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 68A94D65C4F for ; Wed, 17 Dec 2025 14:26:32 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vVsTv-00088x-Lf; Wed, 17 Dec 2025 09:26:24 -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 1vVsTt-00088V-QP for qemu-arm@nongnu.org; Wed, 17 Dec 2025 09:26:21 -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 1vVsTs-0005R4-5h for qemu-arm@nongnu.org; Wed, 17 Dec 2025 09:26:21 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1765981578; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5IgMFFYlcBbJ8au/MCT9FF9PvoXgAcN4CgVR5pL1QDQ=; b=d2uvpl9k9fq5jRoYZ8zzarrgRhl30amUppdWzerkT5Pvljy8VwNYp2DooQxH1I9EDl9pQb Ljte9KQG7I69Cwh1hB2Xy/0ztesF1CpP2Oioss/Gnse31xjpn90jGUPwuyRHqMnYODjQNl l+RVPCsR5rrGIuXuFOQ/GZdpwC/3ugE= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-76-ql8OFvLxM9eCvrneUtZdgQ-1; Wed, 17 Dec 2025 09:26:16 -0500 X-MC-Unique: ql8OFvLxM9eCvrneUtZdgQ-1 X-Mimecast-MFC-AGG-ID: ql8OFvLxM9eCvrneUtZdgQ_1765981574 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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 mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B14571800621; Wed, 17 Dec 2025 14:26:14 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.217]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3544930001A2; Wed, 17 Dec 2025 14:26:11 +0000 (UTC) Date: Wed, 17 Dec 2025 14:26:07 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Cc: qemu-devel@nongnu.org, "Michael S . Tsirkin" , Eugenio =?utf-8?B?UMOpcmV6?= , Manos Pitsidianakis , devel@lists.libvirt.org, Richard Henderson , Peter Maydell , qemu-arm@nongnu.org, Jason Wang , Alex =?utf-8?Q?Benn=C3=A9e?= Subject: Re: [PATCH] hw/arm: Deprecate legacy VirtIO devices on big-endian guests Message-ID: References: <20251217140658.89715-1-philmd@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20251217140658.89715-1-philmd@linaro.org> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 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: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-arm@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-arm-bounces+qemu-arm=archiver.kernel.org@nongnu.org Sender: qemu-arm-bounces+qemu-arm=archiver.kernel.org@nongnu.org On Wed, Dec 17, 2025 at 03:06:57PM +0100, Philippe Mathieu-Daudé wrote: > We couldn't find a way (guest OS with VirtIO drivers) to test > a legacy VirtIO device on a ARM vCPU running in big-endian. > > Deprecate for the v11.0 release, giving 1 year to users who > really care to contribute functional tests. > > Suggested-by: Alex Bennée > Signed-off-by: Philippe Mathieu-Daudé > --- > docs/about/deprecated.rst | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst > index ac31a2bce42..3a69facb0f1 100644 > --- a/docs/about/deprecated.rst > +++ b/docs/about/deprecated.rst > @@ -515,6 +515,17 @@ It was implemented as a no-op instruction in TCG up to QEMU 9.0, but > only with ``-cpu max`` (which does not guarantee migration compatibility > across versions). > > +VirtIO devices > +'''''''''''''' > + > +Legacy VirtIO devices on Big-Endian ARM architecture (since 11.0) > +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > + > +There are no functional tests for legacy virtio devices used by ARM > +machines running in big-endian order, which makes harder to maintain > +the code path while the code base evolve. Lack of test coverage is not a reason to deprecate something. We deprecate things we intend to intentionally remove or intentionally change in an incompatible manner. If something is not tested, that merely means it has lesser quality guarantees, and is liable to unintenionally get broken at times. If we're planning to *intentionally* remove the ability to use legacy virtio on big endian, that would be a reason to deprecate. If so the deprecation message should say this, not talk about missing functional testing. With 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 :|