Re: Procedures adding new CPUs in sbsa-ref

[Itaru Kitayama <itaru.kitayama@gmail.com>]

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On Tue, Apr 12, 2022 at 0:22 Alex Bennée <alex.bennee@linaro.org> wrote:

>
> Itaru Kitayama <itaru.kitayama@gmail.com> writes:
>
> > Good point; however per the SBSA specification, DEN0029F, there's the
> > PE architecture requirement at
> > each level from 1 to 7, so now I am wondering whether supporting
> > cortex-a57 and a72 are good enough to
> > set up a fully SBSA level 7 compliant "board" in QMEU.
>
> Not currently - we are working on cortex-a76/neoverse-n1 which will
> provide a v8.2 baseline for sbsa-ref. See:
>
>   Subject: [PATCH 00/16] target/arm: Implement features Debugv8p4, RAS,
> IESB
>   Date: Fri,  8 Apr 2022 17:07:26 -0700
>   Message-Id: <20220409000742.293691-1-richard.henderson@linaro.org>
>
> and:
>
>   Subject: [PATCH 0/7] target/arm: More trivial features, A76, N1
>   Date: Sat,  9 Apr 2022 22:57:18 -0700
>   Message-Id: <20220410055725.380246-1-richard.henderson@linaro.org>
>
> which are stepping stones to those concrete models. Please review if you
> can.


Sure, Shuichi and I will review Richard’s series and give feedback if
there’s any.

Itaru.


>
> > Also, the 'max'
> > is there, but does not boot.
>
> Generally the firmware has to be built with the knowledge of what system
> it is running on so will generally fall over if run on a different CPU
> feature set. However I believe Leif had a firmware branch which attempts
> to work with -cpu max by doing proper ID register probing before using
> features. However -cpu max is very a moving feast which is why there is
> a push for the concrete CPU types.
>
> I believe there is a proposal for a versioned sbsa-ref model which will
> step of the default CPU for higher levels.
>
> >
> > Itaru.
> >
> > On Sat, Apr 9, 2022 at 12:04 AM Peter Maydell <peter.maydell@linaro.org>
> wrote:
> >>
> >> On Fri, 8 Apr 2022 at 15:59, Itaru Kitayama <itaru.kitayama@gmail.com>
> wrote:
> >> > I'd like to add a64fx cpu to the sbsa-ref board, if there's a quick
> and dirty
> >> > way of completing that, advice from the  maintainers is greatly
> appreciated.
> >>
> >> I have cc'd the sbsa-ref maintainers (as listed in the MAINTAINERS
> file).
> >>
> >> However, I'm not sure why you want to add the a64fx CPU to this
> >> board model? The sbsa-ref board is intended as a platform for
> >> developing firmware that runs on Server Base System Architecture
> >> hardware, so it deliberately doesn't have support for every CPU
> >> type QEMU implements.
> >>
> >> thanks
> >> -- PMM
>
>
> --
> Alex Bennée
>

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