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=-7.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 003F0C0650F for ; Fri, 2 Aug 2019 22:34:30 +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 C44A22087E for ; Fri, 2 Aug 2019 22:34:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C44A22087E 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]:37836 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1htg86-0002ll-55 for qemu-devel@archiver.kernel.org; Fri, 02 Aug 2019 18:34:30 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59104) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1htg7T-0002Ld-9J for qemu-devel@nongnu.org; Fri, 02 Aug 2019 18:33:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1htg7R-0006Me-GI for qemu-devel@nongnu.org; Fri, 02 Aug 2019 18:33:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47574) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1htg7R-0006MG-Ae for qemu-devel@nongnu.org; Fri, 02 Aug 2019 18:33:49 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 636932DD3B; Fri, 2 Aug 2019 22:33:47 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-116-36.ams2.redhat.com [10.36.116.36]) by smtp.corp.redhat.com (Postfix) with ESMTP id E0593600C1; Fri, 2 Aug 2019 22:33:41 +0000 (UTC) To: Peter Maydell References: <20190729125755.45008-1-slp@redhat.com> <932a0c3c-b6cb-540f-ca07-1559c8fe9049@redhat.com> <9953cc99-80b3-814c-f75e-a16c987c23e5@redhat.com> <9b2acff6-8c6d-3aa0-8020-d6d831222496@redhat.com> From: Laszlo Ersek Message-ID: <665148f7-8b64-e6df-cd43-ee1306c7878a@redhat.com> Date: Sat, 3 Aug 2019 00:33:40 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 02 Aug 2019 22:33:47 +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] [RFC] virtio-mmio: implement modern (v2) personality (virtio-1) 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: Paolo Bonzini , qemu-devel , Sergio Lopez Pascual , "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 08/02/19 11:20, Peter Maydell wrote: > On Fri, 2 Aug 2019 at 01:26, Laszlo Ersek wrote: >> But it's extra work, not entirely risk-free (regressions), and I can't >> tell if someone out there still uses virtio-mmio (despite me thinking >> that would be unreasonable). I wouldn't like to see more work sunk into >> it either way :) > > The main reasons I still see people using virtio-mmio for > the 'virt' board are: > * still using old but working command lines > * newer setups that were put together working from older tutorials > that recommended virtio-mmio because they predated virtio-pci > support being widespread > * using older (eg distro) kernels -- for 32-bit kernels in > particular it was a while before the virtio-pci support > got built in the default configs I think, and then longer > again until those got into stable distro releases There was one time when edk2 core modules gained a feature for marking the DXE phase stack non-executable. We happily enabled it in OVMF. Then people reported that UEFI grub in their old Debian guests had broken -- on their hosts carrying OVMF binaries built from upstream. :) We had to flip the default off in OVMF, and we've stuck with that ever since... https://github.com/tianocore/edk2/commit/d20b06a3afdf > I wouldn't be surprised if some of those applied also to > via-OVMF boot setups as well as direct kernel boot. So it > depends a bit what your tolerance for breaking existing > user setups is. Near zero. :) Thanks Laszlo