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 C6DAFC7EE33 for ; Thu, 2 Mar 2023 10:10:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229660AbjCBKKA (ORCPT ); Thu, 2 Mar 2023 05:10:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229511AbjCBKJp (ORCPT ); Thu, 2 Mar 2023 05:09:45 -0500 Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::223]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BBD1911EB3; Thu, 2 Mar 2023 02:09:42 -0800 (PST) Received: (Authenticated sender: alex@ghiti.fr) by mail.gandi.net (Postfix) with ESMTPSA id 0EC1E60002; Thu, 2 Mar 2023 10:09:27 +0000 (UTC) Message-ID: Date: Thu, 2 Mar 2023 11:09:27 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Subject: Re: [PATCH v4 00/24] Remove COMMAND_LINE_SIZE from uapi Content-Language: en-US To: Geert Uytterhoeven , 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 References: <20230302093539.372962-1-alexghiti@rivosinc.com> From: Alexandre Ghiti In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Geert, On 3/2/23 10:47, Geert Uytterhoeven wrote: > 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? I do not know, should I? Palmer did all the work, I only fixed 3 minor things > > 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