linux-kernel - Re: [PATCH] arm64: topology: Stop using MPIDR for topology information

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Message-Id: <159951413581.3126645.5011278165801551941.b4-ty@kernel.org>
Date:   Mon,  7 Sep 2020 22:35:35 +0100
From:   Will Deacon <will@...nel.org>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Valentin Schneider <valentin.schneider@....com>
Cc:     catalin.marinas@....com, kernel-team@...roid.com,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        "Zengtao (B)" <prime.zeng@...ilicon.com>,
        Sudeep Holla <sudeep.holla@....com>,
        Jeremy Linton <Jeremy.Linton@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>
Subject: Re: [PATCH] arm64: topology: Stop using MPIDR for topology information

On Sat, 29 Aug 2020 14:00:16 +0100, Valentin Schneider wrote:
> In the absence of ACPI or DT topology data, we fallback to haphazardly
> decoding *something* out of MPIDR. Sadly, the contents of that register are
> mostly unusable due to the implementation leniancy and things like Aff0
> having to be capped to 15 (despite being encoded on 8 bits).
> 
> Consider a simple system with a single package of 32 cores, all under the
> same LLC. We ought to be shoving them in the same core_sibling mask, but
> MPIDR is going to look like:
> 
> [...]

Applied to arm64 (for-next/topology), thanks!

[1/1] arm64: topology: Stop using MPIDR for topology information
      https://git.kernel.org/arm64/c/3102bc0e6ac7

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev