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Fri, 09 Nov 2018 21:12:51 -0800 (PST) MIME-Version: 1.0 References: <4aef7216-726c-f565-5c0f-cebd2aefb46d@wdc.com> In-Reply-To: <4aef7216-726c-f565-5c0f-cebd2aefb46d@wdc.com> From: Luke Kenneth Casson Leighton Date: Sat, 10 Nov 2018 05:12:39 +0000 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [sw-dev] SBI extension proposal v2 To: atish.patra@wdc.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181110_053135_284721_A94875A8 X-CRM114-Status: GOOD ( 12.70 ) 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@gmail.com, alankao@andestech.com, abner.chang@hpe.com, Anup Patel , Palmer Dabbelt , agraf@suse.de, zong@andestech.com, Alistair.Francis@wdc.com, paul.walmsley@sifive.com, mick@ics.forth.gr, sw-dev@groups.riscv.org, 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 Message-ID: <20181110051239.d0OP7FmBi8IHDYa5zKSW-96ChCuoLVR7jdityDugebo@z> On Sat, Nov 10, 2018 at 2:42 AM Atish Patra wrote: > ## Conclusion > This proposal is far from perfect and absolutely any suggestion is > welcome. Obviously, there are many other functionalities that can be > added to this proposal. However, I just wanted to start with something > that is an incremental change at best to kick off the discussion. The > aim here is to initiate a discussion that can lead to a robust SBI > specification. very cool, atish. i would very much like to see the optional addition of multiple serial lines, by adding a getchar and putchar function that takes just one extra argument: the serial line index. there are a lot of different uses to which mult-serial lines may be put: * boot message separation from console login * boot management separation from other purposes (u-boot/coreboot) * virtual /dev/ttyS0-3 * clean UPS reporting and management * remote virtual machine power management (power-on / off) * simple bog-standard multiple virtual login consoles * separation of debug messages (stdout/stderr) to ease debugging and development * remote and virtual OpenOCD and kernel debugging without disrupting the main serial console * PPP serial links. this latter is one that i am particularly interested in, as i would like to be able to boot a full GNU/Linux OS on spike, given the lower barrier to entry in making modifications and experimenting with spike than it is with qemu. if spike were able, through a multi-serial SBI interface, to have a PPP serial line, it would be possible to run a root NFS (or other network block device) without having to sacrifice console access. it would be possible to create an initramfs from a lower-capability system like buildroot, containing PPP, enable it, and pivot-root out to a full stock GNU/Linux OS such as debian or fedora. so there are huge benefits, reducing the development barrier to entry into RISC-V experimentation and debugging, and opening up a much wider range of capabilities and possibilities for machine and virtual system management. l. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv