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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7EE1C48BE4 for ; Thu, 27 Jun 2019 19:44:33 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id C866F20665 for ; Thu, 27 Jun 2019 19:44:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C866F20665 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:53958 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hgaJs-0001UW-Up for qemu-devel@archiver.kernel.org; Thu, 27 Jun 2019 15:44:32 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35595) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hgaHd-0000Nq-6b for qemu-devel@nongnu.org; Thu, 27 Jun 2019 15:42:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hgaHY-0006zZ-Qr for qemu-devel@nongnu.org; Thu, 27 Jun 2019 15:42:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40158) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hgaHR-0006FS-Od; Thu, 27 Jun 2019 15:42:01 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id B13843091782; Thu, 27 Jun 2019 19:41:12 +0000 (UTC) Received: from localhost.localdomain (ovpn-123-99.rdu2.redhat.com [10.10.123.99]) by smtp.corp.redhat.com (Postfix) with ESMTP id ECC5619C4F; Thu, 27 Jun 2019 19:41:07 +0000 (UTC) To: Andrea Bolognani , Peter Maydell , Cleber Rosa References: <20190620222314.2670-1-wainersm@redhat.com> <20190621190421.GA679@localhost.localdomain> <7745c47186278c1b7f1781c9173ef0e2e8a55910.camel@redhat.com> From: Wainer dos Santos Moschetta Message-ID: Date: Thu, 27 Jun 2019 16:41:05 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <7745c47186278c1b7f1781c9173ef0e2e8a55910.camel@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Thu, 27 Jun 2019 19:41:17 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [Qemu-arm] [RFC v2 PATCH] hw/arm/virt: makes virt a default machine type 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: qemu-arm , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 06/24/2019 05:37 AM, Andrea Bolognani wrote: > On Sat, 2019-06-22 at 16:58 +0100, Peter Maydell wrote: >> On Fri, 21 Jun 2019 at 20:04, Cleber Rosa wrote: >>> You can consider me biased (I do consider myself), but trying to wear >>> the hat of a user first interacting with QEMU, I would expect a (any) >>> reasonably capable environment that can represent the given target. >>> That will probably be a different environment than the one I may need, >>> and I think that's fine. >> I'm really not sure what you're trying to suggest here; maybe >> you could clarify? If you specify a target (ie a machine type), >> you get that machine type. If you don't specify a target, then >> we can't really guess what you were hoping to run and >> magically pick something that works. >> >> The main problem here is that users expect "all the world is a PC" >> type behaviour, ie they can just provide qemu-system-arm or >> qemu-system-aarch64 with no command line arguments except >> a guest kernel (which is half the time something they found under >> a rock or extracted from some firmware image) or a guest CDROM >> image and have it boot, because that generally works for x86. It >> doesn't and can't work for Arm, because of the much greater >> diversity of machine types and the way that kernels are often >> only compiled to work on a specific subset of machines. >> Making the user specify a machine type means they do at least >> get prompted that the world is more complicated than they >> think it is and there are decisions that have to be made. >> >> In any case even if we did default to "virt" the user still >> has to specify a CPU type, may well also want to provide >> a GIC version (gicv3 being better than the default v2), >> likely more RAM than the very small default, they need to provide >> all the virtio devices, and so on and so on. So giving >> them one option they no longer need to specify doesn't >> really make it any easier IMHO. > Additional note on GIC: most server-grade machines you can buy today > do *not* support GICv2, so you will need to opt-in to GICv3 if you > want your guest to even start. > > More generally, as someone who has worked on supporting non-x86 > guests in libvirt for the past few years, I can tell you from > experience that you're always going to need some arch-specific logic > to deal with the small (and not so small :) differences in behavior > between QEMU targets: as Peter correctly says, machine type is just > a single example among many. > So NACK this patch. I will attempt to address the problem of broken acceptance tests on avocado_qemu side. Thanks Peter, Cleber and Andrea for sharing your opinion. - Wainer