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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id B2F26C48BF8 for ; Mon, 19 Feb 2024 15:19:19 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rc5Q1-0008DT-Vu; Mon, 19 Feb 2024 10:18:58 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rc5Q0-0008D4-Ag for qemu-devel@nongnu.org; Mon, 19 Feb 2024 10:18:56 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rc5Py-0004WD-RH for qemu-devel@nongnu.org; Mon, 19 Feb 2024 10:18:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1708355934; 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=fu8/Mt2aSHQuTJ845USkw9KXJ7rUafATcJ5jr+Y/klA=; b=exlpeZbSO3jxAFn54wfjQNs04yhxxEbOYHffNGIWDKvVh/dI4cyTh+f+JIlQvPDCgfXQn9 Os5uEafR5X0owKuvtCAxNuZhRdlX67cPE69KpHw3f+2UYB8ra23qI8OSUHkl4ly74LgylM G3YrrfzFBmDTpEVMhYJtGcMWvI8JU48= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-88-8lCE89LmM_ie_TvEAQDJqg-1; Mon, 19 Feb 2024 10:18:50 -0500 X-MC-Unique: 8lCE89LmM_ie_TvEAQDJqg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6D1EE10AF98A; Mon, 19 Feb 2024 15:18:50 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.55]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4B0D12166B34; Mon, 19 Feb 2024 15:18:49 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 3971821E6767; Mon, 19 Feb 2024 16:18:43 +0100 (CET) From: Markus Armbruster To: Hyman Huang Cc: qemu-devel@nongnu.org, "Michael S . Tsirkin" , Eric Blake Subject: Re: [PATCH v3 1/3] qmp: Switch x-query-virtio-status back to numeric encoding In-Reply-To: (Hyman Huang's message of "Fri, 2 Feb 2024 22:32:15 +0800") References: Date: Mon, 19 Feb 2024 16:18:43 +0100 Message-ID: <87plwsiiss.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.072, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hyman Huang writes: > x-query-virtio-status returns several sets of virtio feature and > status flags. It goes back to v7.2.0. > > In the initial commit 90c066cd682 (qmp: add QMP command > x-query-virtio-status), we returned them as numbers, using virtio's > well-known binary encoding. > > The next commit f3034ad71fc (qmp: decode feature & status bits in > virtio-status) replaced the numbers by objects. The objects represent > bits QEMU knows symbolically, and any unknown bits numerically just like > before. > > Commit 8a8287981d1 (hmp: add virtio commands) the matching HMP command added the matching HMP command > "info virtio" (and a few more, which aren't relevant here). > > The symbolic representation uses lists of strings. The string format is > undocumented. The strings look like "WELL_KNOWN_SYMBOL: human readable > explanation". > > This symbolic representation is nice for humans. Machines it can save > the trouble of decoding virtio's well-known binary encoding. > > However, we sometimes want to compare features and status bits without > caring for their exact meaning. Say we want to verify the correctness > of the virtio negotiation between guest, QEMU, and OVS-DPDK. We can use > QMP command x-query-virtio-status to retrieve vhost-user net device > features, and the "ovs-vsctl list interface" command to retrieve > interface features. Without commit f3034ad71fc, we could then simply > compare the numbers. With this commit, we first have to map from the > strings back to the numeric encoding. > > Revert the decoding for QMP, but keep it for HMP. > > This makes the QMP command easier to use for use cases where we > don't need to decode, like the comparison above. For use cases > where we need to decode, we replace parsing undocumented strings by > decoding virtio's well-known binary encoding. > > Incompatible change; acceptable because x-query-virtio-status does Scratch "does". > comes without a stability promise. > > Signed-off-by: Hyman Huang Acked-by: Markus Armbruster