From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm2-f13.google.com (mail-wm2-f13.google.com [74.125.225.141]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2573F49AA2E for ; Mon, 21 Sep 2026 12:36:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.225.141 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789994198; cv=none; b=NsuEMsKZJUI6Iclh0M6/9578IZ9+lL6vCQdqm+0toat/BqgFbIT6w+snn9SRxsiDfpyyA07HMdpNFF11hbeWR0B6UuiB1weX9yyATYRrPT83VYj9conDXrpyCXvc77w90kZmfV19RCjBss901I1TgzuXIaYOOZZoY8Nwni2l79A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789994198; c=relaxed/simple; bh=mbYQBjqI+FvjSHjgV1FgOANO3gDLaxDS3IAWnqfDmCM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=BvKcHIlzcMF1ETFexiNLGPuo2fhtWdugUaOBp6faCfIECciXSyrQnO4lF+QbEZHoVcQkHX3BtzTcLwzQYqUSc1BvgKVltt5xdm9B2V5X3aEOPbW7qm02wFuvFKDK6A7z+DkmWUAvCgTL9zrP3GOL6RB/joiGMgt749NLG+KyIwQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=N/t77jSA; arc=none smtp.client-ip=74.125.225.141 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="N/t77jSA" Received: by mail-wm2-f13.google.com with SMTP id 5b1f17b1804b1-49e79a408deso16415255e9.2 for ; Mon, 21 Sep 2026 05:36:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1789994193; x=1790598993; darn=vger.kernel.org; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to :content-type; bh=8SRT9W/2z9fLq6Pj3t4dd8eEawuNLFrl/C3bQijqfHo=; b=N/t77jSAvT1buLGD4Z3b8ts5eS3gjhm0OF4vn0Uosbh8OjneLL9DAYdLMOVZJggWoF rbIE2yG27HyQlIoj4mXIWiL/oC8s+oVmWt1nJyhmAybPVILHioPJXDuD6qK+Mb1IZ12J fW50VNq0gnjhkBiksenvcJcKTqxjZVl368d6dgOW6M8MapB0KjHz+ObdE1g746MmW+5k +B1YjaMop1h3+WuviU2Y6YOoeYVIghczq9/L0GMuSudJEIMcm8JXz+/EEZDz2VSbLK2l P/5flZizRBgdEwlYNdGR0khIAguak+MuVOcftisPVXxU2aLkMMX8ihjYynLfIQbLYu4w 6uIw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789994193; x=1790598993; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=8SRT9W/2z9fLq6Pj3t4dd8eEawuNLFrl/C3bQijqfHo=; b=ghsJqk8i5xot3FUwXZK5vtfhpSGAaiW08Qh0AoDxUTq8j1+E1K6ngoOv63Mx/n1z1G CcnwcgjS/4sNVglAPn2/94P6RlofeZV6gVN9V5H8MFU7UjxXrlXmt53Gh3AryPTbJhJs FgF745Jh6pcgwMftLQlhCzvHARRO2+Ubl5F0pk3bseVMQ+DdhlD48VFne59FM+rHiiu5 YaGFnwuVGl8PJiX8PR7JVNSYKoHBEkiC3dizrxGkHLWPt4RF3bngjXx7uzlSfrY7wtZb aSAWD0UZL5ofdIPEyaS2OmhXSVkmTVRW/+hvQoquL7MISLhSPf/EDu5UIMkNZKQ1Wy1z rO+Q== X-Forwarded-Encrypted: i=1; AKwUvBw0AbCN0kpfrUbdYLzbnmdDfAKXszG3NzQveTTmTGRIazs9fIULW2CTGudVxCzNqLKCl7Ky3nbslXkF0gA=@vger.kernel.org X-Gm-Message-State: AFuF++m7xeFDovWdU7oA6pLOgH3r44OO8VLDADn2vCruXm3dnolMP8fP eZNJ6k53EZUxCOD/iflbZttftAce9iv7gE2EL+VzhfSN/k3+K4UifMzuxIWfqEI/or8= X-Gm-Gg: AYBFou3bgLrEAMqnHnL0HzZKug87Z37unc2kIDN41Emj4axwN33BEY6qc57k+Wl180k ePvMgjqrt2SF3ZShqjJIKagbunU31YgbcC0Z585GA6QrHMzl+q2gHr8APANAeyF5wMvajWIO74x v8A5zqmADZ9cKx2ZS9B1RFsvlW2mQNV+PcjKEwngrM5ejFhTelqZb/SBvzsywAxr8IVwO8ATfBG Xz0lZY2xTTNVqR3JHDCljrRL9CRMniFrI7rcEwc8NB0ir5UyIu7ZHhJxx5+Mw4hGDjbI/iixnrJ I8VNsZGac9HsFZsadwlTBUKFdh1el3H1kMp5p0fKnzo1iDGp1gQV63Y1wGsN/hm5Ur38td0op0Q 958hv3F8dLxfRpvz2II1FgMWbfzRGdEX6+SoDdI/8hQZHsur8b/HidDVpKbUZCbj/HDkVw6jkFq SLkjvaNppkDV2/RKkr4LKtRm+i32WU5Q4HEn/Rxc6T8MeimlHhV2C0gujFTf/LyeVMtz9eh9p6G 8dSAK1UOeCkCYfGVUS+lbq1cbGw9PimfI0= X-Received: by 2002:a05:600c:46cf:b0:49c:de80:b833 with SMTP id 5b1f17b1804b1-49fc5687b6cmr159289905e9.2.1789994192617; Mon, 21 Sep 2026 05:36:32 -0700 (PDT) Received: from ?IPV6:2a07:de40:8100:0:89a9:fd0e:583d:4a53? ([2001:af0:8000:1409:193:86:92:181]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48724460753sm23342442f8f.10.2026.09.21.05.36.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 21 Sep 2026 05:36:32 -0700 (PDT) Message-ID: <2b27bb4b-47e3-45ed-a26a-4b9de2b20542@suse.com> Date: Mon, 21 Sep 2026 14:36:30 +0200 Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 13/21] modpost: emit module descriptors as assembly To: "Lorenzo Stoakes (ARM)" Cc: Linus Torvalds , Nathan Chancellor , Nicolas Schier , Nick Desaulniers , Bill Wendling , Justin Stitt , Masahiro Yamada , Alexey Gladkov , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Arnd Bergmann , Catalin Marinas , Will Deacon , Mark Rutland , Ard Biesheuvel , Ilias Apalodimas , Josh Poimboeuf , Peter Zijlstra , Miguel Ojeda , Boqun Feng , Gary Guo , =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , =?UTF-8?Q?Onur_=C3=96zkan?= , Jonathan Corbet , Randy Dunlap , Kees Cook , "Gustavo A. R. Silva" , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-riscv@lists.infradead.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-efi@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-doc@vger.kernel.org, Jens Axboe , linux-hardening@vger.kernel.org References: <20260914-build-speedup-v2-0-39817ec5db23@kernel.org> <20260914-build-speedup-v2-13-39817ec5db23@kernel.org> <95baacfb-d8d9-4d2f-bc89-592df6f6f8e3@suse.com> Content-Language: en-US From: Petr Pavlu In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/21/26 1:57 PM, Lorenzo Stoakes (ARM) wrote: > (note there's a v3 see [0]) > > [0]: https://lore.kernel.org/linux-kbuild/20260917-build-speedup-v3-0-9ecf4163ff36@kernel.org/ Thanks, I missed it. > On Mon, Sep 21, 2026 at 01:25:09PM +0200, Petr Pavlu wrote: >> On 9/14/26 11:22 AM, Lorenzo Stoakes (ARM) wrote: >>> The sections were confirmed to be byte-for-byte identical to the C version >>> produced - each of .modinfo, .gnu.linkonce.this_module, __ksymtab*, >>> __ksymtab_strings, __kcrctab*, __kflagstab*, __versions, >>> __version_ext_crcs, __version_ext_names and their relocations - for all >>> 8,135 modules of a clang allmodconfig build with CONFIG_COMPILE_TEST off >>> and CONFIG_MODVERSIONS, CONFIG_EXTENDED_MODVERSIONS and >>> CONFIG_MODULE_SRCVERSION_ALL on, and for a sample built with gcc. >> >> Lowering the data to assembly loses debug information for __this_module, >> specifically that it has type `struct module`. It might be worth > > No, it keeps it - every module includes linux/module.h, and the extern > declaration of __this_module carries the type, so all of the stuff gdb > needs (e.g. ptype, p & field access), DWARF etc. is all there in the same > way as with .mod.c. > > Have confirmed locally. An extern declaration alone shouldn't cause its name and type to be included in debug information. They should appear only when the variable is referenced by some code. Testing with a simple module that previously referenced __this_module only in .mod.c and in no other file, such as lib/test_module.c, shows that the .ko no longer contains debug information for this variable. I've verified this behavior with GCC 16 and Clang 19. -- Cheers, Petr