Re: [sw-dev] SBI extension proposal v2

From: ron minnich <rminnich@gmail.com>
To: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>,
	Bruce Hoult <brucehoult@sifive.com>,
	Damien Le Moal <Damien.LeMoal@wdc.com>,
	Olof Johansson <olof.johansson@gmail.com>,
	"alankao@andestech.com" <alankao@andestech.com>,
	"abner.chang@hpe.com" <abner.chang@hpe.com>,
	Christoph Hellwig <hch@infradead.org>,
	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>,
	"linux-riscv@lists.infradead.org"
	<linux-riscv@lists.infradead.org>,
	Andrew Waterman <andrew@sifive.com>
Subject: Re: [sw-dev] SBI extension proposal v2
Date: Tue, 29 Jan 2019 16:17:20 -0800	[thread overview]
Message-ID: <CAP6exYJT4dqz6uG=RnLh0UhoE9JULE2me9Abjpv2En41r75B0g@mail.gmail.com> (raw)
In-Reply-To: <CAPweEDwAGgTco1bhNqXVj1xxNMFespjSkTxe2DgcACkbTivAoQ@mail.gmail.com>

btw, w.r.t. carrying sbi with the kernel image.

When you get to a big enough world, and you get enough machines,
updating flash to update firmware runtime services is not guaranteed
to end well.
Flash just isn't that great and the less you depend on it the better.

So the idea of being able to fix an SBI problem by kexec'ing a kernel
that carries its own SBI is a very attractive idea. Anything that
reduces the role of persistent memory
for startup is a very attractive idea.

And this is why I believe an M mode that is changeable by the kernel
is a feature, not a bug: it let us do something we could not do
before.

That doesn't mean it is for every possible use; but the fact that you
can do it is great. You can't do that stuff on x86, for example, and
it's been a problem for 25 years now.
This is why I find riscv so attractive, it can free us from old thinking.

On Tue, Jan 29, 2019 at 4:06 PM Luke Kenneth Casson Leighton
<lkcl@lkcl.net> wrote:
>
> ---
> crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
>
> On Tue, Jan 29, 2019 at 11:26 PM Palmer Dabbelt <palmer@sifive.com> wrote:
>
> > Yep, and the hope here is that we can build something that allows everyone to implement their systems within the same framework.  With any luck we'll be able to build a platform specification that allows both of these systems to exist -- essentially "boot Linux into M-mode" or "boot Linux into S-mode".  It'll be work to make sure the spec can work for everyone, but that's part of the way to get a good spec.
>
>  ... and how is that to be achieved if the RISC-V Foundation
> pathologically insists on secretive closed-doors discussions when it
> comes to RISC-V specifications?
>
>  it's time for the RISC-V Foundation to recognise that the ITU-style
> closed doors practice is damaging the ecosystem by preventing people
> from contributing.
>
> l.

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv