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Date:   Mon, 20 Nov 2017 08:35:28 +0100
From:   Jonathan =?utf-8?Q?Neusch=C3=A4fer?= <j.neuschaefer@gmx.net>
To:     patches@groups.riscv.org
Cc:     Palmer Dabbelt <palmer@dabbelt.com>, Arnd Bergmann <arnd@arndb.de>,
        sfr@canb.auug.org.au, Olof Johansson <olof@lixom.net>,
        linux-kernel@vger.kernel.org, robh+dt@kernel.org,
        albert@sifive.com, yamada.masahiro@socionext.com, mmarek@suse.com,
        will.deacon@arm.com, peterz@infradead.org, boqun.feng@gmail.com,
        oleg@redhat.com, mingo@redhat.com, devicetree@vger.kernel.org,
        ron minnich <rminnich@gmail.com>
Subject: Re: [patches] Re: [PATCH v9 03/12] dt-bindings: RISC-V CPU Bindings
Message-ID: <20171120073528.xkv4cydyniuhzshf@latitude>
References: <20170927015638.19443-1-palmer@dabbelt.com>
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Hi Palmer,

On Thu, Oct 05, 2017 at 11:16:33AM +0100, Mark Rutland wrote:
[...]
> I would *strongly* recommend that from day one, you determine the SMP
> bringup mechanism via an enable-method property, and document the
> contract with FW/bootloader somewhere in the kernel tree.

Somewhat, but not quite related: Please consider making the availability
of the Supervisor Binary Interface explicit in the devicetree.
I understand that the general plan is to make the SBI a mandatory
feature of every RISC-V system capable of running Linux, but I do want
to explore the possibility of running without run-time resident firmware
at some point in the future. Thus it would be nice if the devicetree
would indicate the presence of the SBI from the start, to avoid having
to invent a way to express its *absence* later on.

It could look something like this (modelled after qcom,scm):

/ {
	firmware {
		sbi {
			compatible =3D "riscv,sbi";
		};
	};
};

This topic may warrant some discussion, because other people may have
different opinions, and there hasn't been a discussion about it, AFAICS.


Thanks,
Jonathan Neusch=C3=A4fer

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