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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 27344C678D4 for ; Thu, 2 Mar 2023 07:58:22 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4PS3Pm4FR6z3cMx for ; Thu, 2 Mar 2023 18:58:20 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=rivosinc-com.20210112.gappssmtp.com header.i=@rivosinc-com.20210112.gappssmtp.com header.a=rsa-sha256 header.s=20210112 header.b=pn+DJn+k; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=rivosinc.com (client-ip=2a00:1450:4864:20::32f; helo=mail-wm1-x32f.google.com; envelope-from=alexghiti@rivosinc.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=rivosinc-com.20210112.gappssmtp.com header.i=@rivosinc-com.20210112.gappssmtp.com header.a=rsa-sha256 header.s=20210112 header.b=pn+DJn+k; dkim-atps=neutral Received: from mail-wm1-x32f.google.com (mail-wm1-x32f.google.com [IPv6:2a00:1450:4864:20::32f]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4PS3Nl4qswz3c2v for ; Thu, 2 Mar 2023 18:57:25 +1100 (AEDT) Received: by mail-wm1-x32f.google.com with SMTP id bg16-20020a05600c3c9000b003eb34e21bdfso1100957wmb.0 for ; Wed, 01 Mar 2023 23:57:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20210112.gappssmtp.com; s=20210112; t=1677743839; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=3gGlmdrxpk12L0HtiU5R9bJeUayhxQ74GXgfAq6meuw=; b=pn+DJn+k9uImMGeBMXuwnMQE1biMNzy71Plo8H7DOI3fKK/ceps9rgGUxc/bmw8s6L 4TQMSud9TXFc8/r2OEOEiAKv5SApxcJ1Yd/LQHA0imhiw3qi8hrsJYLIdS7LaNAmBH1O AbgLlGVWFn2hf8BkmR90At5+g3zqQ61Ankq9cGuBB9WgQfAsyn4JZulcRbW71gf7ZeYz oRP4F6/LxUTL9nxCbjnWUdwQSV0fTcnbx/sIcDMk8fB8xQ9dJ6UAQMnDD3HBbCn+Qr4a fIykdIwuX5WmEnYpwkBvfu6oXc7MDCcdwlfNYOa5JGNIdVdo8Hubuxh+Kfco99U7Z89i QfaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1677743839; 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=3gGlmdrxpk12L0HtiU5R9bJeUayhxQ74GXgfAq6meuw=; b=iiZByP2roH7UmBQ8MZ6LBmWMlOtXeKqTCn8P99Zp0tvQaNAZXHA/Oh2AepFYFPowii jpnQZL9feZP0jISWv4Wo1xjY1UgL0FwuEDtfDyjAr8x2tAuSwgU5Q2zjtNLXn13tsV1q VdmKUi3+ebJ/WFu24if4PT12SmB8CxzMa4rk93VBdLLEDPsESvZZn2OJLmNEgmqGCZbp su4lxSSG5QWCFkkUvJaPKt2uRpLDPmkhtnBmi6MNktHY0vVUd+iz4/m3RnOm6ERgwcCA eOo3qUjw4HmjEVfSpLvviuO2rRzSjCa8/tOxAL278Rc40yMWxyQRfUyHErkz0XTr297b vEKg== X-Gm-Message-State: AO0yUKVh5TeXiH0RYbLhuYDEPtK8EzNsWkLWLDFdLXT+ZiQMj8ssDRTy BR11LmIUDTQ8cyNS8qcYK/sDdawdPbGwRuHGVHJJ/w== X-Google-Smtp-Source: AK7set8WtHYe+gEo1Fgs1pSlJqsnM2tCvgsXzdB6/J3n+P8FnRw3jetc5Yrjj9TAlqQSjPmyeFZCYlu44lotg0az/Sk= X-Received: by 2002:a05:600c:4591:b0:3ea:8ed9:8e4b with SMTP id r17-20020a05600c459100b003ea8ed98e4bmr2655128wmo.6.1677743839531; Wed, 01 Mar 2023 23:57:19 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Alexandre Ghiti Date: Thu, 2 Mar 2023 08:57:08 +0100 Message-ID: Subject: Re: [PATCH v3 00/24] Remove COMMAND_LINE_SIZE from uapi To: Palmer Dabbelt Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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: dalias@libc.org, linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org, Catalin Marinas , dave.hansen@linux.intel.com, x86@kernel.org, linux-mips@vger.kernel.org, James.Bottomley@hansenpartnership.com, jcmvbkbc@gmail.com, hpa@zytor.com, sparclinux@vger.kernel.org, kernel@xen0n.name, Will Deacon , agordeev@linux.ibm.com, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, linux-snps-arc@lists.infradead.org, Arnd