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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1E703C7EE37 for ; Fri, 9 Jun 2023 06:51:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238108AbjFIGvO (ORCPT ); Fri, 9 Jun 2023 02:51:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55600 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229482AbjFIGvK (ORCPT ); Fri, 9 Jun 2023 02:51:10 -0400 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E0DA81BEB; Thu, 8 Jun 2023 23:51:02 -0700 (PDT) Received: from loongson.cn (unknown [113.200.148.30]) by gateway (Coremail) with SMTP id _____8BxrOrVy4JkcfAAAA--.2919S3; Fri, 09 Jun 2023 14:51:01 +0800 (CST) Received: from [10.130.0.149] (unknown [113.200.148.30]) by localhost.localdomain (Coremail) with SMTP id AQAAf8AxZuTSy4Jk8QsKAA--.30794S3; Fri, 09 Jun 2023 14:51:00 +0800 (CST) Subject: Re: [RFC PATCH] asm-generic: Unify uapi bitsperlong.h To: Arnd Bergmann References: <1683615903-10862-1-git-send-email-yangtiezhu@loongson.cn> <76d3be65-91df-7969-5303-38231a7df926@loongson.cn> Cc: Linux-Arch , linux-s390@vger.kernel.org, llvm@lists.linux.dev, linux-ia64@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-parisc@vger.kernel.org, x86@kernel.org, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, loongarch@lists.linux.dev, linux-alpha@vger.kernel.org, sparclinux@vger.kernel.org, linux-riscv@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org, loongson-kernel@lists.loongnix.cn From: Tiezhu Yang Message-ID: Date: Fri, 9 Jun 2023 14:50:58 +0800 User-Agent: Mozilla/5.0 (X11; Linux mips64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-CM-TRANSID: AQAAf8AxZuTSy4Jk8QsKAA--.30794S3 X-CM-SenderInfo: p1dqw3xlh2x3gn0dqz5rrqw2lrqou0/ X-Coremail-Antispam: 1Uk129KBj93XoW7Cr1UWFy8Kr1kJFy7Kr47KFX_yoW5JFyrpF 4UGF1j9r4kAr1fAFn2yw4jqa4Fyws7KF1aq3s0gryxJFs0gFyrtry29w4agFWqvr18Jr4j 93yUXFy5uay0yFXCm3ZEXasCq-sJn29KB7ZKAUJUUUUx529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUmlb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_JFI_Gr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVCY1x0267AK xVW8Jr0_Cr1UM2kKe7AKxVWUAVWUtwAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07 AIYIkI8VC2zVCFFI0UMc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWU AVWUtwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcVAKI4 8JM4IIrI8v6xkF7I0E8cxan2IY04v7Mxk0xIA0c2IEe2xFo4CEbIxvr21lc7CjxVAaw2AF wI0_JF0_Jw1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1l4IxYO2xFxV AFwI0_JF0_Jw1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2 zVAF1VAY17CE14v26r4a6rW5MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_JFI_Gr 1lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWU CwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCT nIWIevJa73UjIFyTuYvjxU7uc_DUUUU Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On 06/08/2023 08:56 PM, Arnd Bergmann wrote: > On Thu, Jun 8, 2023, at 09:04, Tiezhu Yang wrote: >> On 05/09/2023 05:37 PM, Arnd Bergmann wrote: >>> On Tue, May 9, 2023, at 09:05, Tiezhu Yang wrote: >>> >>> I think we are completely safe on the architectures that were >>> added since the linux-3.x days (arm64, riscv, csky, openrisc, >>> loongarch, nios2, and hexagon), but for the older ones there >>> is a regression risk. Especially on targets that are not that >>> actively maintained (sparc, alpha, ia64, sh, ...) there is >>> a good chance that users are stuck on ancient toolchains. >>> It's probably also a safe assumption that anyone with an older >>> libc version won't be using the latest kernel headers, so >>> I think we can still do this across architectures if both >>> glibc and musl already require a compiler that is new enough, >>> or alternatively if we know that the kernel headers require >>> a new compiler for other reasons and nobody has complained. >>> >>> For glibc, it looks the minimum compiler version was raised >>> from gcc-5 to gcc-8 four years ago, so we should be fine. >>> >>> In musl, the documentation states that at least gcc-3.4 or >>> clang-3.2 are required, which probably predate the >>> __SIZEOF_LONG__ macro. On the other hand, musl was only >>> released in 2011, and building musl itself explicitly >>> does not require kernel uapi headers, so this may not >>> be too critical. >>> >>> There is also uClibc, but I could not find any minimum >>> supported compiler version for that. Most commonly, this >>> one is used for cross-build environments, so it's also >>> less likely to have libc/gcc/headers being wildly out of >>> sync. Not sure. >>> >>> Arnd >>> >>> [1] https://sourceware.org/pipermail/libc-alpha/2019-January/101010.html >>> >> >> Thanks Arnd for the detailed reply. >> Any more comments? What should I do in the next step? > > I think the summary is "it's probably fine", but I don't know > for sure, and it may not be worth the benefit. Thank you, it is very clear now. > Maybe you can prepare a v2 that only does this for the newer > architectures I mentioned above, with and an explanation and > link to my above reply in the file comments? Only arm64, riscv and loongarch belong to the newer architectures which are related with this change, I am not sure it is necessary to "unify" uapi bitsperlong.h for them. Anyway, let me try, I will send a new version, maybe this is going to progress in the right direction. Thanks, Tiezhu