From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F221D606A321 for ; Thu, 29 Oct 2026 08:30:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=Fahvm2F2 Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1xMLVz-0002hz-Pr; Thu, 29 Oct 2026 04:29:39 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xMLVy-0002hr-1e for qemu-devel@nongnu.org; Thu, 29 Oct 2026 04:29:38 -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 1xMLVw-0000Es-85 for qemu-devel@nongnu.org; Thu, 29 Oct 2026 04:29:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1793262573; 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=mKNcAJz3sISh+OBOhDJnM0A4M2G7581aRLKjwyVUh94=; b=Fahvm2F2oJY6MJbbgAQcABv9oG/11aLl5fryxnbnnHlvjI5s3ZLv+A1DRIExOdaWqsn+Ik D9PD/I2lodiYNMCe+t62pSvBzL7RfUGKw3TttOj1/aDQagepE+nfqvSXNB8uZF3UvVZXrO 7Y+xGyr1+nWcwgOwC1BN1UzkbovLb3I= 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-149-rB2iujWUMQ614rNQHGIexQ-1; Thu, 29 Oct 2026 04:29:31 -0400 X-MC-Unique: rB2iujWUMQ614rNQHGIexQ-1 X-Mimecast-MFC-AGG-ID: rB2iujWUMQ614rNQHGIexQ_1793262570 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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 03589180059B; Thu, 29 Oct 2026 08:29:30 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.2]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 04CE930002CF; Thu, 29 Oct 2026 08:29:29 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id A133221E6A04; Thu, 29 Oct 2026 09:29:26 +0100 (CET) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: qemu-devel@nongnu.org, =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Michael Roth , Philippe =?utf-8?Q?Mathieu-Daud?= =?utf-8?Q?=C3=A9?= , Fabiano Rosas , Richard Henderson , "Dr. David Alan Gilbert" , Paolo Bonzini , Pierrick Bouvier , Eric Blake , Laurent Vivier Subject: Re: [PATCH 07/21] util: introduce 'tldr', a system data recorder for crash handling In-Reply-To: <20261015112044.1999748-8-berrange@redhat.com> ("Daniel P. =?utf-8?Q?Berrang=C3=A9=22's?= message of "Thu, 15 Oct 2026 12:20:30 +0100") References: <20261015112044.1999748-1-berrange@redhat.com> <20261015112044.1999748-8-berrange@redhat.com> Date: Thu, 29 Oct 2026 09:29:26 +0100 Message-ID: <87ecd8gba1.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 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: -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, GB_FAKE_RF=0.001, RCVD_IN_DNSWL_LOW=-0.7, 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: qemu development List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Daniel P. Berrang=C3=A9 writes: > Introduce a new subsystem "tldr" aka "thrifty live data recorder" > that will be able to continuously collect certain information at > runtime and dump that in a crash report when QEMU exits abnormally. > As a second use case, it will support manual triggering on interesting > events such as guest OS panic. What's manual about that? > Initially the framework does nothing except print the signal > information. Later commits will introduce broader data collection. > This relies on the dummy siginfo_t struct for portability to Windows. > > Signed-off-by: Daniel P. Berrang=C3=A9 [...] > diff --git a/qapi/qom.json b/qapi/qom.json > index 49f222796ab..1c9031fba9a 100644 > --- a/qapi/qom.json > +++ b/qapi/qom.json > @@ -1233,6 +1233,19 @@ > 'data': { '*pretty': 'bool', > '*close-action': 'MonitorQMPCloseAction' } } >=20=20 > +## > +# @QTLDRConfigProperties: > +# Configuration for data recorder > +# > +# @crash-target: fully qualified path to perserve data recorder > +# contents on QEMU crash What's a "fully qualified path"? Do you mean what POSIX calls "absolute pathname"? Please format member descriptions like this: # @crash-target: fully qualified path to perserve data recorder # contents on QEMU crash > +# > +# Since: 11.2.0 > +## > +{ 'struct': 'QTLDRConfigProperties', > + 'data': { '*crash-target': 'str' } > +} > + > ## > # @ObjectType: > # > @@ -1302,6 +1315,7 @@ > 's390-pv-guest', > 'tdx-guest', > 'throttle-group', > + 'tldr-config', > 'tls-creds-anon', > 'tls-creds-psk', > 'tls-creds-x509', > @@ -1379,6 +1393,7 @@ > 'tdx-guest': 'TdxGuestProperties', > 'thread-context': 'ThreadContextProperties', > 'throttle-group': 'ThrottleGroupProperties', > + 'tldr-config': 'QTLDRConfigProperties', > 'tls-creds-anon': 'TlsCredsAnonProperties', > 'tls-creds-psk': 'TlsCredsPskProperties', > 'tls-creds-x509': 'TlsCredsX509Properties', > diff --git a/qemu-options.hx b/qemu-options.hx > index 2f6863180b0..2f63d86b635 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -6682,6 +6682,20 @@ SRST > :: >=20=20 > (qemu) qom-set /objects/iothread1 poll-max-ns 100000 > + > + > + ``-object tldr-config,id=3Did,crash-target=3Dpath`` > + Creating the ``tldr-config`` object enables the thrifty live data > + recorder, which continuously captures important information about > + the operation of the QEMU process. When a SIGSEGV, SIGBUS, > + SIGILL, SIGFPE or SIGABRT are seen the contents of the data > + recorder will be dumped to the stderr stream. If the > + ``crash-target`` parameter was given, that specifies a fully > + qualified file path to write the dump to instead of stderr. > + > + The ``tldr-config`` object can be added at initial startup > + or via QMP at runtime. Once created, however, it is not > + permitted to disable it. Call the object "tldr"? > ERST >=20=20 >=20=20 [...] > diff --git a/util/tldr-internal.h b/util/tldr-internal.h > new file mode 100644 > index 00000000000..193d8425eee > --- /dev/null > +++ b/util/tldr-internal.h > @@ -0,0 +1,21 @@ > +/* > + * SPDX-License-Identifier: GPL-2.0-or-later > + * > + * TL;DR: Thrifty Live Data Recorder > + * > + * Copyright (C) 2026 Red Hat Inc. > + */ > + > +#ifndef QEMU_TLDR_INTERNAL_H__ > +#define QEMU_TLDR_INTERNAL_H__ > + > +#include "qemu/tldr.h" > + > +#define QTLDR_DUMP_LEADER "\n=F0=9F=9A=A8=F0=9F=9A=A8=F0=9F=9A=A8 QEMU D= ata Recorder Start =F0=9F=9A=A8=F0=9F=9A=A8=F0=9F=9A=A8\n" > +#define QTLDR_DUMP_TRAILER "\n=F0=9F=9A=A8=F0=9F=9A=A8=F0=9F=9A=A8 QEMU = Data Recorder End =F0=9F=9A=A8=F0=9F=9A=A8=F0=9F=9A=A8\n\n" > +#define QTLDR_DUMP_TRIGGER_PREFIX "\n=F0=9F=94=8D Trigger:" > +#define QTLDR_DUMP_OPEN_ERROR "=F0=9F=94=A5 Unable to dump to '" The emojis make the dump file UTF-8. Fine, I guess? > + > +void qtldr_crash_dump_internal(int fd, siginfo_t *si); > + > +#endif /* QEMU_TLDR_INTERNAL_H__ */ [...]