linux-kernel - Re: [PATCH v2 04/12] arm64: docs: cpu-feature-registers: Document ID_AA64PFR1

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Message-ID: <87zhi7l8qz.fsf@linaro.org>
Date:   Fri, 11 Oct 2019 14:19:48 +0100
From:   Alex Bennée <alex.bennee@...aro.org>
To:     Dave Martin <Dave.Martin@....com>
Cc:     linux-kernel@...r.kernel.org, Andrew Jones <drjones@...hat.com>,
        Arnd Bergmann <arnd@...db.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Eugene Syromiatnikov <esyr@...hat.com>,
        Florian Weimer <fweimer@...hat.com>,
        "H.J. Lu" <hjl.tools@...il.com>, Jann Horn <jannh@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Kristina Martšenko <kristina.martsenko@....com>,
        Mark Brown <broonie@...nel.org>,
        Paul Elliott <paul.elliott@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Richard Henderson <richard.henderson@...aro.org>,
        Sudakshina Das <sudi.das@....com>,
        Szabolcs Nagy <szabolcs.nagy@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will.deacon@....com>,
        Yu-cheng Yu <yu-cheng.yu@...el.com>,
        Amit Kachhap <amit.kachhap@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 04/12] arm64: docs: cpu-feature-registers: Document
 ID_AA64PFR1_EL1


Dave Martin <Dave.Martin@....com> writes:

> Commit d71be2b6c0e1 ("arm64: cpufeature: Detect SSBS and advertise
> to userspace") exposes ID_AA64PFR1_EL1 to userspace, but didn't
> update the documentation to match.
>
> Add it.
>
> Signed-off-by: Dave Martin <Dave.Martin@....com>
>
> ---
>
> Note to maintainers:
>
>  * This patch has been racing with various other attempts to fix
>    the same documentation in the meantime.
>
>    Since this patch only fixes the documenting for pre-existing
>    features, it can safely be dropped if appropriate.
>
>    The _new_ documentation relating to BTI feature reporting
>    is in a subsequent patch, and needs to be retained.
> ---
>  Documentation/arm64/cpu-feature-registers.rst | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/arm64/cpu-feature-registers.rst b/Documentation/arm64/cpu-feature-registers.rst
> index 2955287..b86828f 100644
> --- a/Documentation/arm64/cpu-feature-registers.rst
> +++ b/Documentation/arm64/cpu-feature-registers.rst
> @@ -168,8 +168,15 @@ infrastructure:
>       +------------------------------+---------+---------+
>
>
> -  3) MIDR_EL1 - Main ID Register
> +  3) ID_AA64PFR1_EL1 - Processor Feature Register 1
> +     +------------------------------+---------+---------+
> +     | Name                         |  bits   | visible |
> +     +------------------------------+---------+---------+
> +     | SSBS                         | [7-4]   |    y    |
> +     +------------------------------+---------+---------+
> +
>
> +  4) MIDR_EL1 - Main ID Register
>       +------------------------------+---------+---------+
>       | Name                         |  bits   | visible |
>       +------------------------------+---------+---------+
> @@ -188,7 +195,7 @@ infrastructure:
>     as available on the CPU where it is fetched and is not a system
>     wide safe value.
>
> -  4) ID_AA64ISAR1_EL1 - Instruction set attribute register 1
> +  5) ID_AA64ISAR1_EL1 - Instruction set attribute register 1

If I'm not mistaken .rst has support for auto-enumeration if the #
character is used. That might reduce the pain of re-numbering in future.

>
>       +------------------------------+---------+---------+
>       | Name                         |  bits   | visible |
> @@ -210,7 +217,7 @@ infrastructure:
>       | DPB                          | [3-0]   |    y    |
>       +------------------------------+---------+---------+
>
> -  5) ID_AA64MMFR2_EL1 - Memory model feature register 2
> +  6) ID_AA64MMFR2_EL1 - Memory model feature register 2
>
>       +------------------------------+---------+---------+
>       | Name                         |  bits   | visible |
> @@ -218,7 +225,7 @@ infrastructure:
>       | AT                           | [35-32] |    y    |
>       +------------------------------+---------+---------+
>
> -  6) ID_AA64ZFR0_EL1 - SVE feature ID register 0
> +  7) ID_AA64ZFR0_EL1 - SVE feature ID register 0
>
>       +------------------------------+---------+---------+
>       | Name                         |  bits   | visible |


--
Alex Bennée