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 3A37CC433EF for ; Fri, 1 Jul 2022 09:40:30 +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:In-Reply-To:From:References:Cc:To: Subject:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=N5yck+ndnkLGUOcRGKKnCVIhH8TTLC7y5jFBJkGw9/4=; b=SawHjDxCgcSsuK WYlKPYs5JEq5BG7uxF/2hu+iRyxrZSNkKYQxIiWsO/+HBe9qKx07CARyWf7gUDPDxbdtl2w8+WUGR aozpMcYa6EnYh3oRveC6QgOaGxdAwIqd1AI6b2nrtIeLVa136x6R540Br0Q2mHx0lUeTxvB7D9NXo o17FqJh08nrUY+V4HLFJa7lpQl6CnhH3He1epozGM+/svuZRqqZzIOuWWn6QLQrOXq9dnWBstM0bc bXOJRZf6BJJuQ3KVTtG5EOMD6UTkYdhndlcZLgN2dX29MEqszElk6SBXurdeadOq2XJtD4EZiOV8W iylEAikNCA3nvNAmvThA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o7D7e-003u5F-Bu; Fri, 01 Jul 2022 09:39:34 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o7D7a-003u46-Iq for linux-arm-kernel@lists.infradead.org; Fri, 01 Jul 2022 09:39:32 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 205AF106F; Fri, 1 Jul 2022 02:39:28 -0700 (PDT) Received: from [10.57.10.28] (unknown [10.57.10.28]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CA6043F66F; Fri, 1 Jul 2022 02:39:26 -0700 (PDT) Message-ID: <704f0210-59c5-2313-f41d-93d7a6e80b0f@arm.com> Date: Fri, 1 Jul 2022 10:39:26 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [RFC PATCH 0/3] ARM: Support Cortex-R platform(s) Content-Language: en-US To: Arnd Bergmann Cc: Linux ARM , Ayan Kumar Halder , Stefano Stabellini References: <20220630083641.21835-1-vladimir.murzin@arm.com> From: Vladimir Murzin In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220701_023930_723367_2427F95A X-CRM114-Status: GOOD ( 21.48 ) 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 6/30/22 22:17, Arnd Bergmann wrote: > 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. Thanks! > > 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? Unfortunately, people who have been wondering how to run Linux on Cortex-R are not keen to uncover their use cases it details. Maybe that for quick prototyping or just curiosity... > > 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. It could be that already happening and we are not aware because area of application might not be visible or broad. > > 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. At least for M-class I was told about commercial application (yet in low volume) - the reason why Linux was exactly "we know Linux and do not want yet another RTOS" Cheers Vladimir > > Arnd _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel