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 5B282C433EF for ; Tue, 12 Jul 2022 20:45:43 +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:MIME-Version:References:Message-ID: In-Reply-To:Subject:cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=/7TJw3fuBRq+ZTO1ThVKDUNZJYcv5xad20RRsbUTCBA=; b=3YKYCsRz5oAvTR luuNIXtFyksDHJWnCiqrC9Jgv9UgoxDXyGGPjB6lB9sARKhu+ChlSQkIpnloewb0BH3S+bOcbrjQ/ W4WOItdiRep7oPb1d34KjZQN60g3ndZef856ZLFJjtftiH39ZOG1mos+ObCJT6VCoJOTIAmPe5jvl roHNp6wTvn7UqEDigL/Xq8VhQZWBavBzre6dLROOGWCqe07OPv0Pl4VqtqlWs1M9U+SDbJXvXYqPo vr3RGZcfPbst3LW6+Rd8wmDtUzlZONPJNFfcA8dkhiT3D9GCHNjzxjWc9pHOTyB0G/VUC1a9YA4Kh nKaXAssvqiFHsKS9pcOw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oBMkN-00Efh3-Sh; Tue, 12 Jul 2022 20:44:44 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oBMkJ-00Effv-R8 for linux-arm-kernel@lists.infradead.org; Tue, 12 Jul 2022 20:44:41 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B051161A6D; Tue, 12 Jul 2022 20:44:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D42DBC3411E; Tue, 12 Jul 2022 20:44:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657658678; bh=1IsnqnbTMB+Y3xwhSMiGqcgC2tO2w7hArZeQvTTCvtc=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=gV+C8g8kjTKdiItadcHpywtFUmGPvmeoBsyjllauaZTBOmzPmnK3UVOk1qjLjJ8Go TQ06xGqh3CY7wmX9n6uRR3aioDUzq31vz3Pr24XvxAX8R/R1QoE+O/jN4tJ1TeS9Rk M6Aaz5azTU9WHGcEFENiDH+N8GvYjjuYIVrsO+Po2S1fA51pF/YHns6s6Gb4GjTq1b LMz+flEOstQJNjTRfqsHgFCWt0ExAuQix7jdF91VGxl0N6K+uXWsZ0j9MSppr+WiuX +xYKKAMeD+PSGYvm9eGSsZgJZo4V6vtPtmc3oLW9MTEuAzV3rqrLDc64Zad7sq7VsC bERR/KFLr+AuQ== Date: Tue, 12 Jul 2022 13:44:26 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@ubuntu-linux-20-04-desktop To: Arnd Bergmann cc: Vladimir Murzin , Linux ARM , Ayan Kumar Halder , Stefano Stabellini Subject: Re: [RFC PATCH 0/3] ARM: Support Cortex-R platform(s) In-Reply-To: Message-ID: References: <20220630083641.21835-1-vladimir.murzin@arm.com> User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220712_134439_977171_A4F1C7AF X-CRM114-Status: GOOD ( 33.36 ) 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 Tue, 12 Jul 2022, Arnd Bergmann wrote: > On Tue, Jul 12, 2022 at 10:33 AM Vladimir Murzin > wrote: > > On 6/30/22 09:36, 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 > > > > > > [1] https://developer.arm.com/downloads/-/download-fpga-images > > > > Anything I can do to make progress with the series or it falls under > > "we do not care" category? > > I think at this point it's an actively bad idea to merge support for Cortex-R. > > I don't think anyone else cares, but if you can find other people that want > this to get merged (and know what they are talking about), you can > overrule me on this. > > The existing MPS2 support is important because it gives developers > an easy way to test Cortex-M based NOMMU code, and we still have > users on STM32 at least. I do expect the STM32 MCU user base to > further shrink, to the point where nobody is updating their kernels any > more and we want to remove not just STM32 but all other Cortex-M > platforms. All others are already further down the road of decline and > MPS2 is not useful by itself. > > Merging MPS3/Cortex-R52 now feels like a step in the wrong > direction, if that leads to a future situation where we remove > Cortex-M but keep Cortex-R support around. I think this series is really cool if nothing else as a demo, so please make it available somewhere on kernel.org or github with some docs on how to use it because I am certain someone is going to try it and show it as a PoC (R52s are still going to be around for a long time). Your efforts are not going to go to waste :-) On upstreamability: if the issue was just lack of reviews I can find time to step in and review the patches. But if the general idea is that we don't want to keep the code upstream in Linux then I am happy to go with Arnd's recommendation not to merge. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel