Procedures adding new CPUs in sbsa-ref

Procedures adding new CPUs in sbsa-ref

[Itaru Kitayama]

Hi,
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.

Thanks,
Itaru.

Re: Procedures adding new CPUs in sbsa-ref

[Peter Maydell]

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

Re: Procedures adding new CPUs in sbsa-ref

[Itaru Kitayama]

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. Also, the 'max'
is there, but does not boot.

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

Re: Procedures adding new CPUs in sbsa-ref

[Alex Bennée]

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. 

> 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

Re: Procedures adding new CPUs in sbsa-ref

[Itaru Kitayama]

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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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