From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 91EFA365A1C; Sun, 15 Mar 2026 14:15:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773584160; cv=none; b=Kb1vP0274wK1Fp9ieIQUB5D0oPNR/xFeyJwyPQxogbHj6Pk1xGWzYHr+nD1wtPylfcNpQVFsFWGA3fL7u/JVgTrTWZxNofLSrsFTx7p5i/PKczU4704nwEpU1PVUCNLH5Zb6P5DDrVgVQecuJs0ZLfMyNWvsSyqIe+xoJJ6njew= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773584160; c=relaxed/simple; bh=agFxp7/+DmzOfwyTxuEGMhbMU3mctxR6EiAxomWVZjA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Nta1fVSyU02JfdJmds1XSAV4zVXRGesroFTgcapL9mtS7x+UsmdrY2K0kBZMxwG+Ljwc7/rlmFOlGHiaV6gQVXiLbAjrSPj64/JT4NAgiPWj2jmcbzrQDu0dJeT2Qdsg/HnqHSIpGCcCbS+KoqBNFy2ITHeAYAKtzQMkhy3XsFk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=roL1M/sn; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="roL1M/sn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7DF01C4CEF7; Sun, 15 Mar 2026 14:15:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773584159; bh=agFxp7/+DmzOfwyTxuEGMhbMU3mctxR6EiAxomWVZjA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=roL1M/sncI7syFKC+9EAQl1eCZCHmJRgd6pDWPCUMZ1EXZw6eMIBYdBqGlooV8+Cz WG3hLBXqLVlZAyHyTeksN6hrbhZxwYTrK7Wd4q8RIbgN1JcM0aQkL0CIRTAxbnky/N llZEm7aaanH9Q+Arg3PCOb5TdJxe8lOcuZ9t2ijKVqCKiy04H4pgFLSfDUtojc9k84 4MyFWx4I3cT5s7XGmir14ybXW295nx5o76Zy7Dtz1gMlHGjQhEZSFXCwkwP5OrFRgK kkqBIrGUBwc5g+NXoR9z7J1yP9qE+pYk0UY42I+bT0OuTv4iqeWqi3wwSlE1yzF+3m 2I9oF3TCISnKw== Date: Sun, 15 Mar 2026 10:15:58 -0400 From: Sasha Levin To: Peter Zijlstra Cc: Chuck Wolber , nathan@kernel.org, Matt.Kelly2@boeing.com, akpm@linux-foundation.org, andrew.j.oppelt@boeing.com, anton.ivanov@cambridgegreys.com, ardb@kernel.org, arnd@arndb.de, bhelgaas@google.com, bp@alien8.de, chuck.wolber@boeing.com, dave.hansen@linux.intel.com, dvyukov@google.com, hpa@zytor.com, jinghao7@illinois.edu, johannes@sipsolutions.net, jpoimboe@kernel.org, justinstitt@google.com, kees@kernel.org, kent.overstreet@linux.dev, linux-arch@vger.kernel.org, linux-efi@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-um@lists.infradead.org, llvm@lists.linux.dev, luto@kernel.org, marinov@illinois.edu, masahiroy@kernel.org, maskray@google.com, mathieu.desnoyers@efficios.com, matthew.l.weber3@boeing.com, mhiramat@kernel.org, mingo@redhat.com, morbo@google.com, ndesaulniers@google.com, oberpar@linux.ibm.com, paulmck@kernel.org, richard@nod.at, rostedt@goodmis.org, samitolvanen@google.com, samuel.sarkisian@boeing.com, steven.h.vanderleest@boeing.com, tglx@linutronix.de, tingxur@illinois.edu, tyxu@illinois.edu, wentaoz5@illinois.edu, x86@kernel.org Subject: Re: [RFC PATCH 0/4] Enable Clang's Source-based Code Coverage and MC/DC for x86-64 Message-ID: References: <20250829181007.GA468030@ax162> <20251014232639.673260-1-sashal@kernel.org> <20251015073701.GZ3419281@noisy.programming.kicks-ass.net> <20251015092145.GB3419281@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20251015092145.GB3419281@noisy.programming.kicks-ass.net> On Wed, Oct 15, 2025 at 11:21:45AM +0200, Peter Zijlstra wrote: >On Wed, Oct 15, 2025 at 08:26:50AM +0000, Chuck Wolber wrote: >> Optimization makes it nearly impossible to correlate GCov results back to >> actual lines of source. llvm-cov instruments at the AST level which enables >> precise mapping back to source code regardless of optimization level. >> >> >> A detailed rundown on this issue can be found here[1], with the most relevant >> excerpt reproduced here: > >Yes read and understand this, but that doesn't mean you have to have 3 >different kernel interfaces for all of this, right? To clarify, are you suggesting that we'll have something like a single /sys/kernel/debug/coverage interface that is producing the same structured output whether we use gcov or llvm? -- Thanks, Sasha