Re: [sw-dev] SBI extension proposal v2

From: Damien Le Moal <Damien.LeMoal@wdc.com>
To: "ron minnich" <rminnich@gmail.com>,
	"Luís Marques" <luismarques@lowrisc.org>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>,
	Christoph Hellwig <hch@infradead.org>,
	Olof Johansson <olof.johansson@gmail.com>,
	"alankao@andestech.com" <alankao@andestech.com>,
	"abner.chang@hpe.com" <abner.chang@hpe.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Palmer Dabbelt <palmer@sifive.com>,
	Alexander Graf <agraf@suse.de>,
	"zong@andestech.com" <zong@andestech.com>,
	Atish Patra <Atish.Patra@wdc.com>,
	"sw-dev@groups.riscv.org" <sw-dev@groups.riscv.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Anup Patel <anup@brainfault.org>,
	"mick@ics.forth.gr" <mick@ics.forth.gr>,
	Alistair Francis <Alistair.Francis@wdc.com>,
	Luke Kenneth Casson Leighton <lkcl@lkcl.net>,
	"linux-riscv@lists.infradead.org"
	<linux-riscv@lists.infradead.org>,
	Andrew Waterman <andrew@sifive.com>
Subject: Re: [sw-dev] SBI extension proposal v2
Date: Wed, 6 Feb 2019 07:54:26 +0000	[thread overview]
Message-ID: <BYAPR04MB581629EFFF1EAE6CE1A6A4F9E76F0@BYAPR04MB5816.namprd04.prod.outlook.com> (raw)
In-Reply-To: CAP6exYJNWRuW6P3BXu6XfcZOKiCECjsv3SJQ14uMxQY0Ypg1pQ@mail.gmail.com

On 2019/02/06 16:03, ron minnich wrote:
> While I respect the tremendous amount of work the OpenSBI authors have
> done, I agree with Benjamin and Luis.
> 
> There is a further issue that occurred to me doing their excellent
> FOSDEM talk, which is that nowhere in this has any kind of verified
> boot scenario been discussed, and if you don't get that thinking in
> from the start it is very hard to wedge it in later.
> 
> I think we should consider the OpenSBI in its current state a starting
> point for figuring out what we need to do.
> 

And this is exactly why we wanted OpenSBI released as soon as possible, before
even going further with cleaner specification documents for standardizing new
SBI calls beyond the currently defined legacy calls.

OpenSBI as it is now is indeed a starting point, a base we can use to explore
different design directions and implementations of RISC-V SBI interface, or its
lack for direct M-mode boot cases for application software (OSes) with full
support of a known platform.

Going forward, PMP and other security related features will need to be
considered and addressed and we hope that OpenSBI can also be used as a
reference implementation for any such early setup that the platform or OS may need.

There is still much to discuss, prototype and decide. OpenSBI will help in this
process providing an open reference implementation for all to see.

-- 
Damien Le Moal
Western Digital Research

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