B511801B0B; Wed, 16 Feb 2022 11:23:52 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.245]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1299E60C59; Wed, 16 Feb 2022 11:23:43 +0000 (UTC) Date: Wed, 16 Feb 2022 11:23:41 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: "Dr. David Alan Gilbert" Subject: Re: [PATCH 3/3] x86: Switch to q35 as the default machine type Message-ID: References: <20220215162537.605030-1-dgilbert@redhat.com> <20220215162537.605030-4-dgilbert@redhat.com> <20220216105808.77kqhmsagz3ej74h@sirius.home.kraxel.org> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.1.5 (2021-12-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 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 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.083, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: eduardo@habkost.net, thuth@redhat.com, mst@redhat.com, quintela@redhat.com, qemu-devel@nongnu.org, Gerd Hoffmann , pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Feb 16, 2022 at 11:01:24AM +0000, Dr. David Alan Gilbert wrote: > * Gerd Hoffmann (kraxel@redhat.com) wrote: > > Hi, > > > > > Given the semantic differences from 'i440fx', changing the default > > > machine type has effects that are equivalent to breaking command > > > line syntax compatibility, which is something we've always tried > > > to avoid. > > > > And if we are fine breaking backward compatibility I'd rather *not* pick > > a default, effectively making -M $something mandatory, similar to arm. > > Oh, that's probably easy to do; what are other peoples thoughts on > that? On the libvirt side it won't matter & will have no effect. Libvirt ignores QEMU defaults an explicitly sets 'pc' as the default, so that our users are protected against QEMU changes in defaults that could break app usage. We would of course suggest that all apps using libvirt explicitly pick a machine type they want, but if they dont, we'll set it for them and guarantee that default won't change as long as the machine type exists in QEMU. IOW, whether QEMU selects 'q35' or as the default machine, libvirt will continue to set 'pc' as the default in absence of a mgmt app explicit choice. 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 :|