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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5C1CFC433F5 for ; Tue, 26 Oct 2021 09:30:07 +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 DE48260F90 for ; Tue, 26 Oct 2021 09:30:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org DE48260F90 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:39996 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mfImT-0001BX-VH for qemu-devel@archiver.kernel.org; Tue, 26 Oct 2021 05:30:05 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39724) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mfIld-0000S8-Tg for qemu-devel@nongnu.org; Tue, 26 Oct 2021 05:29:13 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:37751) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mfIlb-0008JI-Lb for qemu-devel@nongnu.org; Tue, 26 Oct 2021 05:29:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1635240550; h=from:from:reply-to: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=ZnS5XAyrzUF7dwHsXtTxEobLkp1GiLOifkI3t6wLRpE=; b=VGTBOJUmXcCajmS7PEpo2Nz5Gi0EID2L1YHOxaC63PYi77Tk0XBcm25F1CsuY0yLu8iQE1 pHzr0POe5Yd03mKDr3EliZAtIn/lUUpRkRYDkf1G7+jmhyLj5LmQeLAYpG3xCVBF+LXPgr bSo37Ip2ZbPt4qIo3Wa93y6iuRnZrWo= 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-450-jv4w8C8sP-eNFB5vdwvuNw-1; Tue, 26 Oct 2021 05:28:55 -0400 X-MC-Unique: jv4w8C8sP-eNFB5vdwvuNw-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 958FA5074E; Tue, 26 Oct 2021 09:28:54 +0000 (UTC) Received: from redhat.com (unknown [10.39.195.123]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C818C5C1A1; Tue, 26 Oct 2021 09:28:27 +0000 (UTC) Date: Tue, 26 Oct 2021 10:28:25 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: "Dr. David Alan Gilbert" Subject: Re: [PATCH 1/9] qapi: New special feature flag "unstable" Message-ID: References: <20211025052532.3859634-1-armbru@redhat.com> <20211025052532.3859634-2-armbru@redhat.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.0.7 (2021-05-04) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H2=-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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Kevin Wolf , pkrempa@redhat.com, mdroth@linux.vnet.ibm.com, qemu-block@nongnu.org, quintela@redhat.com, libvir-list@redhat.com, eblake@redhat.com, Markus Armbruster , qemu-devel@nongnu.org, pbonzini@redhat.com, marcandre.lureau@redhat.com, jsnow@redhat.com, libguestfs@redhat.com, ehabkost@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Oct 26, 2021 at 10:22:15AM +0100, Dr. David Alan Gilbert wrote: > * Kevin Wolf (kwolf@redhat.com) wrote: > > Am 25.10.2021 um 07:25 hat Markus Armbruster geschrieben: > > > By convention, names starting with "x-" are experimental. The parts > > > of external interfaces so named may be withdrawn or changed > > > incompatibly in future releases. > > > > > > Drawback: promoting something from experimental to stable involves a > > > name change. Client code needs to be updated. > > > > > > Moreover, the convention is not universally observed: > > > > > > * QOM type "input-barrier" has properties "x-origin", "y-origin". > > > Looks accidental, but it's ABI since 4.2. > > > > > > * QOM types "memory-backend-file", "memory-backend-memfd", > > > "memory-backend-ram", and "memory-backend-epc" have a property > > > "x-use-canonical-path-for-ramblock-id" that is documented to be > > > stable despite its name. > > > > > > We could document these exceptions, but documentation helps only > > > humans. We want to recognize "unstable" in code, like "deprecated". > > > > > > Replace the convention by a new special feature flag "unstable". It > > > will be recognized by the QAPI generator, like the existing feature > > > flag "deprecated", and unlike regular feature flags. > > > > > > This commit updates documentation and prepares tests. The next commit > > > updates the QAPI schema. The remaining patches update the QAPI > > > generator and wire up -compat policy checking. > > > > > > Signed-off-by: Markus Armbruster > > > > Obviously, replacing the old convention gets rid of the old drawbacks, > > but adds a new one: While using x- makes it very obvious for a human > > user that this is an unstable feature, a feature flag in the schema will > > almost certainly go unnoticed in manual use. > > Agreed, I'd keep the x- as well. > > Having said that, the x- represents a few different things (that we > don't currently distinguish): > - experimental > - for internal use > - for debugging/human use All of those usage scenarios have the same implication though: Command/data format is liable to change in incompatible ways, or be deleted, with no prior warning. I don't think we need to distinguish the use cases - some commands may belong to two or three of those use cases. All that matters is that they're considered "unstable" from an API compat POV. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|