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From:   Guo Ren <guoren@kernel.org>
Date:   Sun, 31 May 2020 08:58:18 +0800
Message-ID: <CAJF2gTTdyXybMGPzqKi1Z_ueQkf5XxiZK2X1HrDnZkCaVU1DAg@mail.gmail.com>
Subject: Re: [RFC PATCH v4 07/13] riscv: Add has_vector/riscv_vsize to save
 vector features.
To:     Greentime Hu <greentime.hu@sifive.com>
Cc:     Guo Ren <guoren@linux.alibaba.com>,
        Vincent Chen <vincent.chen@sifive.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        palmerdabbelt@google.com,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        oleg@redhat.com
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Reviewed-by: Guo Ren <guoren@kernel.org>

On Tue, May 26, 2020 at 3:03 PM Greentime Hu <greentime.hu@sifive.com> wrote:
>
> From: Guo Ren <guoren@linux.alibaba.com>
>
> This patch is used to detect vector support status of CPU and use
> riscv_vsize to save the size of all the vector registers. It assumes
> all harts has the same capabilities in SMP system.
>
> [greentime.hu@sifive.com: add support for dynamic vlen]
> Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> ---
>  arch/riscv/kernel/cpufeature.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index c8527d770c98..5a68a926da68 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -16,6 +16,10 @@ unsigned long elf_hwcap __read_mostly;
>  #ifdef CONFIG_FPU
>  bool has_fpu __read_mostly;
>  #endif
> +#ifdef CONFIG_VECTOR
> +bool has_vector __read_mostly;
> +unsigned long riscv_vsize __read_mostly;
> +#endif
>
>  void riscv_fill_hwcap(void)
>  {
> @@ -73,4 +77,11 @@ void riscv_fill_hwcap(void)
>         if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
>                 has_fpu = true;
>  #endif
> +
> +#ifdef CONFIG_VECTOR
> +       if (elf_hwcap & COMPAT_HWCAP_ISA_V) {
> +               has_vector = true;
> +               riscv_vsize = csr_read(CSR_VLENB) * 32;
No magic number 32.
eg:
#define VECTOR_REGS_NUM 32

-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/