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 CA207C636D7 for ; Wed, 1 Feb 2023 06:31:53 +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:MIME-Version:References: Message-ID: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=6eX/A7pIlZv1QrKvDBr7QaXABeJIxB3H39TuobbywNQ=; b=UXX3NNzPPRJia0 x8ZdZcIfUJ5C+tmo4CbvyPinh+eVqyrc5q6PMo4a7OWIQVUxsMAUljcgY5fKsNqJhLOgJ5kDTZHcX 9sBdv86FCOGB4sI9s8vvOGL6tJU9EhZ8zubQw2rypn9vWz/AvldHjGw2yW2O36B0aZdYu0HCqsad1 yxXkWFPWAS4IEGvoj2DX+3JdK5tduAmE3tR5qx20BHoMgq9oEA9OJ9pyW1s0F7NBC1eEtAnZ0vURl 9B0m+r4OA9gWMVYnUuWRA92pJUS4vPaqVxdDzLaaHs6XIiqudHc4GNaqNrmzPL+jjNPNs8TYBZkfk 5ssUPLTk7JC0SSy0TfcA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pN6eo-00ATMQ-TW; Wed, 01 Feb 2023 06:31:46 +0000 Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pN6el-00ATMB-Va; Wed, 01 Feb 2023 06:31:43 +0000 Date: Tue, 31 Jan 2023 22:31:43 -0800 From: Christoph Hellwig To: Matthew Wilcox Cc: "Lad, Prabhakar" , Linux-MM , linux-riscv , Linux-Renesas , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Palmer Dabbelt , Arnd Bergmann , Rob Herring , Krzysztof Kozlowski , Jessica Clarke , Geert Uytterhoeven , Fabrizio Castro , Biju Das , Chris Paterson Subject: Re: [QUERY]: Block region to mmap Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-BeenThere: linux-riscv@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-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Mon, Jan 30, 2023 at 03:24:40PM +0000, Matthew Wilcox wrote: > > Basically we are making use of the memory protection unit (MPU) so > > that only M-mode is allowed to access this region and S/U modes are > > blocked. > > This sounds like RISC-V terminology. I have no idea what M, S or U > modes are (Supervisor and User, I'd guess for the last two?) Yes, M = Machine, S = Supervisor, and U = User. M omde is the absolutele worst idea of RISC-V and basically a mix of microcode and super-SMM mode. > Before we go too deeply into it, how much would it cost to buy all of > these parts and feed them into a shredder? I'm not entirely joking; > if it's less than the software engineering time it'd take to develop > and support this feature, we should do it. The above suggests this is in no way an actual hardware problem, but the stupid decision is done in the M-Mode firmware. I think it is very reasonable to simply not support the devices in Linux until the firmware is fixed. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv