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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0618BC433B4 for ; Wed, 19 May 2021 05:20:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D9B5C61355 for ; Wed, 19 May 2021 05:20:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237169AbhESFWM (ORCPT ); Wed, 19 May 2021 01:22:12 -0400 Received: from verein.lst.de ([213.95.11.211]:36587 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229598AbhESFWL (ORCPT ); Wed, 19 May 2021 01:22:11 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 2DEDA67373; Wed, 19 May 2021 07:20:49 +0200 (CEST) Date: Wed, 19 May 2021 07:20:49 +0200 From: Christoph Hellwig To: guoren@kernel.org Cc: anup.patel@wdc.com, palmerdabbelt@google.com, drew@beagleboard.org, hch@lst.de, wefu@redhat.com, lazyparser@gmail.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-sunxi@lists.linux.dev, Guo Ren Subject: Re: [PATCH RFC 0/3] riscv: Add DMA_COHERENT support Message-ID: <20210519052048.GA24853@lst.de> References: <1621400656-25678-1-git-send-email-guoren@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1621400656-25678-1-git-send-email-guoren@kernel.org> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 19, 2021 at 05:04:13AM +0000, guoren@kernel.org wrote: > From: Guo Ren > > The RISC-V ISA doesn't yet specify how to query or modify PMAs, so let > vendors define the custom properties of memory regions in PTE. Err, hell no. The ISA needs to gets this fixed first. Then we can talk about alternatives patching things in or trapping in the SBI. But if the RISC-V ISA can't get these basic done after years we can't support it in Linux at all. 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 X-Spam-Level: X-Spam-Status: No, score=-5.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8EBD3C433ED for ; Wed, 19 May 2021 05:21:15 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 45D20610CC for ; Wed, 19 May 2021 05:21:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 45D20610CC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; 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=WqKkM2A+018iJkR9paZDe8+oV7qgKpnQ35D4sSYG0i4=; b=HSJcnxe3PhA/iNRez8Y6FMMX6 v2LRzNmtPqLoCFOxU8jLkQ60oADiSynpxbCCIOruvdeRH45hzkKnvt0tj+pCJ23q2XoV6EWbI4a25 xLtr55i+0drqt0DVSEv7SuZDQEO31alPzIJ9epUzrlLXqhtduAG63WdHsBBDhAac+T2GF8gPpZteA j08nKjw2KruImROeOqCRwBBFcVdb4izEV/jcWPnYC0UtRQDKEA0E91DuWtMKx7+EwTQL1BmTwpwWM oax5s/LOxElH3wBGhG8TeXz2IpY/R7zEJ4qxsxD+P1FNSXpOKVNi+Jb1ulktO6opWOFF2EOFLiHB8 vJJmYZAwQ==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1ljEdg-002qMi-9k; Wed, 19 May 2021 05:21:00 +0000 Received: from bombadil.infradead.org ([2607:7c80:54:e::133]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1ljEdc-002qMU-GW for linux-riscv@desiato.infradead.org; Wed, 19 May 2021 05:20:58 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=wWRRLV9lR6OczLC+O9YUr3mFCqNUEgiS2MD5Uq0NFFc=; b=IBm4YBUgektpc2qIBoeTeyTGnD cAhslFnh7SDLXOFuHFXI9ULZoiCpdkdZ/UkkMkh/gd6njcRFJtBSlgsgpNH5jKAQRrAwhaGdGN1Cz H4827o1erHPVRx8rABhNCSVz4GGSqOucV7t7wMMO+wAZu1o++ioaschjjQnyRfH740YNuUbO1r7h5 N3+ken8T/hJvrGYT3pqM9MCgU0aXlFXfeOLUUeK69SXmwD2QiL6HsooOp13NkIk0JN9gh2OJkbmBx 3Cf9VGsEykALyhE0WJffesX1jZVAaRnZrayWHVgLL+jL37qyJWq8xUe8L87e/7EHEoEB8KvfmdMvD kNQhyAAw==; Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1ljEdZ-00F8uW-N8 for linux-riscv@lists.infradead.org; Wed, 19 May 2021 05:20:55 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 2DEDA67373; Wed, 19 May 2021 07:20:49 +0200 (CEST) Date: Wed, 19 May 2021 07:20:49 +0200 From: Christoph Hellwig To: guoren@kernel.org Cc: anup.patel@wdc.com, palmerdabbelt@google.com, drew@beagleboard.org, hch@lst.de, wefu@redhat.com, lazyparser@gmail.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-sunxi@lists.linux.dev, Guo Ren Subject: Re: [PATCH RFC 0/3] riscv: Add DMA_COHERENT support Message-ID: <20210519052048.GA24853@lst.de> References: <1621400656-25678-1-git-send-email-guoren@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1621400656-25678-1-git-send-email-guoren@kernel.org> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210518_222053_925997_C0B75943 X-CRM114-Status: GOOD ( 10.57 ) 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 Wed, May 19, 2021 at 05:04:13AM +0000, guoren@kernel.org wrote: > From: Guo Ren > > The RISC-V ISA doesn't yet specify how to query or modify PMAs, so let > vendors define the custom properties of memory regions in PTE. Err, hell no. The ISA needs to gets this fixed first. Then we can talk about alternatives patching things in or trapping in the SBI. But if the RISC-V ISA can't get these basic done after years we can't support it in Linux at all. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv