Re: [RFC PATCH v4 07/13] riscv: Add has_vector/riscv_vsize to save vector features.

[Guo Ren]

Reviewed-by: Guo Ren <guoren@xxxxxxxxxx>

On Tue, May 26, 2020 at 3:03 PM Greentime Hu <greentime.hu@xxxxxxxxxx> wrote:
>
> From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
>
> 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@xxxxxxxxxx: add support for dynamic vlen]
> Signed-off-by: Greentime Hu <greentime.hu@xxxxxxxxxx>
> Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
> ---
>  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/