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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 195CEC433DB for ; Fri, 15 Jan 2021 10:44:17 +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 50FF3233CF for ; Fri, 15 Jan 2021 10:44:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 50FF3233CF 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]:40606 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l0MaV-0002X4-7t for qemu-devel@archiver.kernel.org; Fri, 15 Jan 2021 05:44:15 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:60498) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l0MZi-00026s-0y for qemu-devel@nongnu.org; Fri, 15 Jan 2021 05:43:26 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:54935) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l0MZd-0007tr-Hu for qemu-devel@nongnu.org; Fri, 15 Jan 2021 05:43:25 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610707399; h=from:from: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=8nIT9RxP5hozqX55lfuhf2braxQWNddqA8JFV1yPA0o=; b=hS01Zw74yz0wFbFWbYj3ppFdmFXZEdH+rlHmVzwlgqS699KHLsUCXCsOluqVhALV2FA4lp 5SrO5go3jdd204FNuDKdFK9FG+7kd/yN/sz3JsKcqtFnhGFFkkmFec2PMjXBkb4yHF/Nu6 dwc32UNEO6JUKrJ7/jkXbveemqn35fQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-209-yf7Ckd5SPxSyrP6g5A7sLQ-1; Fri, 15 Jan 2021 05:43:18 -0500 X-MC-Unique: yf7Ckd5SPxSyrP6g5A7sLQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D9EAA806664; Fri, 15 Jan 2021 10:43:16 +0000 (UTC) Received: from angien.pipo.sk (unknown [10.40.208.30]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 506E671D5E; Fri, 15 Jan 2021 10:43:15 +0000 (UTC) Date: Fri, 15 Jan 2021 11:43:10 +0100 From: Peter Krempa To: Peter Maydell Subject: Re: [PATCH v2] machine: add missing doc for memory-backend option Message-ID: <20210115104310.GA2794356@angien.pipo.sk> References: <20210114234612.795621-1-imammedo@redhat.com> MIME-Version: 1.0 In-Reply-To: X-PGP-Key-ID: 0xD018682B X-PGP-Key-Fingerprint: D294 FF38 A6A2 BF40 6C75 5DEF 36EC 16AC D018 682B User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pkrempa@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=pkrempa@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.248, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: Igor Mammedov , Paolo Bonzini , QEMU Developers , Michal Privoznik Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Jan 15, 2021 at 10:02:04 +0000, Peter Maydell wrote: > On Thu, 14 Jan 2021 at 23:48, Igor Mammedov wrote: > > > > Add documentation for '-machine memory-backend' CLI option and > > how to use it. > > > > And document that x-use-canonical-path-for-ramblock-id, > > is considered to be stable to make sure it won't go away by accident. > > That's not what the x- prefix is supposed to mean. This is the exact reason I was asking on behalf of the libvirt team for adding such statement if we were to use it. We want guarantee that it's considered stable since without that it will not be accepted into libvirt. > If we have an internal constraint that we mustn't delete > the option in order to support some other must-be-stable > interface (eg migration of some machines) we can document > that in a comment, but that doesn't mean that we should > document to users that direct use of an x-prefix option > is supported as a stable interface. AFAIK the issue is that with the new approach to configure system memory (via a memory-backend=id, since the old one was deprecated) migration fails from/to older qemus ... > Alternatively, if the option is really stable for direct > use by users then we should commit to making it so by > removing the x-. ... thus the idea behind keeping this interface as is is it also fixes the migration compatibility for qemu 5.0/5.1/5.2 which were already released. Removing the 'x-' will fix it only starting with qemu-6.0 and any downstream which backports the removal of the prefix. Obviously not using 'x-' prefixed options is strongly preferred in libvirt.