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 X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 214AAC10F13 for ; Thu, 11 Apr 2019 18:15:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DED7E2084D for ; Thu, 11 Apr 2019 18:15:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555006541; bh=CYpuz4kSFGt3ReVvAdShqeumca74RVzqor2qC337P/w=; h=From:Subject:To:Cc:References:Date:In-Reply-To:List-ID:From; b=Z8imuSKOImKHWU65tSfWX74kBI5oyZlSz6A/0qDPgUlInERhFUAU64X2FCkNJ/PCH zwk4VnAM77My6k0siFYCyavkCLILTTaCsKebKqJbYx5o9ULOQaeIsIYPp4RezQzss+ vDd8B3Nn0ZYWAfuhQlgT2y1upmNJ3XPPkZyjl7KI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726705AbfDKSPj (ORCPT ); Thu, 11 Apr 2019 14:15:39 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:33414 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726538AbfDKSPj (ORCPT ); Thu, 11 Apr 2019 14:15:39 -0400 Received: by mail-qt1-f193.google.com with SMTP id k14so8289841qtb.0 for ; Thu, 11 Apr 2019 11:15:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:subject:to:cc:references:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=TVgurs4GiZUYMCyRAOgHBG6ClH9hAVLK6w8uzS9DNis=; b=GEc2j/2xhzfpicBPi6SMEwiPnM45uwzCZqrp+AOKZ7AMieV+rFT5hinylJbaZFZOb8 h9rCaGy4khD2r/4TbZ3vLJya5tY+hW6mxg8dYwyG+7ZRtk3LxaSyofZkXdguuTQlD793 nj+yPRtAJc3RdSHLWh4i2cmw/jQHZEqHXhFEKyRZfwQ/kyAWPLkcWI4fJjIrrmOpelXF Cj0Wa6LvgfBM6Yg1ccXg09utXzNrqBAVgVf1yJJC34DyCW+vSAq6qvgEas9rPqkgS5X6 FKVqULURWjRl8z9cnHDo9kkG+rqLPZ8zoZLLMJ/r71PawPghB/vW3QLNtcHNuij0acVb sEMg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:subject:to:cc:references:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=TVgurs4GiZUYMCyRAOgHBG6ClH9hAVLK6w8uzS9DNis=; b=PL5ZK3bgx6aV01z2Cu6lbCA0erPUAT27LqGXjrm5Ct/tIEfDbGdSk6h2R97ZTB/Um/ g8xx6nkSohj8U/pdjjmbu6DF0ElmZ+LSuhFWvwFkHmR+ANNwuEivu+S847Y5DYBoWHmd PU/NKmIoLwlUdLcDuIwoKPdiTI/vQOCYdG7GtkFo3LWy41ACUXB9KofPP0nxHKOWCvzs AjhChIRX9k4bgFuuwy4TqVGnsumiUlaBf5XFjcNp+0ofR+a3D8veSs3V1+nTHM46pLtW 5GRm6n+gUWFhmrZ/rNnA4hmSXXASFmCL52S/l2F3LmMGaEbrTKCPX7jB3uHPMG+Xp4CR /DgQ== X-Gm-Message-State: APjAAAWZv0pXe3ngtf3k0lTF2G7tWIIh/d2adwQevNHzQ737A1MuYL2G 42JQfZcGZVZBegaerPcb5NM= X-Google-Smtp-Source: APXvYqzv1rCPsXgrZWzmBNIPeGDVdFr+SIcu6khPUQQ/uF4OUThORkd6rdqfcP4l4a1aKNmfpWmjDQ== X-Received: by 2002:ac8:2246:: with SMTP id p6mr42032186qtp.225.1555006538066; Thu, 11 Apr 2019 11:15:38 -0700 (PDT) Received: from [10.84.150.23] ([167.220.149.23]) by smtp.gmail.com with ESMTPSA id v58sm25999568qtv.66.2019.04.11.11.15.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 11 Apr 2019 11:15:37 -0700 (PDT) From: Sinan Kaya X-Google-Original-From: Sinan Kaya Subject: Re: [PATCH v3] init: Do not select DEBUG_KERNEL by default To: Masahiro Yamada Cc: Linux Kernel Mailing List , Josh Triplett , Kees Cook , Andrew Morton , "Peter Zijlstra (Intel)" , Johannes Weiner , Nicholas Piggin , Mathieu Desnoyers , Vasily Gorbik , Adrian Reber , Richard Guy Briggs , Andy Shevchenko , Petr Mladek , Joe Lawrence , Matthew Wilcox , Randy Dunlap , Mikulas Patocka , Robin Murphy , Tetsuo Handa , Changbin Du References: <20190411005634.8495-1-okaya@kernel.org> Message-ID: Date: Thu, 11 Apr 2019 14:15:36 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/11/2019 1:48 AM, Masahiro Yamada wrote: >> I was going by what Kconfig tells me >> >> Symbol: KALLSYMS_ALL [=n] >> Depends on: DEBUG_KERNEL [=n] && KALLSYMS [=y] > Lots of features have 'depends on DEBUG_KERNEL'. > What is special about KALLSYMS_ALL here? I had to do some learning about KALLSYSM_ALL. Based on my limited searching, KALLSYMS_ALL allows you to locate the symbol location at runtime from the kernel. Without KALLSYM_ALL, you can only locate the kernel code only. With KALLSYMS_ALL, you can locate the symbols for any data structure including kernel modules. I'm not a KALLSYMS person but based on my search, I'd consider KALLSYMS_ALL a debug feature as it is today. kernel/kallsyms.c: else if (IS_ENABLED(CONFIG_KALLSYMS_ALL)) kernel/livepatch/Kconfig: depends on KALLSYMS_ALL kernel/module.c:#ifdef CONFIG_KALLSYMS_ALL kernel/module.c:#ifndef CONFIG_KALLSYMS_ALL lib/Kconfig.debug: select KALLSYMS_ALL config LOCKDEP bool depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT select KALLSYMS select KALLSYMS_ALL lib/Kconfig.debug: select KALLSYMS_ALL config LATENCYTOP bool "Latency measuring infrastructure" select KALLSYMS select KALLSYMS_ALL scripts/link-vmlinux.sh: if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then