linux-kernel - [RFT PATCH v1 0/4] Unify CPU topology across ARM64 & RISC-V

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Date:   Thu, 29 Nov 2018 15:28:16 -0800
From:   Atish Patra <atish.patra@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Atish Patra <atish.patra@....com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Anup Patel <anup@...infault.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        devicetree@...r.kernel.org,
        Dmitriy Cherkasov <dmitriy@...-tech.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Jeremy Linton <jeremy.linton@....com>,
        Juri Lelli <juri.lelli@....com>,
        linux-arm-kernel@...ts.infradead.org (moderated list:ARM64 PORT
        (AARCH64 ARCHITECTURE)), linux-riscv@...ts.infradead.org,
        Mark Rutland <mark.rutland@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Palmer Dabbelt <palmer@...ive.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will.deacon@....com>
Subject: [RFT PATCH v1 0/4] Unify CPU topology across ARM64 & RISC-V

The cpu-map DT entry in ARM64 can describe the CPU topology in
much better way compared to other existing approaches. RISC-V can
easily adopt this binding to represent it's own CPU topology.
Thus, both cpu-map DT binding and topology parsing code can be
moved to a common location so that RISC-V or any other
architecture can leverage that.

The relevant discussion regarding unifying cpu topology can be
found in [1].

arch_topology seems to be a perfect place to move the common
code. I have not introduced any functional changes in the moved
code. The only downside in this approach is that the capacity
code will be executed for RISC-V as well. But, it will exit
immediately after not able to find the appropriate DT node. If
the overhead is considered too much, we can always compile out
capacity related functions under a different config for the
architectures that do not support them.

The patches have been tested for RISC-V and compile tested for
ARM64 & x86.

The socket change[2] is also now part of this series.

[1] https://lkml.org/lkml/2018/11/6/19
[2] https://lkml.org/lkml/2018/11/7/918

QEMU changes for RISC-V topology are available at

https://github.com/atishp04/riscv-qemu/tree/cpu_topo

Apologies for the previous patch series with incorrect title and
was sent only to kernel mailing list due to a bug in my config.
Please ignore that.

Atish Patra (3):
dt-binding: cpu-topology: Move cpu-map to a common binding.
cpu-topology: Move cpu topology code to common code.
RISC-V: Parse cpu topology during boot.

Sudeep Holla (1):
Documentation: DT: arm: add support for sockets defining package
boundaries

.../{arm/topology.txt => cpu/cpu-topology.txt}     | 133 +++++++--
arch/arm64/include/asm/topology.h                  |  22 --
arch/arm64/kernel/topology.c                       | 303 +--------------------
arch/riscv/Kconfig                                 |   1 +
arch/riscv/kernel/smpboot.c                        |   3 +
drivers/base/arch_topology.c                       | 294 ++++++++++++++++++++
include/linux/arch_topology.h                      |  26 ++
include/linux/topology.h                           |   1 +
8 files changed, 435 insertions(+), 348 deletions(-)
rename Documentation/devicetree/bindings/{arm/topology.txt => cpu/cpu-topology.txt} (66%)

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2.7.4