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 F2A1EC433EF for ; Tue, 26 Oct 2021 08:12:54 +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 686CA60C49 for ; Tue, 26 Oct 2021 08:12:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 686CA60C49 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]:44176 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mfHZl-0001Ey-BQ for qemu-devel@archiver.kernel.org; Tue, 26 Oct 2021 04:12:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57810) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mfGgj-0006id-F5 for qemu-devel@nongnu.org; Tue, 26 Oct 2021 03:16:02 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:52106) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mfGgb-0005oX-11 for qemu-devel@nongnu.org; Tue, 26 Oct 2021 03:15:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1635232551; 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=jEypT7jEkdu4PHalUKyhVSzF+9hHejOaPFLiUAhzYCU=; b=RxD68uR51C2p4rsK+CWmcW/rMe9URQBLsHKDbJwgmTV77Hm1C50T95Qxp++S7usfmYhp4Z x6HBf8TzVC8Z49m4CX9jD+U0r7ySQ0gFMlUgpwFP5SkFc8H+HI1uYpp2hVo0443Z8iCiUm w4lCkK7yYekIPvA0NS/GEopLulmUaNU= 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-521-p7UaV0oQO4eNG0ksmzFlpg-1; Tue, 26 Oct 2021 03:15:46 -0400 X-MC-Unique: p7UaV0oQO4eNG0ksmzFlpg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 874C21054F98; Tue, 26 Oct 2021 07:15:45 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-112-7.ams2.redhat.com [10.36.112.7]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7FA065D705; Tue, 26 Oct 2021 07:15:32 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id F2A9C11380A7; Tue, 26 Oct 2021 09:15:30 +0200 (CEST) From: Markus Armbruster To: Kashyap Chamarthy Subject: Re: [PATCH 1/9] qapi: New special feature flag "unstable" References: <20211025052532.3859634-1-armbru@redhat.com> <20211025052532.3859634-2-armbru@redhat.com> Date: Tue, 26 Oct 2021 09:15:30 +0200 In-Reply-To: (Kashyap Chamarthy's message of "Mon, 25 Oct 2021 14:05:00 +0200") Message-ID: <87v91k6yul.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=armbru@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Received-SPF: pass client-ip=216.205.24.124; envelope-from=armbru@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: , Cc: kwolf@redhat.com, pkrempa@redhat.com, berrange@redhat.com, ehabkost@redhat.com, qemu-block@nongnu.org, quintela@redhat.com, libvir-list@redhat.com, qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com, libguestfs@redhat.com, marcandre.lureau@redhat.com, pbonzini@redhat.com, eblake@redhat.com, dgilbert@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Kashyap Chamarthy writes: > On Mon, Oct 25, 2021 at 07:25:24AM +0200, Markus Armbruster wrote: >> 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. > > Looks like there's another stable property with an "x-" prefix: > "x-remote-object", part of QOM type @RemoteObjectProperties. The union branch 'x-remote-object' isn't flagged 'unstable' (because union branches can't have feature flags), but the enumeration value 'x-remote-object' is. Sufficient, because you can't use the branch without using the enumeration value. Admittedly subtle. I wrote a bit of code (appended) to make sure I don't miss names. > Given the above "x-" properties are now stable, I take it that they > cannot be renamed now, as they might break any tools using them? My > guess is the tedious way is not worth it: deprecate them, and add the > non-x variants as "synonyms". "x-use-canonical-path-for-ramblock-id" goes back to commit fa0cb34d22 "hostmem: use object id for memory region name with >= 4.0" (v4.0). It may have been intended to be internal back then. It wasn't anymore when commit 8db0b20415 "machine: add missing doc for memory-backend option" (v6.0) documented 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. x- was intended for unstable/iternal properties, and not supposed to be stable option. However it's too late to rename (drop x-) it as it would mean that users will have to mantain both x-use-canonical-path-for-ramblock-id (for QEMU 5.0-5.2) versions and prefix-less for later versions. Igor's reasoning still applies. "x-origin" has always been stable. Same argument. >> 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. > > FWIW, sounds good to me. Thanks! >> 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 >> --- >> docs/devel/qapi-code-gen.rst | 9 ++++++--- >> tests/qapi-schema/qapi-schema-test.json | 7 +++++-- >> tests/qapi-schema/qapi-schema-test.out | 5 +++++ >> 3 files changed, 16 insertions(+), 5 deletions(-) > > [...] commit 415b71a9f6e5bc37e84895d2e767cf4cfacd279b (HEAD) Author: Markus Armbruster Date: Sat Oct 9 09:01:21 2021 +0200 qapi: Find x- without feature unstable DBG diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py index b7b3fc0ce4..f2af1d7eea 100644 --- a/scripts/qapi/schema.py +++ b/scripts/qapi/schema.py @@ -14,6 +14,8 @@ # TODO catching name collisions in generated code would be nice +import sys + from collections import OrderedDict import os import re @@ -118,6 +120,11 @@ def describe(self): return "%s '%s'" % (self.meta, self.name) +def check_have_feature_unstable(name, info, features): + if name.startswith('x-') and 'unstable' not in (f.name for f in features): + print(QAPISemError(info, f"XXX %{name} %{features}"), file=sys.stderr) + + class QAPISchemaVisitor: def visit_begin(self, schema): pass @@ -718,6 +725,7 @@ def __init__(self, name, info, ifcond=None, features=None): self.features = features or [] def connect_doc(self, doc): + check_have_feature_unstable(self.name, self.info, self.features) super().connect_doc(doc) if doc: for f in self.features: @@ -745,6 +753,7 @@ def __init__(self, name, info, typ, optional, ifcond=None, features=None): self.features = features or [] def check(self, schema): + check_have_feature_unstable(self.name, self.info, self.features) assert self.defined_in self.type = schema.resolve_type(self._type_name, self.info, self.describe) @@ -789,6 +798,7 @@ def __init__(self, name, info, doc, ifcond, features, def check(self, schema): super().check(schema) + check_have_feature_unstable(self.name, self.info, self.features) if self._arg_type_name: self.arg_type = schema.resolve_type( self._arg_type_name, self.info, "command's 'data'") @@ -844,6 +854,7 @@ def __init__(self, name, info, doc, ifcond, features, arg_type, boxed): def check(self, schema): super().check(schema) + check_have_feature_unstable(self.name, self.info, self.features) if self._arg_type_name: self.arg_type = schema.resolve_type( self._arg_type_name, self.info, "event's 'data'")