linux-kernel - Re: [PATCH V2 3/4] riscv: Extending cpufeature.c to detect V-extension

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Date:   Thu, 23 Jan 2020 11:15:09 +0530
From:   Anup Patel <anup@...infault.org>
To:     Guo Ren <guoren@...nel.org>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Anup Patel <Anup.Patel@....com>,
        Vincent Chen <vincent.chen@...ive.com>,
        Zong Li <zong.li@...ive.com>,
        Greentime Hu <greentime.hu@...ive.com>,
        Bin Meng <bmeng.cn@...il.com>,
        Atish Patra <atish.patra@....com>,
        Andreas Schwab <schwab@...ux-m68k.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        linux-arch@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        linux-csky@...r.kernel.org,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Guo Ren <ren_guo@...ky.com>
Subject: Re: [PATCH V2 3/4] riscv: Extending cpufeature.c to detect V-extension

On Thu, Jan 16, 2020 at 8:01 PM <guoren@...nel.org> wrote:
>
> From: Guo Ren <ren_guo@...ky.com>
>
> Current cpufeature.c doesn't support detecting V-extension, because
> "rv64" also contain a 'v' letter and we need to skip it.
>
> Signed-off-by: Guo Ren <ren_guo@...ky.com>
> Cc: Anup Patel <Anup.Patel@....com>
> ---
>  arch/riscv/include/uapi/asm/hwcap.h | 1 +
>  arch/riscv/kernel/cpufeature.c      | 4 +++-
>  2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/include/uapi/asm/hwcap.h b/arch/riscv/include/uapi/asm/hwcap.h
> index dee98ee28318..a913e9a38819 100644
> --- a/arch/riscv/include/uapi/asm/hwcap.h
> +++ b/arch/riscv/include/uapi/asm/hwcap.h
> @@ -21,5 +21,6 @@
>  #define COMPAT_HWCAP_ISA_F     (1 << ('F' - 'A'))
>  #define COMPAT_HWCAP_ISA_D     (1 << ('D' - 'A'))
>  #define COMPAT_HWCAP_ISA_C     (1 << ('C' - 'A'))
> +#define COMPAT_HWCAP_ISA_V     (1 << ('V' - 'A'))
>
>  #endif /* _UAPI_ASM_RISCV_HWCAP_H */
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index a5ad00043104..c8527d770c98 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -30,6 +30,7 @@ void riscv_fill_hwcap(void)
>         isa2hwcap['f'] = isa2hwcap['F'] = COMPAT_HWCAP_ISA_F;
>         isa2hwcap['d'] = isa2hwcap['D'] = COMPAT_HWCAP_ISA_D;
>         isa2hwcap['c'] = isa2hwcap['C'] = COMPAT_HWCAP_ISA_C;
> +       isa2hwcap['v'] = isa2hwcap['V'] = COMPAT_HWCAP_ISA_V;
>
>         elf_hwcap = 0;
>
> @@ -44,7 +45,8 @@ void riscv_fill_hwcap(void)
>                         continue;
>                 }
>
> -               for (i = 0; i < strlen(isa); ++i)
> +               /* Skip rv64/rv32 to support v/V:vector */
> +               for (i = 4; i < strlen(isa); ++i)
>                         this_hwcap |= isa2hwcap[(unsigned char)(isa[i])];
>
>                 /*
> --
> 2.17.0
>

LGTM.

Reviewed-by: Anup Patel <anup@...infault.org>

Regards,
Anup