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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Rv6C7HmIpYA4RmtRzHWQ7pu2tyJRoMnmtPJgJ/hjc94=; b=Knf+nvEfp+ZQEql2RHyqAqFLwinoEVXXuCT+SeorNb5kBdwKQpzjgb8eVpJvybww63 8ltwf0n7HHf8AryI/rqItc+62PvlwxYrfiP4Ofbs/7VXIDEEqLY/FKmX8VWi2n3CwxP3 iesFVQ2CTeq9eWgERqK5TPijWtSUoKHFVgwQ54b9vWosQMF8JJZJSQiAbYmq/ApcGYoz DGtu3uV/hwhYLPYVivH7K9khjmlmVuDPB9gEUjO8+99TUIpDqy+qR9tgQ5JGzgzhU/YR JfYy5vevhAISt4HjEKTp3Gl6iQAJo0Z4rKFSm8advx7ulcy3L1HeTwycof2lM4bAxTet jJgA== X-Gm-Message-State: AJcUukd+2sBxSO04F4nCCVVdsuXg42HbABAHOqnlPYh/6oTmcugtL9tc 65VHpN62NSShjGxE19MfJg5IoB8MbzG4NdDt3pw= X-Google-Smtp-Source: ALg8bN6bB7SBAmuyzsUzwKIrimbOJimpmpV/s21Hd/pDdcMk0jSHmBQhyDXHLYkhZfhRIqWais7c7f9L6QFE8aeyu9E= X-Received: by 2002:a67:efd1:: with SMTP id s17mr10571575vsp.119.1548733995407; Mon, 28 Jan 2019 19:53:15 -0800 (PST) MIME-Version: 1.0 References: <4aef7216-726c-f565-5c0f-cebd2aefb46d@wdc.com> <2e5329eff04e2b0bc2433b5d974bf10f@mailhost.ics.forth.gr> <7efecac7-17bd-5fc1-d0de-9fd498db4751@wdc.com> <452be0d3-da8e-643e-9f91-c38f0af36ffd@suse.de> <033872b8-49d5-2731-118f-967488f4763f@suse.de> <09bede45-6ecf-4ded-8615-0be38aac33fc@groups.riscv.org> In-Reply-To: <09bede45-6ecf-4ded-8615-0be38aac33fc@groups.riscv.org> From: Samuel Falvo II Date: Mon, 28 Jan 2019 19:58:00 -0800 Message-ID: Subject: Re: [sw-dev] SBI extension proposal v2 To: Paul Miranda X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190128_195319_046609_72A248D3 X-CRM114-Status: UNSURE ( 7.57 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, hch@infradead.org, Damien.LeMoal@wdc.com, Olof Johansson , alankao@andestech.com, "Chang, Abner" , Benjamin Herrenschmidt , Palmer Dabbelt , Alexander Graf , zong@andestech.com, atish.patra@wdc.com, RISC-V SW Dev , paul.walmsley@sifive.com, Anup Patel , mick@ics.forth.gr, Alistair.Francis@wdc.com, Luke Kenneth Casson Leighton , linux-riscv@lists.infradead.org, Andrew Waterman Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org On Mon, Jan 28, 2019 at 7:48 PM Paul Miranda wrote: > I don't know enough about the rest of this thread to comment intelligently, but I'm curious what you advocate with respect to PMP? > I believe it has usefulness in allowing M mode code to protect it from itself. Is your only concern that it may be used by ROM code that is not replaceable? > It's definitely not the first protection scheme I've seen that uses lock bits. If I understand Ron's emails correctly, he already indicated his experience with such systems, and is basing his dislike of PMP expressly on that experience. It seems history records this feature being abused rather profusely. -- Samuel A. Falvo II _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv