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 BC030C678D4 for ; Thu, 2 Mar 2023 09:48:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230072AbjCBJsR convert rfc822-to-8bit (ORCPT ); Thu, 2 Mar 2023 04:48:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57374 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229649AbjCBJsP (ORCPT ); Thu, 2 Mar 2023 04:48:15 -0500 Received: from mail-qt1-f176.google.com (mail-qt1-f176.google.com [209.85.160.176]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 764E71BAD6 for ; Thu, 2 Mar 2023 01:48:04 -0800 (PST) Received: by mail-qt1-f176.google.com with SMTP id y10so12699110qtj.2 for ; Thu, 02 Mar 2023 01:48:04 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=SFYMa4F5zx6QmdN+xdk9xuKBVfUQIkEC+rLl+xVi7rY=; b=2wXcW8maWDZJijtig1iO9w7okTaX2/cZ9K49XftpyJRhcIWkg8Binu2lesxyay4Y+X YtG4gGZpFXizQ97EX4u9xlUZoLjkr93xQ6iFmlROvMWGZJISSs18JHl4xgBqPXQTlcVu WLbwQEtJPEg997Geht9ZKhF8xYTgQ3dgEVxhy7FhyxoFdGT38XRCZPp4fJCltpCqDLRI G720Hz5WqURsfE3YzQmGZ6Ha9owQzpCyjPVuTeP63G8dF6pW7p3H9IMzvo4clO1XK+OB fV0mpw/obxbs8kjoVcpjxpbOzCCt36htsKqmKAPWJ9YpTKyFa2FPDMatiSxuqJI609pC apOw== X-Gm-Message-State: AO0yUKVxOSWYN0fbGGM3FrRXlXglOXm/2WZdgYuAvDeY9HUIePrFw3ne OBj7TOEUnck0x0nKfAmsXHsVHqESnQdsqQ== X-Google-Smtp-Source: AK7set8Tkj6vUyRFxnKHGCrQmrBKlTtYJPFgC1W0IZ0//Y/rh4eaWItyt5Fcj7N9dpMbBohF3jz7PA== X-Received: by 2002:a05:622a:1882:b0:3b6:8b52:1359 with SMTP id v2-20020a05622a188200b003b68b521359mr2746531qtc.0.1677750483106; Thu, 02 Mar 2023 01:48:03 -0800 (PST) Received: from mail-qv1-f53.google.com (mail-qv1-f53.google.com. [209.85.219.53]) by smtp.gmail.com with ESMTPSA id q18-20020ac87352000000b003bfaff2a6b9sm9977626qtp.10.2023.03.02.01.48.02 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 02 Mar 2023 01:48:02 -0800 (PST) Received: by mail-qv1-f53.google.com with SMTP id y12so11235915qvt.8 for ; Thu, 02 Mar 2023 01:48:02 -0800 (PST) X-Received: by 2002:a81:ad43:0:b0:533:91d2:9d94 with SMTP id l3-20020a81ad43000000b0053391d29d94mr5972312ywk.5.1677750462713; Thu, 02 Mar 2023 01:47:42 -0800 (PST) MIME-Version: 1.0 References: <20230302093539.372962-1-alexghiti@rivosinc.com> In-Reply-To: <20230302093539.372962-1-alexghiti@rivosinc.com> From: Geert Uytterhoeven Date: Thu, 2 Mar 2023 10:47:31 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v4 00/24] Remove COMMAND_LINE_SIZE from uapi To: Alexandre Ghiti Cc: Jonathan Corbet , Richard Henderson , Ivan Kokshaysky , Matt Turner , Vineet Gupta , Russell King , Catalin Marinas , Will Deacon , Huacai Chen , WANG Xuerui , Michal Simek , Thomas Bogendoerfer , "James E . J . Bottomley" , Helge Deller , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Paul Walmsley , Palmer Dabbelt , Albert Ou , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Yoshinori Sato , Rich Felker , "David S . Miller" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , Chris Zankel , Max Filippov , Arnd Bergmann , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, loongarch@lists.linux.dev, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-m68k@vger.kernel.org Hi Alex, On Thu, Mar 2, 2023 at 10:35 AM Alexandre Ghiti wrote: > This all came up in the context of increasing COMMAND_LINE_SIZE in the > RISC-V port. In theory that's a UABI break, as COMMAND_LINE_SIZE is the > maximum length of /proc/cmdline and userspace could staticly rely on > that to be correct. > > Usually I wouldn't mess around with changing this sort of thing, but > PowerPC increased it with a5980d064fe2 ("powerpc: Bump COMMAND_LINE_SIZE > to 2048"). There are also a handful of examples of COMMAND_LINE_SIZE > increasing, but they're from before the UAPI split so I'm not quite sure > what that means: e5a6a1c90948 ("powerpc: derive COMMAND_LINE_SIZE from > asm-generic"), 684d2fd48e71 ("[S390] kernel: Append scpdata to kernel > boot command line"), 22242681cff5 ("MIPS: Extend COMMAND_LINE_SIZE"), > and 2b74b85693c7 ("sh: Derive COMMAND_LINE_SIZE from > asm-generic/setup.h."). > > It seems to me like COMMAND_LINE_SIZE really just shouldn't have been > part of the uapi to begin with, and userspace should be able to handle > /proc/cmdline of whatever length it turns out to be. I don't see any > references to COMMAND_LINE_SIZE anywhere but Linux via a quick Google > search, but that's not really enough to consider it unused on my end. > > This issue was already considered in s390 and they reached the same > conclusion in commit 622021cd6c56 ("s390: make command line > configurable"). > > The feedback on the v1 seemed to indicate that COMMAND_LINE_SIZE really > shouldn't be part of uapi, so this now touches all the ports. I've > tried to split this all out and leave it bisectable, but I haven't > tested it all that aggressively. > > Changes since v3 : > * Added RB/AB > * Added a mention to commit 622021cd6c56 ("s390: make command line > configurable") in the cover letter Thanks for the update! Apparently you forgot to add your own SoB? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds