[U-Boot] [PATCH 06/30] riscv: add Kconfig entries for the C and A ISA extensions

[Bin Meng]

Hi Lukas,

On Sat, Oct 20, 2018 at 6:09 AM Lukas Auer
<lukas.auer at aisec.fraunhofer.de> wrote:
>
> Add Kconfig entries for the C (compressed instructions) and A (atomic
> instructions) ISA extensions. Only the C ISA extension is selectable.
> This matches the configuration in Linux.
>
> The Kconfig entries are not used yet. A follow-up patch will select the
> appropriate compiler flags based on the Kconfig configuration.
>
> Signed-off-by: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
> ---
>
>  arch/riscv/Kconfig | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index b81e0d990a..e15329c35e 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -38,6 +38,15 @@ config ARCH_RV64I
>
>  endchoice
>
> +config RISCV_ISA_C
> +       bool "Emit compressed instructions"
> +       default y
> +       help
> +         This enables the compressed instructions ("C") ISA extension.

This is a little bit confusing. Can we use Linux kernel's description
instead like below?

          Adds "C" to the ISA subsets that the toolchain is allowed to emit
          when building U-Boot, which results in compressed instructions in the
          U-Boot binary.

> +
> +config RISCV_ISA_A
> +       def_bool y

I do not believe U-Boot need to care about 'A' extension. So this can
be dropped?

> +
>  config 32BIT
>         bool
>

Regards,
Bin