From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f173.google.com (mail-pl1-f173.google.com [209.85.214.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 84C0B2FB6 for ; Wed, 19 May 2021 06:54:34 +0000 (UTC) Received: by mail-pl1-f173.google.com with SMTP id v13so6459912ple.9 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=IC4Sf2rYITMoW/aJ4Yhvu8gjSfW9kJC7MJBG7rrBcbRGEdP7du9oAus+EfcRbc3pLz 7HeBfI1IcIons6/wAeIHKXzbhiHQke8dZiEmy497BYKdWEVhes9OPNQVgf0Vgy+hO41y lFM4lulaRBnB95vH1YvmL6dA5rI7+cmLnvQW95HqD4xJ8O7QNo9ufUXGyBEfx9vfKxhn XsDaw0Ww2JMXSE+vtWvz/VA07Ud/AKQG9NRvTvFZhfcTtqX9to3gJPueBEOEXvKgQVgQ Au0LgaTxhsEEAKSqyPc9tC67mEDCFsfxGQ7I556D4B0C5mybjZMQBRxtwBVDou91altz D/mg== X-Gm-Message-State: AOAM531LGwShLlUYQI4Oby9bO0SZj9SZCnG+Y/MugSWOxnlPQqvuHD3C cW1C/5eFYkBAm90GifIV3JSbsA== 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> X-Mailing-List: linux-sunxi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210519060617.GA28397@lst.de> 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