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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, T_HK_NAME_DR,USER_AGENT_MUTT 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 43A41C43613 for ; Thu, 20 Jun 2019 14:09:55 +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 1508520679 for ; Thu, 20 Jun 2019 14:09:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1508520679 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]:48016 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hdxlB-0005u4-MK for qemu-devel@archiver.kernel.org; Thu, 20 Jun 2019 10:09:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52975) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hdxPN-0005JZ-BG for qemu-devel@nongnu.org; Thu, 20 Jun 2019 09:47:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hdxPL-0004CU-DZ for qemu-devel@nongnu.org; Thu, 20 Jun 2019 09:47:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43096) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hdxCs-00057V-KU for qemu-devel@nongnu.org; Thu, 20 Jun 2019 09:34:26 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id 667EE37F41 for ; Thu, 20 Jun 2019 13:34:15 +0000 (UTC) Received: from work-vm (ovpn-117-203.ams2.redhat.com [10.36.117.203]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 077D45D9D2; Thu, 20 Jun 2019 13:34:11 +0000 (UTC) Date: Thu, 20 Jun 2019 14:34:09 +0100 From: "Dr. David Alan Gilbert" To: Igor Mammedov Message-ID: <20190620133409.GA5910@work-vm> References: <20190620114116.27254-1-imammedo@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190620114116.27254-1-imammedo@redhat.com> User-Agent: Mutt/1.11.4 (2019-03-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Thu, 20 Jun 2019 13:34:15 +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] [PATCH] deprecate -mem-path fallback to anonymous RAM 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: libvir-list@redhat.com, qemu-devel@nongnu.org, ehabkost@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Igor Mammedov (imammedo@redhat.com) wrote: > Fallback might affect guest or worse whole host performance > or functionality if backing file were used to share guest RAM > with another process. > > Patch deprecates fallback so that we could remove it in future > and ensure that QEMU will provide expected behavior and fail if > it can't use user provided backing file. > > Signed-off-by: Igor Mammedov Ah yes that's useful because it's a mess for postcopy. Reviewed-by: Dr. David Alan Gilbert > --- > PS: > Patch is written on top of > [PATCH v4 0/3] numa: deprecate '-numa node, mem' and default memory distribution > to avoid conflicts in qemu-deprecated.texi > > numa.c | 4 ++-- > qemu-deprecated.texi | 8 ++++++++ > 2 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/numa.c b/numa.c > index 91a29138a2..53d67b8ad9 100644 > --- a/numa.c > +++ b/numa.c > @@ -494,8 +494,8 @@ static void allocate_system_memory_nonnuma(MemoryRegion *mr, Object *owner, > if (mem_prealloc) { > exit(1); > } > - error_report("falling back to regular RAM allocation."); > - > + warn_report("falling back to regular RAM allocation. " > + "Fallback to RAM allocation is deprecated."); > /* Legacy behavior: if allocation failed, fall back to > * regular RAM allocation. > */ > diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi > index 2fe9b72121..2193705644 100644 > --- a/qemu-deprecated.texi > +++ b/qemu-deprecated.texi > @@ -112,6 +112,14 @@ QEMU using implicit generic or board specific splitting rule. > Use @option{memdev} with @var{memory-backend-ram} backend or @option{mem} (if > it's supported by used machine type) to define mapping explictly instead. > > +@subsection -mem-path fallback to RAM (since 4.1) > +Currently if system memory allocation from file pointed by @option{mem-path} > +fails, QEMU fallbacks to allocating from anonymous RAM. Which might result > +in unpredictable behavior since provided backing file wasn't used. In future > +QEMU will not fallback and fail to start up, so user could fix his/her QEMU/host > +configuration or explicitly use -m without -mem-path if system memory allocated > +from anonymous RAM suits usecase. > + > @section QEMU Machine Protocol (QMP) commands > > @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0) > -- > 2.18.1 > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK