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Thu, 5 Nov 2026 17:36:27 +0000 (GMT) Received: from [9.68.10.150] (unknown [9.68.10.150]) by smtpav04.dal12v.mail.ibm.com (Postfix) with ESMTP; Thu, 5 Nov 2026 17:36:27 +0000 (GMT) Message-ID: Date: Thu, 5 Nov 2026 18:36:14 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 00/20] Unify code coverage and add Clang source-based coverage with MC/DC To: Sasha Levin , linux-kernel@vger.kernel.org Cc: Adrian Hunter , Alexander Potapenko , Alexander Shishkin , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Anton Ivanov , Arnaldo Carvalho de Melo , Arnd Bergmann , Ben Segall , Bill Wendling , Boqun Feng , Borislav Petkov , Chuck Wolber , Dave Hansen , Dietmar Eggemann , Dmitry Vyukov , Frantisek Hrbata , Frederic Weisbecker , "H. Peter Anvin" , Ian Rogers , Ingo Molnar , James Clark , Jiri Olsa , Johannes Berg , Jonathan Corbet , Josh Poimboeuf , Julian Braha , Juri Lelli , Justin Stitt , kasan-dev@googlegroups.com, K Prateek Nayak , linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org, llvm@lists.linux.dev, Marco Elver , Mark Rutland , Masami Hiramatsu , Mathieu Desnoyers , Mauro Carvalho Chehab , Mel Gorman , Miguel Ojeda , Namhyung Kim , Nathan Chancellor , Nick Desaulniers , Nicolas Schier , Paolo Bonzini , "Paul E. McKenney" , Peter Zijlstra , Randy Dunlap , Richard Weinberger , Sean Christopherson , Shuah Khan , Steven Rostedt , Thomas Gleixner , Valentin Schneider , Vincent Guittot , Waiman Long , Will Deacon , x86@kernel.org, Konstantin Khorenko References: <20261103015238.3780910-1-sashal@kernel.org> From: Peter Oberparleiter Content-Language: en-US In-Reply-To: <20261103015238.3780910-1-sashal@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: 8GuvPdtkZT98o2kwnst12PlIYWYluKM0 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMTA1MDA2OCBTYWx0ZWRfXyQy8yBstwcbM Rkc5xP/dYOg1fgJ+NWjdQN4tVTCYfdKnOtO/mNQOfih1iR+UR2rIx4PUzBiyrdp/D/15qOd1S+o 7IZjnxHupAGDtkaowjEjbpcDPUtbTsI8ybI1rXejxheRgQDgIAGieHRt7+cRQvWxKQ9NzAd+XGG wvLqfJQjTu/uYqe+eJ1U+LoUufrhR9SN4PESkdQUpyVHKRY9nXCI55lmOtuHV7JOr7A9QdIBgzZ 1MXgsu24oErNUM5kwh2EaBpswjBT0mmSDU6TgCmmH2WeVUppSEbeAfMNxVDBG7w9SMwwr+xg5pl I38pfZNQDJfAUYpOaW5jqzTWADH7ovR4dQwk4X5D+A4OjmMnRFV0GPSJ0VVFh0CJ8e3zB8GTK9G EetQPJbvHsM9v29Ud5JKECXRotYWXMk711DpQfJoDP2N66ktbFXYpY+iOwb4q4x4bkcBsCBSokp bW63s937KIzDicIaUCA== X-Proofpoint-Spam-Info: AW1haW4tMjYxMTA1MDA2OCBTYWx0ZWRfX0TAlrJrb+pqq PgBa+KAxcOY+XVOz5FBHXV9251G+GkMlFvSTR4ejT+P1SGyL5tXhByO82fHDlGhDTpDMYnp2U6i oYYAX4uXsMKmzah/S4NgVZDPIqwtByE= X-Authority-Analysis: v=2.4 cv=QK391QLL c=1 sm=1 tr=0 ts=6aecbea7 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=zJRp6_cAMcgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=8BOYBDInhozIBXGn-nEA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: qegOwV1GJ8hxllrcELoypkKbdceA7Ix3 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-11-05_04,2026-11-04_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 impostorscore=0 clxscore=1011 lowpriorityscore=0 adultscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610300000 definitions=main-2611050068 On 03.11.2026 02:52, Sasha Levin wrote: > The previous postings of Clang's source-based code coverage [1][2] drew > objections [3][4]: rather than a third coverage implementation with its > own interface next to gcov and KCOV, reviewers asked for a unified > coverage interface, and for coverage instrumentation to honour noinstr. > This series first restructures the existing coverage support into one > framework, then adds source-based coverage and MC/DC as part of it. Thanks for driving these improvements to the kernel coverage infrastructure! The overall approach taken to unify the different backends looks sane to me, and I'm looking forward to seeing this integrated! I successfully tested the gcov-backend on s390 with GCC 16.1.0, GCC 15.2.0 and latest Clang 24 (git). [...] > - Runtime interface: /sys/kernel/debug/coverage/, with "backend" naming > the backend and its features, "reset" resetting its data, and the > backend's data files. The existing gcov and kcov entries stay where > they are, for lcov and syzkaller, and are linked from there. Just as a FYI - I found a minor incompatibility when using lcov with the series applied where it fails to automatically determine the kernel base directory due to the changed location of gcov-kernel base code, but that's nothing that should affect the kernel series. The issue can be worked around by specifying the path manually and I'm planning to address this with a corresponding lcov change once the series is integrated. -- Peter Oberparleiter Linux on IBM Z Development - IBM Germany R&D