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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 ACB83C433EF for ; Thu, 30 Jun 2022 21:18:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:Subject:Message-ID:Date:From: In-Reply-To:References:MIME-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ZPuaIM4gARYTZsw5RVSIdS9MACM+BpnZjwcH07Tnmlk=; b=XIV9VTvWarP5lT OcPruR4ryoo2K4LHsj628ejwn7578yNVPvxXxTWzanVC6Kaa6RnA++44LpQ8QawZIQ8ng8DzEUiF0 v9CBdbJfcG20/rcrVfOmHlGaiKOhFDmq0FNDXWhfk/JRsVJS4C9YIhbfCpULN9MkVHZQlWEfYvUpP ojCsY0uIDqGSTgrM89b6mFV3WEG4rYcJDpxolNif7jzAsX9nIZAB6A2oZoav+0Jg2eaEtejAlNUF7 9VMxAFw48RPp7Xv/fpGryFUXOLN58Qz4A/4NRbJ8WJnBttPxLM/b43Elp7KiSWFMr2Xi5TUU4L+LA ktTdN0WVlkqinl7U5uLA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o71Xk-001bpk-On; Thu, 30 Jun 2022 21:17:45 +0000 Received: from mout.kundenserver.de ([212.227.126.135]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o71Xg-001bo3-Te for linux-arm-kernel@lists.infradead.org; Thu, 30 Jun 2022 21:17:42 +0000 Received: from mail-yw1-f176.google.com ([209.85.128.176]) by mrelayeu.kundenserver.de (mreue010 [213.165.67.97]) with ESMTPSA (Nemesis) id 1Mt7Pt-1nniPL1L21-00tV62 for ; Thu, 30 Jun 2022 23:17:38 +0200 Received: by mail-yw1-f176.google.com with SMTP id 00721157ae682-31bf3656517so5498607b3.12 for ; Thu, 30 Jun 2022 14:17:38 -0700 (PDT) X-Gm-Message-State: AJIora97NJMtBsXF4o/ukqg6O7LubX5m1NWZ/y2JrD0v7ubrZBNS52z3 Y0DFB23Vtr2QlbiaiothfrAidShtKSRDAhMvGTs= X-Google-Smtp-Source: AGRyM1tfr9aaXmUZV+8r39EvJXcvJGK7toankdYy/SxPxxyY66/l5DNRHbwjm7w73KavO5ITmNtSgaOPqOSGGR4BJZE= X-Received: by 2002:a81:7742:0:b0:318:35e9:728b with SMTP id s63-20020a817742000000b0031835e9728bmr12900164ywc.209.1656623857117; Thu, 30 Jun 2022 14:17:37 -0700 (PDT) MIME-Version: 1.0 References: <20220630083641.21835-1-vladimir.murzin@arm.com> In-Reply-To: <20220630083641.21835-1-vladimir.murzin@arm.com> From: Arnd Bergmann Date: Thu, 30 Jun 2022 23:17:20 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC PATCH 0/3] ARM: Support Cortex-R platform(s) To: Vladimir Murzin Cc: Linux ARM , Arnd Bergmann , Ayan Kumar Halder , Stefano Stabellini X-Provags-ID: V03:K1:JeRlkY13gBfoS1hrIJjoPZIVRKug3zOf/Arw1P9wBzoNsLi3QdN AbWaKN9T2ghKZQtenFQWpmmW6aCQ2plq0hx60Ih4Y6K1yVRQFFAiQSRjAyQuQ8m6ctqjPf0 l2TKWUHQgJC1oapsuBqhUx5exu4tz3TPQ64DlCO9Qdl42XflTLmwBNU5Qc5BMAFHwWMSgEs oCwkE3VNGPuMuRHJ6F6WA== X-UI-Out-Filterresults: notjunk:1;V03:K0:1/rgki8Y6SQ=:eWtEZOxE1+nEqUtUL0cdhL xrjUlh0u0HEvrUf/70k+75pRRg1SM0tG/7qcMT9n/yCOy9V8M2IPTHGlpKDbDuWoL3xIzzVTR H/jmz7YL/XISCOxvSlwkOkCx3EsJp/F4L+TlHjnw8/E8Kq8Izwz9tt0dOWuCPO1mnf0wJqw/l ctsKfq9erj0XBroJYRM5Tv/xRtkrsY6cJRa6HxwG9utZHiCeGsfh0gpfd/Gbu1F8C8AUI15xj tsDM//Hf880mcGU5oxhiklwsnF1Dx46A7LQv32VrDHkillzjEPQabqYTAlZRXBginLXE/Nmz0 PZ/AXiIr/Sf/HLRZQ52Y/jlNrV5bjrgKcym5NwkB2UH6wju8d9wjs3n8uYzp2HK3A0lvC5UP2 dFPWvOeTzStvs7zk6t2vodla5oMvATL6KALxX9GMT8RB+4X7yaQp919Jss76AvrBYMNnhUuxF LJhYOBpEa6cWeazSuZR1RtNOfvCqbDjWR05K7d71gsYIU6aEX+bBhpWLs14LZz2t7MOX0lsXv ZXVdapWBphb8+oEELk+rLwYpjA7Ctx6m+/3vEFxgHThIeWbZE6sB6ZMJ1HvL4N2Nr36cNukOF a+CcVKPDi82HZHJGD8oCoj+HvDsdhMDO7gVSaALVzsz5Q2SLqLUDGuyJgF84r7ynoobBYnMRW 6KE02+d43K/tzv4DuAxMBcXwG9ME1eoxufZ+xkP4X7lRCozfvZgdgidlVbfToSclX/6pr+Naw r9qqml+/ubDCw76AU0jlgnMyk4sfytG+7js6Cw== X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220630_141741_288483_243D507E X-CRM114-Status: GOOD ( 18.69 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jun 30, 2022 at 10:36 AM Vladimir Murzin wrote: > > I've been running Linux on Cortex-R cores with downstream patches for > several years already. There are few reasons why we have not got any > real platform supporting Cortex-R cores so far: > 1) lack of interest > 2) lack of easily available platforms > 3) missing Kconfig bits > > During these years I've been receiving questions (mostly in private) > about running Linux with Cortex-R cores. Use cases vary, but mostly > fall under "we know Linux and do not want yet another RTOS", also > people not always care about real-time features of R-class cores and > see it as an upgrade from M-class cores. > > Sometime ago MPS3 platform got support for FPGA image [1] with > Cortex-R52 cores where Linux can live comfortably. > > This patchset addresses #3 and brings support for MPS3 platform > featuring Cortex-R52 The patches look ok to me, if we want to support Cortex-R, this is clearly how it should be done. My main concern is the same as the one we discussed before: are there actually use cases for which running Linux con Cortex-R is the right thing to do? While it's clearly an awesome hack that this actually works, I don't really want to encourage developers to ship products with Linux on Cortex-R unless there is at least one sensible use case for it. The Cortex-M support is still holding up for the moment, but I don't think there have been any new deployments in years (there are a few new hobbyist projects like the imxrt and the stm32 art pi), and I expect that we will want to completely remove nommu support at some point. Arnd _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel