linux-kernel - Re: [PATCH v6 0/6] Provide a fraemework for RISC-V ISA extensions

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Message-ID: <mhng-596cc82d-51af-448c-bd04-51b517fe79c7@palmer-ri-x1c9>
Date:   Thu, 17 Mar 2022 20:10:05 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     Atish Patra <atishp@...osinc.com>
CC:     linux-kernel@...r.kernel.org, Atish Patra <atishp@...osinc.com>,
        aou@...s.berkeley.edu, atishp@...shpatra.org, anup@...infault.org,
        damien.lemoal@....com, devicetree@...r.kernel.org,
        jszhang@...nel.org, krzysztof.kozlowski@...onical.com,
        linux-riscv@...ts.infradead.org,
        Paul Walmsley <paul.walmsley@...ive.com>, robh+dt@...nel.org
Subject:     Re: [PATCH v6 0/6] Provide a fraemework for RISC-V ISA extensions 

On Mon, 14 Mar 2022 13:38:39 PDT (-0700), Atish Patra wrote:
> This series implements a generic framework to parse multi-letter ISA
> extensions. This series is based on Tsukasa's v3 isa extension improvement
> series[1]. I have fixed few bugs and improved comments from that series
> (PATCH1-3). I have not used PATCH 4 from that series as we are not using
> ISA extension versioning as of now. We can add that later if required.
>
> PATCH 4 allows the probing of multi-letter extensions via a macro.
> It continues to use the common isa extensions between all the harts.
> Thus hetergenous hart systems will only see the common ISA extensions.
>
> PATCH 6 improves the /proc/cpuinfo interface for the available ISA extensions
> via /proc/cpuinfo.
>
> Here is the example output of /proc/cpuinfo:
> (with debug patches in Qemu and Linux kernel)
>
> / # cat /proc/cpuinfo
> processor	: 0
> hart		: 0
> isa		: rv64imafdch_svpbmt_svnapot_svinval
> mmu		: sv48
>
> processor	: 1
> hart		: 1
> isa		: rv64imafdch_svpbmt_svnapot_svinval
> mmu		: sv48
>
> processor	: 2
> hart		: 2
> isa		: rv64imafdch_svpbmt_svnapot_svinval
> mmu		: sv48
>
> processor	: 3
> hart		: 3
> isa		: rv64imafdch_svpbmt_svnapot_svinval
> mmu		: sv48
>
> Anybody adding support for any new multi-letter extensions should add an
> entry to the riscv_isa_ext_id and the isa extension array.
> E.g. The patch[2] adds the support for various ISA extensions.
>
> [1] https://lore.kernel.org/all/0f568515-a05e-8204-aae3-035975af3ee8@irq.a4lg.com/T/
> [2] https://github.com/atishp04/linux/commit/e9e240c9a854dceb434ceb53bdbe82a657bee5f2
>
> Changes from v5->v6:
> 1. Changed the isa extension format from separate row to single row that follows
>    RISC-V spec naming standards.
>
> 2. Removed the redundant extension detection log.
>
> Changes from v4->v5:
> 1. Improved the /proc/cpuinfo to include only valid & enabled extensions
> 2. Improved the multi-letter parsing by skipping the 'su' modes generated in
>    Qemu as suggested by Tsukasa.
>
> Changes from v3->v4:
> 1. Changed temporary variable for current hart isa to a bitmap
> 2. Added reviewed-by tags.
> 3. Improved comments
>
> Changes from v2->v3:
> 1. Updated comments to mark clearly a fix required for Qemu only.
> 2. Fixed a bug where the 1st multi-letter extension can be present without _
> 3. Added Tested by tags.
>
> Changes from v1->v2:
> 1. Instead of adding a separate DT property use the riscv,isa property.
> 2. Based on Tsukasa's v3 isa extension improvement series.
>
> Atish Patra (3):
> RISC-V: Implement multi-letter ISA extension probing framework
> RISC-V: Do no continue isa string parsing without correct XLEN
> RISC-V: Improve /proc/cpuinfo output for ISA extensions
>
> Tsukasa OI (3):
> RISC-V: Correctly print supported extensions
> RISC-V: Minimal parser for "riscv, isa" strings
> RISC-V: Extract multi-letter extension names from "riscv, isa"
>
> arch/riscv/include/asm/hwcap.h |  25 +++++++
> arch/riscv/kernel/cpu.c        |  65 ++++++++++++++++-
> arch/riscv/kernel/cpufeature.c | 128 +++++++++++++++++++++++++++------
> 3 files changed, 195 insertions(+), 23 deletions(-)

Thanks, this is on for-next.