[U-Boot] [PATCH v2 1/3] riscv: Add kconfig option to run u-boot in S-mode

[Bin Meng]

Hi Anup,

On Tue, Nov 20, 2018 at 7:29 PM Anup Patel <anup at brainfault.org> wrote:
>
> This patch adds kconfig option RISCV_SMODE to run u-boot in
> S-mode. When this opition is enabled we use s<xyz> CSRs instead
> of m<xyz> CSRs.
>
> It is important to note that there is no equivalent S-mode CSR
> for misa and mhartid CSRs so we expect M-mode runtime firmware
> (BBL or equivalent) to emulate misa and mhartid CSR read.
>
> Eventually, we will have patches to avoid accessing misa and
> mhartid from S-mode.
>

What patches?

> Signed-off-by: Anup Patel <anup at brainfault.org>
> ---
>  arch/riscv/Kconfig     |  6 ++++++
>  arch/riscv/cpu/start.S | 33 +++++++++++++++++++++++++++++++++
>  2 files changed, 39 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 3e0af55e71..88bc0d2a43 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -55,6 +55,12 @@ config RISCV_ISA_C
>  config RISCV_ISA_A
>         def_bool y
>
> +config RISCV_SMODE
> +       bool "Run in S-Mode"
> +       default n

nits: 'default n' is not needed

> +       help
> +         Enable this option to build an U-Boot for RISC-V S-Mode
> +
>  config 32BIT
>         bool
>

[snip]

Other than that,

Reviewed-by: Bin Meng <bmeng.cn at gmail.com>
Tested-by: Bin Meng <bmeng.cn at gmail.com>

Regards,
Bin