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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 A8911C433FE for ; Tue, 8 Dec 2020 13:55:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7C6C0206DB for ; Tue, 8 Dec 2020 13:55:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729511AbgLHNzw (ORCPT ); Tue, 8 Dec 2020 08:55:52 -0500 Received: from mail.kernel.org ([198.145.29.99]:58018 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726338AbgLHNzw (ORCPT ); Tue, 8 Dec 2020 08:55:52 -0500 X-Gm-Message-State: AOAM531vd5GLJ17BIhllutjkE+6n48AniZDMzZN4ItSIvtDTIS7W8Z9L 5oWC82bBr16v2Ax/S/G/pXGTP2skjhWDLM+BhGQ= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1607435711; bh=aMUeJmcHjLR1mxPMY4lSg5wm08l9vr2Dq3J8KhZCHss=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=N6+VRiKj1w/sHG04FJYJajgruVEl0d0kXpByOymHxPthCNLPJiukFzJ0fV2Fks4F3 f3OYCjwUjrh0Mlf1Q4sJGjiuG+CSXHTbFZTkrqCv+RKCMWkLCdkoGeXDRPUxmeCutZ PvCcGNK3GKImyzLMtrB2yTw7+GoV0yDqsIR4dn7IMy5VKyojDA4DfYN2ZEygwOrw5h yf899Lyg8XrtlHlrasiYJQpQD5/jtisPkmLxhy3aBeoCxaov7xm4Im/ELWLRl42Ocw cizq88EGMi2nzasl/XChEgEAvqZzmNujCnkYUHPFgAM4zpJ9J9XBeHGGlR89vy8Yhi rTnMXtxRGJrBQ== X-Google-Smtp-Source: ABdhPJw84bKjNW6pc9lV2J+47WEe1njStGFQFPiO39biuyycOb/7NnBSKOzxngL0mEe4vYZqUHtN+LSV3ssbam6y5lc= X-Received: by 2002:a1c:b4c4:: with SMTP id d187mr3984205wmf.38.1607435710266; Tue, 08 Dec 2020 05:55:10 -0800 (PST) MIME-Version: 1.0 References: <20201201213707.541432-1-samitolvanen@google.com> In-Reply-To: From: Arnd Bergmann Date: Tue, 8 Dec 2020 14:54:28 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v8 00/16] Add support for Clang LTO To: Sami Tolvanen Cc: Masahiro Yamada , Steven Rostedt , Will Deacon , Josh Poimboeuf , Peter Zijlstra , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , Nick Desaulniers , clang-built-linux , Kernel Hardening , linux-arch , Linux ARM , Linux Kbuild mailing list , "linux-kernel@vger.kernel.org" , linux-pci Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Dec 8, 2020 at 1:15 PM Arnd Bergmann wrote: > On Tue, Dec 1, 2020 at 10:37 PM 'Sami Tolvanen' via Clang Built Linux wrote: > > - many builds complain about thousands of duplicate symbols in the kernel, e.g. > ld.lld: error: duplicate symbol: qrtr_endpoint_post > >>> defined in net/qrtr/qrtr.lto.o > >>> defined in net/qrtr/qrtr.o > ld.lld: error: duplicate symbol: init_module > >>> defined in crypto/842.lto.o > >>> defined in crypto/842.o > ld.lld: error: duplicate symbol: init_module > >>> defined in net/netfilter/nfnetlink_log.lto.o > >>> defined in net/netfilter/nfnetlink_log.o > ld.lld: error: duplicate symbol: vli_from_be64 > >>> defined in crypto/ecc.lto.o > >>> defined in crypto/ecc.o > ld.lld: error: duplicate symbol: __mod_of__plldig_clk_id_device_table > >>> defined in drivers/clk/clk-plldig.lto.o > >>> defined in drivers/clk/clk-plldig.o A small update here: I see this behavior with every single module build, including 'tinyconfig' with one module enabled, and 'defconfig'. I tuned the randconfig setting using KCONFIG_PROBABILITY=2:2:1 now, which only enables a few symbols. With this I see faster build times (obvioulsy), aroudn 30 seconds per kernel, and all small builds with CONFIG_MODULES disabled so far succeed. It appears that the problems I saw originally only happen for larger configurations, or possibly a combination of Kconfig options that don't happen that often on randconfig builds with low KCONFIG_PROBABILITY. Arnd