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=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 9144EC43460 for ; Tue, 4 May 2021 13:25:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 733B2611AE for ; Tue, 4 May 2021 13:25:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231237AbhEDN0W (ORCPT ); Tue, 4 May 2021 09:26:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231144AbhEDN0V (ORCPT ); Tue, 4 May 2021 09:26:21 -0400 Received: from mail-pg1-x52d.google.com (mail-pg1-x52d.google.com [IPv6:2607:f8b0:4864:20::52d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 49F46C061574; Tue, 4 May 2021 06:25:26 -0700 (PDT) Received: by mail-pg1-x52d.google.com with SMTP id d10so6866392pgf.12; Tue, 04 May 2021 06:25:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=6Usua23eG7jeiBMRqPk961Vu0oHy/tcPvUmAPfGsd3M=; b=sTsLRdnna2sWw8Z9FaRNxSMft/pBwo/y8kKHX5A/bs3GC09QaDMsRY3ukXdyuzno5K TTskFLmfiBewHvymg8gVK4V/TVKfQ23eP/Tu218+y4OC9ZktHTTfkJaMdWa7vEwWHVHf VxYQ8k02YYjFMfqJEehpLYDZNE6BW1NlQEESuSmZ810jAvl03Y3YtDZxi0VRPLFBXUYJ uFkEjyscASDsMyBzUlSN2YID8zDZop12wU5y2YkeCcPz8pkVx3zQ8M+7EstrM8ejVLtl +UOwsKs2q6eecp6bytsFx6j4sQe81qn14UFJkgvj+14FZVfWqRencBKKh1p/ACnYmBNR rY6g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=6Usua23eG7jeiBMRqPk961Vu0oHy/tcPvUmAPfGsd3M=; b=j3Hg6m5oaYGEZsgYqRwl++qN4JIXMTMXJtHolRD1lP6PCclIOpVygU1zRVna11z+IO x+iWaSQLK/nfeTGFb92MLQUcvfWOh2YlPMLWWK60qBb8YSOXYcp9MA7AUWU0nxO4t52L Fj8WzXKujlneWcmCclOrGBYBTRQMCVN34qgXCUu75uG+UlReNTFMepiLWLSqxnH8tPYS Hf2GglOehP62hl7SSeAOVXFaiZofddgsmt+vBZ63qcufIQeUOFTI7G96FEVMLfNgO4v/ YdJXqaEGIKTYOFzfyRADXqJVjpnHqoEKd/US+ZgwyaWW5zvLuLZr2LZ5HXwYUxiCPpeQ VXGg== X-Gm-Message-State: AOAM530VnOf37L1srkA+DV3EisywCUX8GR0KN8aSL4BbqZMcMJPsQjXo GbXVztJDSITP7CglaGP20rnORD6GcAk/i7jL7ng= X-Google-Smtp-Source: ABdhPJzvGspK5lFxakG5qrtBG+U2cTV9ewqHbVPwR6w2Q0rRyLr2DmXQST3reCaT/EdEu09iSl/HelPXit3utm0fpRE= X-Received: by 2002:a17:90a:d90c:: with SMTP id c12mr5218252pjv.129.1620134725780; Tue, 04 May 2021 06:25:25 -0700 (PDT) MIME-Version: 1.0 References: <20210501151538.145449-1-masahiroy@kernel.org> <3943bc020f6227c8801907317fc113aa13ad4bad.camel@perches.com> <20210502183030.GF10366@gate.crashing.org> <81a926a3bdb70debe3ae2b13655ea8d249fb9991.camel@perches.com> <20210502203253.GH10366@gate.crashing.org> <20210502223007.GZ1847222@casper.infradead.org> In-Reply-To: From: Andy Shevchenko Date: Tue, 4 May 2021 16:25:09 +0300 Message-ID: Subject: Re: [PATCH] Raise the minimum GCC version to 5.2 To: Arnd Bergmann Cc: Matthew Wilcox , Linus Torvalds , Segher Boessenkool , Joe Perches , Miguel Ojeda , Masahiro Yamada , Albert Ou , Linux Kbuild mailing list , Greg Kroah-Hartman , Jonathan Corbet , Linux Doc Mailing List , linux-kernel , Palmer Dabbelt , Paul Walmsley , Catalin Marinas , Miguel Ojeda , Paul Mackerras , linux-riscv , linuxppc-dev , Will Deacon , Linux ARM Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 3, 2021 at 12:29 PM Arnd Bergmann wrote: > > On Mon, May 3, 2021 at 9:35 AM Alexander Dahl wrote: > > > > Desktops and servers are all nice, however I just want to make you > > aware, there are embedded users forced to stick to older cross > > toolchains for different reasons as well, e.g. in industrial > > environment. :-) > > > > This is no show stopper for us, I just wanted to let you be aware. > > Can you be more specific about what scenarios you are thinking of, > what the motivations are for using an old compiler with a new kernel > on embedded systems, and what you think a realistic maximum > time would be between compiler updates? > > One scenario that I've seen previously is where user space and > kernel are built together as a source based distribution (OE, buildroot, > openwrt, ...), and the compiler is picked to match the original sources > of the user space because that is best tested, but the same compiler > then gets used to build the kernel as well because that is the default > in the build environment. > > There are two problems I see with this logic: > > - Running the latest kernel to avoid security problems is of course > a good idea, but if one runs that with ten year old user space that > is never updated, the system is likely to end up just as insecure. > Not all bugs are in the kernel. > > - The same logic that applies to ancient user space staying with > an ancient compiler (it's better tested in this combination) also > applies to the kernel: running the latest kernel on an old compiler > is something that few people test, and tends to run into more bugs > than using the compiler that other developers used to test that > kernel. I understand that you are talking about embedded, but it you stuck with a distro (esp. LTS one, like CentOS 7.x), you have gcc 4.8.5 there for everything, but they have got security updates. Seems if you are with a distro you have to stick with its kernel with all pros and cons of such an approach. -- With Best Regards, Andy Shevchenko 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=-0.8 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 D79EDC433B4 for ; Tue, 4 May 2021 13:25:44 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5B423611AE for ; Tue, 4 May 2021 13:25:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5B423611AE Authentication-Results: mail.kernel.org; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Mon, May 3, 2021 at 12:29 PM Arnd Bergmann wrote: > > On Mon, May 3, 2021 at 9:35 AM Alexander Dahl wrote: > > > > Desktops and servers are all nice, however I just want to make you > > aware, there are embedded users forced to stick to older cross > > toolchains for different reasons as well, e.g. in industrial > > environment. :-) > > > > This is no show stopper for us, I just wanted to let you be aware. > > Can you be more specific about what scenarios you are thinking of, > what the motivations are for using an old compiler with a new kernel > on embedded systems, and what you think a realistic maximum > time would be between compiler updates? > > One scenario that I've seen previously is where user space and > kernel are built together as a source based distribution (OE, buildroot, > openwrt, ...), and the compiler is picked to match the original sources > of the user space because that is best tested, but the same compiler > then gets used to build the kernel as well because that is the default > in the build environment. > > There are two problems I see with this logic: > > - Running the latest kernel to avoid security problems is of course > a good idea, but if one runs that with ten year old user space that > is never updated, the system is likely to end up just as insecure. > Not all bugs are in the kernel. > > - The same logic that applies to ancient user space staying with > an ancient compiler (it's better tested in this combination) also > applies to the kernel: running the latest kernel on an old compiler > is something that few people test, and tends to run into more bugs > than using the compiler that other developers used to test that > kernel. I understand that you are talking about embedded, but it you stuck with a distro (esp. LTS one, like CentOS 7.x), you have gcc 4.8.5 there for everything, but they have got security updates. Seems if you are with a distro you have to stick with its kernel with all pros and cons of such an approach. -- With Best Regards, Andy Shevchenko _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv 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=-0.6 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 1E310C433B4 for ; Tue, 4 May 2021 13:26:02 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9F630613C6 for ; 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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=6Usua23eG7jeiBMRqPk961Vu0oHy/tcPvUmAPfGsd3M=; b=XZB6mIbK1QkV/d89XOhJWT3Rx//v5GFojpvnbFAlJCZy1Kh3P5zXTqoPmwdk06AOpc Vex9FJXIziuO0TkjmcRfqDwgbxFAvB98YY8rCoFDRzNoeB5DOBRi1dGl0Wn3ylJqBJFL W6cbsqd2c2tU5F0eyb4oAN02P9lkwomkt6iUMzPLPVo+VEFJfwiOF3cErKBG5qPw5bh5 EP++KmrQkbkty9RDZA5ZWVeFqcHvqyt6fAmK6DVIpNs/IqGOlhu2kAGRW7Gj9D4dSwkT 2OqUOKt9YFQ/vy2Z0+yn79z1akePwe7jQaOoDEiQTNdLOXiZ8MODU2A397LT6ybD06nI MWig== X-Gm-Message-State: AOAM530hzZtcCNMRA3ohMyAfXu7ZsoRnhKW4bMInL+Nd63qyaO7Gft0d WvFiN1aQYSk3PYpFdS+2YpWmvqUj7Y0/rZGUDA5cnjhhoio= X-Google-Smtp-Source: ABdhPJzvGspK5lFxakG5qrtBG+U2cTV9ewqHbVPwR6w2Q0rRyLr2DmXQST3reCaT/EdEu09iSl/HelPXit3utm0fpRE= X-Received: by 2002:a17:90a:d90c:: with SMTP id c12mr5218252pjv.129.1620134725780; Tue, 04 May 2021 06:25:25 -0700 (PDT) MIME-Version: 1.0 References: <20210501151538.145449-1-masahiroy@kernel.org> <3943bc020f6227c8801907317fc113aa13ad4bad.camel@perches.com> <20210502183030.GF10366@gate.crashing.org> <81a926a3bdb70debe3ae2b13655ea8d249fb9991.camel@perches.com> <20210502203253.GH10366@gate.crashing.org> <20210502223007.GZ1847222@casper.infradead.org> In-Reply-To: From: Andy Shevchenko Date: Tue, 4 May 2021 16:25:09 +0300 Message-ID: Subject: Re: [PATCH] Raise the minimum GCC version to 5.2 To: Arnd Bergmann Content-Type: text/plain; charset="UTF-8" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Albert Ou , Catalin Marinas , Linux Kbuild mailing list , Greg Kroah-Hartman , Masahiro Yamada , Jonathan Corbet , Linux Doc Mailing List , linux-kernel , Matthew Wilcox , Miguel Ojeda , Will Deacon , Palmer Dabbelt , Paul Walmsley , Joe