Bergmann , ysato@users.sourceforge.jp, corbet@lwn.net, linux-sh@vger.kernel.org, deller@gmx.de, chenhuacai@kernel.org, linux@armlinux.org.uk, mingo@redhat.com, geert@linux-m68k.org, vgupta@kernel.org, mattst88@gmail.com, borntraeger@linux.ibm.com, linux-xtensa@linux-xtensa.org, aou@eecs.berkeley.edu, gor@linux.ibm.com, hca@linux.ibm.com, Richard Henderson , npiggin@gmail.com, linux-m68k@lists.linux-m68k.org, ink@jurassic.park.msu.ru, loongarch@lists.linux.dev, Paul Walmsley , tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, chris@zankel.net, monstr@monstr.eu, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, svens@linux.ibm.com, linux-alpha@vger.kernel.org, bp@alien8.de, linuxppc-dev@lists.ozlabs.org, davem@davemloft.net Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Mar 2, 2023 at 4:17=E2=80=AFAM Palmer Dabbelt = wrote: > > On Tue, 14 Feb 2023 01:19:02 PST (-0800), hca@linux.ibm.com wrote: > > On Tue, Feb 14, 2023 at 09:58:17AM +0100, Geert Uytterhoeven wrote: > >> Hi Heiko, > >> > >> On Tue, Feb 14, 2023 at 9:39 AM Heiko Carstens wro= te: > >> > On Tue, Feb 14, 2023 at 08:49:01AM +0100, 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, b= ut > >> > > PowerPC increased it with a5980d064fe2 ("powerpc: Bump COMMAND_LIN= E_SIZE > >> > > to 2048"). There are also a handful of examples of COMMAND_LINE_S= IZE > >> > > increasing, but they're from before the UAPI split so I'm not quit= e sure > >> > > what that means: e5a6a1c90948 ("powerpc: derive COMMAND_LINE_SIZE = from > >> > > asm-generic"), 684d2fd48e71 ("[S390] kernel: Append scpdata to ker= nel > >> > > 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 b= een > >> > > part of the uapi to begin with, and userspace should be able to ha= ndle > >> > > /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 Goo= gle > >> > > search, but that's not really enough to consider it unused on my e= nd. > >> > > > >> > > The feedback on the v1 seemed to indicate that COMMAND_LINE_SIZE r= eally > >> > > shouldn't be part of uapi, so this now touches all the ports. I'v= e > >> > > tried to split this all out and leave it bisectable, but I haven't > >> > > tested it all that aggressively. > >> > > >> > Just to confirm this assumption a bit more: that's actually the same > >> > conclusion that we ended up with when commit 3da0243f906a ("s390: ma= ke > >> > command line configurable") went upstream. > > Thanks, I guess I'd missed that one. At some point I think there was > some discussion of making this a Kconfig for everyone, which seems > reasonable to me -- our use case for this being extended is syzkaller, > but we're sort of just picking a value that's big enough for now and > running with it. > > Probably best to get it out of uapi first, though, as that way at least > it's clear that it's not uABI. > > >> Commit 622021cd6c560ce7 ("s390: make command line configurable"), > >> I assume? > > > > Yes, sorry for that. I got distracted while writing and used the wrong > > branch to look this up. > > Alex: Probably worth adding that to the list in the cover letter as it > looks like you were planning on a v4 anyway (which I guess you now have > to do, given that I just added the issue to RISC-V). Yep, I will :) Thanks, Alex