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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 24451C433ED for ; Wed, 19 May 2021 06:54:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 078E661364 for ; Wed, 19 May 2021 06:54:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231760AbhESG4G (ORCPT ); Wed, 19 May 2021 02:56:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50370 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230003AbhESG4G (ORCPT ); Wed, 19 May 2021 02:56:06 -0400 Received: from mail-pl1-x630.google.com (mail-pl1-x630.google.com [IPv6:2607:f8b0:4864:20::630]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86D1CC061760 for ; Tue, 18 May 2021 23:54:34 -0700 (PDT) Received: by mail-pl1-x630.google.com with SMTP id t21so6480918plo.2 for ; Tue, 18 May 2021 23:54:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=beagleboard-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=2ScD741o+QURZZPw733RWWmwYXPFhfmlwQ+Cj/Nypb0=; b=cX7NlRVxOwOKhhSA4/69Ayqnip1ZqdQVgVcbl0bX/edQVkh3QLIKaii0yMSLrECxj+ Dbvotak+LCZxfuQOc3f08xucZP8jQokPJjyMHYeBXHENqK/U3qXyjtgWmJHXc7f91PK6 KTMoO0H4H0HWHbBk/0OR2tXgoAB93ZoPznOd/ACvhTFzSUwvaWppBpmZVbDyVNhneDmk KZVYGuEQOSKMWnh0kaRc34BqlJZoGw4bfVbgsHdbSK1UviGHP3zRK1BgqUC1A9dVSviH /KOgvBznGPu7GY8wGtR9tBiTF2fmLca+yccav0EOn60Oy/SUssiHLMUDAiJ4PBEenpbV 4lXg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=2ScD741o+QURZZPw733RWWmwYXPFhfmlwQ+Cj/Nypb0=; b=Ba5jtW0bkrh/1VyYOrg4H9kCv12Yn0Bv7vFopbq2U47TVLGHHTNBbcls8QJa2A+hpU 4ISKG6q4OIZXvDxAt5heKA7rNsNhQNavqQuQo0p+0FHR1uFOsY4hrWOJP817IbMv1RCq Da3FF4wu8BYBk3iagkA/60uLEkSDwcGJuRE6arPnJZYOVo1A5bgWL4kOxMOtclrokTyr pLXuOEMgkqf90jnQ6mbsqAj/Zpp7rkJxHBbmGGLKZEd8GHEaVzyp8PW08EQDpbR3Vq90 3VlNZQcK5JcP2dk205XVmKK/6RTh0cy2aMl683JIq/wBb9thr7OC2uC4X5sIn0WCGgZF DlZw== X-Gm-Message-State: AOAM5319cX9kMDBFumnqQgeZ+0qBF9YTAP2q1sjIDfJaxQcVIHjIodk7 Kp2uZD++M1D33W5oPcDsYOrWMw== X-Google-Smtp-Source: ABdhPJx+meH2AZClfHyVtpeacNdTvFk5+2vdyzAovgo9a7hj5AkNu+XhOzxniHuRliV60D2l7mpiQA== X-Received: by 2002:a17:90a:560b:: with SMTP id r11mr10039603pjf.224.1621407273992; Tue, 18 May 2021 23:54:33 -0700 (PDT) Received: from x1 ([2601:1c0:4701:ae70:9384:8c4b:dc2b:c4d0]) by smtp.gmail.com with ESMTPSA id k14sm5063003pfu.80.2021.05.18.23.54.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 May 2021 23:54:33 -0700 (PDT) Date: Tue, 18 May 2021 23:54:31 -0700 From: Drew Fustini To: Christoph Hellwig Cc: Guo Ren , Anup Patel , Palmer Dabbelt , wefu@redhat.com, lazyparser@gmail.com, linux-riscv , Linux Kernel Mailing List , linux-arch , linux-sunxi@lists.linux.dev, Guo Ren , paul.walmsley@sifive.com Subject: Re: [PATCH RFC 0/3] riscv: Add DMA_COHERENT support Message-ID: <20210519065431.GB3076809@x1> References: <1621400656-25678-1-git-send-email-guoren@kernel.org> <20210519052048.GA24853@lst.de> <20210519060617.GA28397@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210519060617.GA28397@lst.de> Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Wed, May 19, 2021 at 08:06:17AM +0200, Christoph Hellwig wrote: > On Wed, May 19, 2021 at 02:05:00PM +0800, Guo Ren wrote: > > Since the existing RISC-V ISA cannot solve this problem, it is better > > to provide some configuration for the SOC vendor to customize. > > We've been talking about this problem for close to five years. So no, > if you don't manage to get the feature into the ISA it can't be > supported. Isn't it a good goal for Linux to support the capabilities present in the SoC that a currently being fab'd? I believe the CMO group only started last year [1] so the RV64GC SoCs that are going into mass production this year would not have had the opporuntiy of utilizing any RISC-V ISA extension for handling cache management. Thanks, Drew [1] https://github.com/riscv/riscv-CMOs