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 511ECCAC5AC for ; Tue, 23 Sep 2025 13:35:56 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v13A0-0007Np-Nc; Tue, 23 Sep 2025 09:34:24 -0400 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 1v139y-0007M9-Ph for qemu-devel@nongnu.org; Tue, 23 Sep 2025 09:34:22 -0400 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 1v139m-0000Fs-Re for qemu-devel@nongnu.org; Tue, 23 Sep 2025 09:34:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758634444; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=aTrWmxcETLJ2e8j3Sdnb4XPGKEp8ZerxUfv11lHxP3Q=; b=P7TqCZhtlB2ixEDTBo/fPHZLb7gSSGRQf3o+FlUGYGTKlEgkCiW0E4AvUZOzl5k0RIkp73 qkvdMHMkPYeNjDL4+jDz+UKEPtRyY9GhTA3+oUWwPAJEfqAbnYV5wxl3V+scKHrHxJqQJ6 I15dk++NgKiWWXJfJz5OgdNkbK7fAfE= Received: from mx-prod-mc-06.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-376-VKw0cr9vNL-gDPeZYCfjYA-1; Tue, 23 Sep 2025 09:34:01 -0400 X-MC-Unique: VKw0cr9vNL-gDPeZYCfjYA-1 X-Mimecast-MFC-AGG-ID: VKw0cr9vNL-gDPeZYCfjYA_1758634440 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 98B3518004D4; Tue, 23 Sep 2025 13:33:59 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.33]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 18DCF19560BB; Tue, 23 Sep 2025 13:33:59 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 43DA921E6A27; Tue, 23 Sep 2025 15:33:56 +0200 (CEST) From: Markus Armbruster To: Alessandro Ratti Cc: Markus Armbruster , qemu-devel@nongnu.org, Alex =?utf-8?Q?Benn=C3=A9e?= , Daniel P. =?utf-8?Q?Be?= =?utf-8?Q?rrang=C3=A9?= , philmd@linaro.org Subject: Re: [PATCH v2] virtio: Add function name to error messages In-Reply-To: (Alessandro Ratti's message of "Tue, 23 Sep 2025 11:42:44 +0200") References: <87a52wqa03.fsf@draig.linaro.org> <20250915162643.44716-1-alessandro@0x65c.net> <20250915162643.44716-2-alessandro@0x65c.net> <87h5wulqm2.fsf@pond.sub.org> <87wm5qoig7.fsf@draig.linaro.org> <877bxqk6vp.fsf@pond.sub.org> <87a52mh8hl.fsf@pond.sub.org> Date: Tue, 23 Sep 2025 15:33:56 +0200 Message-ID: <87y0q58f97.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 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: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.442, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-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: 2.1.29 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 Alessandro Ratti writes: > On Mon, 22 Sept 2025 at 16:23, Markus Armbruster wrot= e: >> >> Alessandro Ratti writes: >> >> > Hi Markus, Alex, Daniel, >> > >> > Thanks again for the thoughtful feedback and for helping me see the bi= gger >> > picture. I now fully agree that adding function names to error message= s (via >> > __func__) doesn't really address the core issue, and I appreciate the >> > push to rethink how error reporting can better serve both users and de= velopers. >> > >> > I've taken a first stab at improving one of the messages in >> > virtio_init_region_cache(), following your suggestions. >> > >> > Here's the updated call: [...] >> > With this change, the error output now reads: >> > >> > qemu-system-x86_64: Failed to map used ring for device >> > 0000:00:04.0 - possible guest misconfiguration or insufficient memory >> > >> > This feels like a clear improvement =E2=80=94 it gives context (what f= ailed), >> > identifies the device, and hints at likely causes. >> >> It's *much* better! >> >> Developers will appreciate "Failed to map used ring for device". By >> itself it would still be gobbledygook for users, but together with the >> "possible guest misconfiguration or insufficient memory" clue it's fine. >> >> Perhaps we can still improve on "device 0000:00:04.0". The device's ID >> is a good way to identify it to the user, because it's chosen by the >> user, and unique (among devices). Sadly, devices without ID exist. We >> fall back to canonical QOM path in places. Have a look at >> qdev_get_human_name() to see whether it works here. > > I experimented with qdev_get_human_name(), but it usually returns paths l= ike: > > /machine/peripheral-anon/device[0]/virtio-backend > > =E2=80=A6which seems less user-friendly than the PCI address provided by > qdev_get_dev_path(). > For now, I'm sticking to using the device ID when set (e.g. via -device= =E2=80=A6,id=3Dfoo) > and falling back to qdev_get_dev_path() otherwise =E2=80=94 which provide= s predictable > output for both PCI and non-PCI devices. Note that qdev_get_dev_path() may return null. You need another fallback. For what it's worth, "qdev ID or QOM path" is how users specify devices in QMP. [...]