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Date:   Wed, 19 May 2021 08:56:58 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Drew Fustini <drew@beagleboard.org>
Cc:     Christoph Hellwig <hch@lst.de>, Guo Ren <guoren@kernel.org>,
        Anup Patel <anup.patel@wdc.com>,
        Palmer Dabbelt <palmerdabbelt@google.com>, wefu@redhat.com,
        lazyparser@gmail.com,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        linux-sunxi@lists.linux.dev, Guo Ren <guoren@linux.alibaba.com>,
        paul.walmsley@sifive.com
Subject: Re: [PATCH RFC 0/3] riscv: Add DMA_COHERENT support
Message-ID: <20210519065658.GB31590@lst.de>
References: <1621400656-25678-1-git-send-email-guoren@kernel.org> <20210519052048.GA24853@lst.de> <CAJF2gTR5838=Uwc5P6Xs=G7vk80k0yqWcSsNe0OFcwc9sDBBHg@mail.gmail.com> <20210519060617.GA28397@lst.de> <20210519065431.GB3076809@x1>
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On Tue, May 18, 2021 at 11:54:31PM -0700, Drew Fustini wrote:
> 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.

Then the vendors need to push harder.  This problem has been known
for years but ignored by the vendors.