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 7E3F8C6FD1D for ; Thu, 30 Mar 2023 16:40:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232063AbjC3Qkt (ORCPT ); Thu, 30 Mar 2023 12:40:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232097AbjC3Qkr (ORCPT ); Thu, 30 Mar 2023 12:40:47 -0400 Received: from mail-wm1-x335.google.com (mail-wm1-x335.google.com [IPv6:2a00:1450:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80F61CC2D for ; Thu, 30 Mar 2023 09:40:45 -0700 (PDT) Received: by mail-wm1-x335.google.com with SMTP id j36-20020a05600c1c2400b003f04057c152so63860wms.5 for ; Thu, 30 Mar 2023 09:40:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1680194444; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=kz/2H/BTIuKLAKXpo3BrU6LM5Cbhbn/nr7Y/43JgHBo=; b=ZlHh9rnbOioBf3nV/3JYjFE5Qh/bXo4StWdfNEsfuVogmTWridktEfoOhrvWpVNNhE 0z/X0MYaJjK/QYT4ITLVIUdplXX/DuXksJC0IpeVKtHOrPLMJe9eSvHXtK4aOFvf4tZs /AbEoXyA7m4P/L9dHHblxxWiEqpMvlOY5GomHTzf+A7mUydBq8mvV4Xac+jQ3DUw+m7d M7bxCvgbaGFMHEPdtiAa6ky4qk4LVn0KlYFTszccyx+U9QZE1gLR26fPAJN9gaLHkJpX WQORjeI04LW5T5Q3kvDg17MPl5M4+c/QRypn5gBwOkQH/rvgvQ4KM27LU9sBhn9IdM+7 8UVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680194444; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=kz/2H/BTIuKLAKXpo3BrU6LM5Cbhbn/nr7Y/43JgHBo=; b=u2dBjPhChyl39f4jsiLCH/yDi2TQrVtdn+iPahe1REs/3m4ZhnI9T97rw4MhUhqHzj J/23JwHQnEpwwVy6V7TUf6yiTaauVCvSzl129yxKMbQ8A3dYBVYsXoogjOGh3H05ctrZ g+Y4mzihHdW/P8i2j1py9WBwHgP0dNbWl2UtJSuBxcRu9A2C1ztNxkznWDXGaxvdtRGb E76jXMn+2VCIdoAmGEuthjsIJXp7IlUWDYpAB19h7/zK42ocfq9ut7s/PS0O2HH4u5y3 l0fukS0uIhm8qfytSieEHW7U3O9BNCV+ImLdy8pnK98QymA0d26IpXPP5XjOfIildZVb NKgw== X-Gm-Message-State: AO0yUKUS512TliSeRaXuSRs4AYHzd1RtRgpVFtRa73qWuB4TEu0HbJaX NQEKF1jyTCP3f2CHYuC/5irfAQ== X-Google-Smtp-Source: AK7set+T5+LX8G1drB7duDYdeQf04Abk5u9lOdEbqBzlttJPRn/c1AIIE43phBoZUQBtKJJiVWYC7Q== X-Received: by 2002:a7b:c8d0:0:b0:3eb:39e7:35fe with SMTP id f16-20020a7bc8d0000000b003eb39e735femr17905942wml.30.1680194443891; Thu, 30 Mar 2023 09:40:43 -0700 (PDT) Received: from [172.20.10.2] ([37.166.66.243]) by smtp.gmail.com with ESMTPSA id w20-20020a05600c475400b003f034c76e85sm3545852wmo.38.2023.03.30.09.40.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Mar 2023 09:40:43 -0700 (PDT) Message-ID: Date: Thu, 30 Mar 2023 18:40:39 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH 18/21] ARM: drop SMP support for ARM11MPCore Content-Language: en-GB To: Arnd Bergmann , Arnd Bergmann , linux-kernel@vger.kernel.org Cc: Vineet Gupta , Russell King , Linus Walleij , Catalin Marinas , Will Deacon , guoren , Brian Cain , Geert Uytterhoeven , Michal Simek , Thomas Bogendoerfer , Dinh Nguyen , Stafford Horne , Helge Deller , Michael Ellerman , Christophe Leroy , Paul Walmsley , Palmer Dabbelt , Rich Felker , John Paul Adrian Glaubitz , "David S . Miller" , Max Filippov , Christoph Hellwig , Robin Murphy , "Lad, Prabhakar" , "Conor.Dooley" , linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, "linux-oxnas@groups.io" , "linux-csky@vger.kernel.org" , linux-hexagon@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, "linux-openrisc@vger.kernel.org" , linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, Daniel Golle References: <20230327121317.4081816-1-arnd@kernel.org> <20230327121317.4081816-19-arnd@kernel.org> <6a5bd3a3-87e0-4a24-89ca-d265b0817a95@app.fastmail.com> From: Neil Armstrong In-Reply-To: <6a5bd3a3-87e0-4a24-89ca-d265b0817a95@app.fastmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org Le 30/03/2023 à 12:03, Arnd Bergmann a écrit : > On Thu, Mar 30, 2023, at 09:48, Neil Armstrong wrote: >> On 27/03/2023 14:13, Arnd Bergmann wrote: >>> From: Arnd Bergmann >>> >>> The cache management operations for noncoherent DMA on ARMv6 work >>> in two different ways: >>> >>> * When CONFIG_DMA_CACHE_RWFO is set, speculative prefetches on in-flight >>> DMA buffers lead to data corruption when the prefetched data is written >>> back on top of data from the device. >>> >>> * When CONFIG_DMA_CACHE_RWFO is disabled, a cache flush on one CPU >>> is not seen by the other core(s), leading to inconsistent contents >>> accross the system. >>> >>> As a consequence, neither configuration is actually safe to use in a >>> general-purpose kernel that is used on both MPCore systems and ARM1176 >>> with prefetching enabled. >>> >>> We could add further workarounds to make the behavior more dynamic based >>> on the system, but realistically, there are close to zero remaining >>> users on any ARM11MPCore anyway, and nobody seems too interested in it, >>> compared to the more popular ARM1176 used in BMC2835 and AST2500. >>> >>> The Oxnas platform has some minimal support in OpenWRT, but most of the >>> drivers and dts files never made it into the mainline kernel, while the >>> Arm Versatile/Realview platform mainly serves as a reference system but >>> is not necessary to be kept working once all other ARM11MPCore are gone. >> >> Acked-by: Neil Armstrong >> >> It's sad but it's the reality, there's no chance full OXNAS support will >> ever come upstream and no real work has been done for years. >> >> I think OXNAS support can be programmed for removal for next release, >> it would need significant work to rework current support to make it acceptable >> before trying to upstream missing bits anyway. > > Ok, thanks for your reply! > > To clarify, do you think we should plan for removal after the next > stable release (6.3, removed in 6.4), or after the next LTS > release (probably 6.6, removed in 6.7)? As far as I understand, > the next OpenWRT release (23.x) will be based on linux-5.15, > and the one after that (24.x) would likely still use 6.1, unless > they skip an LTS kernel. I think it's ok to remove it ASAP, or at least before the next LTS, not having SMP makes the platform barely usable so the earliest is the best. Neil > > Arnd