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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 0EF80C43613 for ; Mon, 24 Jun 2019 09:02:52 +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 DA6482089F for ; Mon, 24 Jun 2019 09:02:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DA6482089F 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]:48906 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hfKsE-0004V5-M2 for qemu-devel@archiver.kernel.org; Mon, 24 Jun 2019 05:02:50 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48535) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hfKrQ-0003hr-CO for qemu-devel@nongnu.org; Mon, 24 Jun 2019 05:02:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hfKrJ-0000fa-NY for qemu-devel@nongnu.org; Mon, 24 Jun 2019 05:01:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39668) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hfKrJ-0007Yp-A3 for qemu-devel@nongnu.org; Mon, 24 Jun 2019 05:01:53 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 541E93082E57 for ; Mon, 24 Jun 2019 09:01:27 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-117-169.ams2.redhat.com [10.36.117.169]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D41F5608E4; Mon, 24 Jun 2019 09:01:24 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id D8D8311386A0; Mon, 24 Jun 2019 10:17:33 +0200 (CEST) From: Markus Armbruster To: Igor Mammedov References: <20190620114116.27254-1-imammedo@redhat.com> Date: Mon, 24 Jun 2019 10:17:33 +0200 In-Reply-To: <20190620114116.27254-1-imammedo@redhat.com> (Igor Mammedov's message of "Thu, 20 Jun 2019 07:41:16 -0400") Message-ID: <87blynv1lu.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Mon, 24 Jun 2019 09:01:27 +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 writes: > 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 > --- > 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."); Can we give the user clues on how to avoid the deprecated fallback? Warning message nitpick: the message should be a single phrase, with no newline or trailing punctuation. Suggest something like warn_report("falling back to regular RAM allocation"); error_printf("This is deprecated. \n"); > /* 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. Noch such verb "to fallback", obvious fix "QEMU falls back to" Suggest "RAM, which might". Better: "since the backing file specified by the user is ignored". > 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. What's "system memory allocation"? Perhaps: "In the future, QEMU will not fall back, but fail instead. Adjust either the host configuration [FIXME how?] or the QEMU configuration [FIXME how?]." > + > @section QEMU Machine Protocol (QMP) commands > > @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)