Perches , Paul Mackerras , linux-riscv , Miguel Ojeda , Linus Torvalds , Linux ARM , linuxppc-dev Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, May 3, 2021 at 12:29 PM Arnd Bergmann wrote: > > On Mon, May 3, 2021 at 9:35 AM Alexander Dahl wrote: > > > > Desktops and servers are all nice, however I just want to make you > > aware, there are embedded users forced to stick to older cross > > toolchains for different reasons as well, e.g. in industrial > > environment. :-) > > > > This is no show stopper for us, I just wanted to let you be aware. > > Can you be more specific about what scenarios you are thinking of, > what the motivations are for using an old compiler with a new kernel > on embedded systems, and what you think a realistic maximum > time would be between compiler updates? > > One scenario that I've seen previously is where user space and > kernel are built together as a source based distribution (OE, buildroot, > openwrt, ...), and the compiler is picked to match the original sources > of the user space because that is best tested, but the same compiler > then gets used to build the kernel as well because that is the default > in the build environment. > > There are two problems I see with this logic: > > - Running the latest kernel to avoid security problems is of course > a good idea, but if one runs that with ten year old user space that > is never updated, the system is likely to end up just as insecure. > Not all bugs are in the kernel. > > - The same logic that applies to ancient user space staying with > an ancient compiler (it's better tested in this combination) also > applies to the kernel: running the latest kernel on an old compiler > is something that few people test, and tends to run into more bugs > than using the compiler that other developers used to test that > kernel. I understand that you are talking about embedded, but it you stuck with a distro (esp. LTS one, like CentOS 7.x), you have gcc 4.8.5 there for everything, but they have got security updates. Seems if you are with a distro you have to stick with its kernel with all pros and cons of such an approach. -- With Best Regards, Andy Shevchenko 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=-0.8 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 5F3EDC433B4 for ; Tue, 4 May 2021 13:27:11 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CFE17611AE for ; Tue, 4 May 2021 13:27:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CFE17611AE Authentication-Results: mail.kernel.org; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, May 3, 2021 at 12:29 PM Arnd Bergmann wrote: > > On Mon, May 3, 2021 at 9:35 AM Alexander Dahl wrote: > > > > Desktops and servers are all nice, however I just want to make you > > aware, there are embedded users forced to stick to older cross > > toolchains for different reasons as well, e.g. in industrial > > environment. :-) > > > > This is no show stopper for us, I just wanted to let you be aware. > > Can you be more specific about what scenarios you are thinking of, > what the motivations are for using an old compiler with a new kernel > on embedded systems, and what you think a realistic maximum > time would be between compiler updates? > > One scenario that I've seen previously is where user space and > kernel are built together as a source based distribution (OE, buildroot, > openwrt, ...), and the compiler is picked to match the original sources > of the user space because that is best tested, but the same compiler > then gets used to build the kernel as well because that is the default > in the build environment. > > There are two problems I see with this logic: > > - Running the latest kernel to avoid security problems is of course > a good idea, but if one runs that with ten year old user space that > is never updated, the system is likely to end up just as insecure. > Not all bugs are in the kernel. > > - The same logic that applies to ancient user space staying with > an ancient compiler (it's better tested in this combination) also > applies to the kernel: running the latest kernel on an old compiler > is something that few people test, and tends to run into more bugs > than using the compiler that other developers used to test that > kernel. I understand that you are talking about embedded, but it you stuck with a distro (esp. LTS one, like CentOS 7.x), you have gcc 4.8.5 there for everything, but they have got security updates. Seems if you are with a distro you have to stick with its kernel with all pros and cons of such an approach. -- With Best Regards, Andy Shevchenko _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel