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 A571BCAC583 for ; Tue, 9 Sep 2025 11:23:52 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uvwR5-00082b-Iw; Tue, 09 Sep 2025 07:22:56 -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 1uvwQz-00081a-AE for qemu-devel@nongnu.org; Tue, 09 Sep 2025 07:22:49 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uvwQr-0006BZ-QM for qemu-devel@nongnu.org; Tue, 09 Sep 2025 07:22:49 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1757416957; 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=zZuFo7C7Jz4OAynZGsPU3CYiGUn+fE3QqRU/rjiP1fI=; b=d3iLrQch7jAzjNvnJhrFxoAN9l+T5owzlzqC2694oAydikVTCiihOZ67A3dDi5CR6yJpe7 ggpiwh7iznomfkeBsp98ved9yEyZTQiJGqeUxLxKvPET9h47hPAeCUrMfdzenEv4W51CI/ RH/80rZyphrpcd5x6BfwluP2vdlUhh8= 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-379-kzaBJaxNMs-4wvIsFka1ww-1; Tue, 09 Sep 2025 07:22:34 -0400 X-MC-Unique: kzaBJaxNMs-4wvIsFka1ww-1 X-Mimecast-MFC-AGG-ID: kzaBJaxNMs-4wvIsFka1ww_1757416953 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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 D45BC180057A; Tue, 9 Sep 2025 11:22:32 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.18]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 57B711800578; Tue, 9 Sep 2025 11:22:32 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id CD9BC21E6A27; Tue, 09 Sep 2025 13:22:29 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: qemu-devel@nongnu.org, odaki@rsg.ci.i.u-tokyo.ac.jp, marcandre.lureau@redhat.com, Alex =?utf-8?Q?Benn=C3=A9e?= Subject: Re: [PATCH 01/12] monitor: Clean up HMP gdbserver error reporting In-Reply-To: ("Daniel P. =?utf-8?Q?Berrang?= =?utf-8?Q?=C3=A9=22's?= message of "Tue, 19 Aug 2025 11:53:21 +0100") References: <20250808080823.2638861-1-armbru@redhat.com> <20250808080823.2638861-2-armbru@redhat.com> Date: Tue, 09 Sep 2025 13:22:29 +0200 Message-ID: <87ikhrzx8q.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 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@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_H5=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-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 Daniel P. Berrang=C3=A9 writes: > On Fri, Aug 08, 2025 at 10:08:12AM +0200, Markus Armbruster wrote: >> HMP command gdbserver used to emit two error messages for certain >> errors. For instance, with -M none: >>=20 >> (qemu) gdbserver >> gdbstub: meaningless to attach gdb to a machine without any CPU. >> Could not open gdbserver on device 'tcp::1234' >>=20 >> The first message is the specific error, and the second one a generic >> additional message that feels superfluous to me. >>=20 >> Commit c0e6b8b798b (system: propagate Error to gdbserver_start (and >> other device setups)) turned the first message into a warning: >>=20 >> warning: gdbstub: meaningless to attach gdb to a machine without any= CPU. >> Could not open gdbserver on device 'tcp::1234' >>=20 >> This is arguably worse. >>=20 >> hmp_gdbserver() passes &error_warn to gdbserver_start(), so that >> failure gets reported as warning, and then additionally emits the >> generic error on failure. This is a misuse of &error_warn. >>=20 >> Instead, receive the error in &err and report it, as usual. With >> this, gdbserver reports just the error: >>=20 >> gdbstub: meaningless to attach gdb to a machine without any CPU. > > What do you think about an alternative of removing "gdbstub: " > from all the errors raised in 'gdbserver_start' & similar, and > then using > > error_prepend(err, "Could not open gdbserver on device '%s'", device); > > in hmp_gdbserver ? This would change the error message from (qemu) gdbserver=20 gdbstub: meaningless to attach gdb to a machine without any CPU. to (qemu) gdbserver=20 Could not open gdbserver on device 'tcp::1234': meaningless to attach g= db to a machine without any CPU. Longer, but doesn't tell me anything new beyond reminding me that gdbserver's argument defaults to "tcp::1234". This instance of gdbserver_start() is additionally called by qemu_machine_creation_done() in system/vl.c on behalf of command line option gdb. The error message would change from $ qemu-system-x86_64 -M none -gdb "" qemu-system-x86_64: -gdb : gdbstub: meaningless to attach gdb to a mach= ine without any CPU. to $ qemu-system-x86_64 -M none -gdb "" qemu-system-x86_64: -gdb : meaningless to attach gdb to a machine witho= ut any CPU. Improvement. Howver, we better drop the prefix from all error messages emitted here, not just this one. There's another instance of gdbserver_start() in gdbstub/user.c, called by main() in bsduser/main.c and in linux-user/main.c on behalf of command line option -g / -gdb. Same silly prefix: $ qemu-x86_64 -g x,y /bin/ls qemu-x86_64: gdbstub: unknown option "y" Usage: -g {port|path}[,suspend=3D{y|n}] > I don't feel too strongly, so in any case for the patch as is, Separate patch to strip "gdbstub: " from all error messages? > Reviewed-by: Daniel P. Berrang=C3=A9 Thanks!