Re: [PATCH v7 2/4] dt-bindings: riscv: Add Svade and Svadu Entries

[Alexandre Ghiti <alex@ghiti.fr>]

On 12/07/2024 10:38, Yong-Xuan Wang wrote:
> Add entries for the Svade and Svadu extensions to the riscv,isa-extensions
> property.
>
> Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
> ---
>   .../devicetree/bindings/riscv/extensions.yaml | 28 +++++++++++++++++++
>   1 file changed, 28 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml
> index 468c646247aa..e91a6f4ede38 100644
> --- a/Documentation/devicetree/bindings/riscv/extensions.yaml
> +++ b/Documentation/devicetree/bindings/riscv/extensions.yaml
> @@ -153,6 +153,34 @@ properties:
>               ratified at commit 3f9ed34 ("Add ability to manually trigger
>               workflow. (#2)") of riscv-time-compare.
>   
> +        - const: svade
> +          description: |
> +            The standard Svade supervisor-level extension for SW-managed PTE A/D
> +            bit updates as ratified in the 20240213 version of the privileged
> +            ISA specification.
> +
> +            Both Svade and Svadu extensions control the hardware behavior when
> +            the PTE A/D bits need to be set. The default behavior for the four
> +            possible combinations of these extensions in the device tree are:
> +            1) Neither Svade nor Svadu present in DT => It is technically
> +               unknown whether the platform uses Svade or Svadu. Supervisor
> +               software should be prepared to handle either hardware updating
> +               of the PTE A/D bits or page faults when they need updated.
> +            2) Only Svade present in DT => Supervisor must assume Svade to be
> +               always enabled.
> +            3) Only Svadu present in DT => Supervisor must assume Svadu to be
> +               always enabled.
> +            4) Both Svade and Svadu present in DT => Supervisor must assume
> +               Svadu turned-off at boot time. To use Svadu, supervisor must
> +               explicitly enable it using the SBI FWFT extension.
> +
> +        - const: svadu
> +          description: |
> +            The standard Svadu supervisor-level extension for hardware updating
> +            of PTE A/D bits as ratified at commit c1abccf ("Merge pull request
> +            #25 from ved-rivos/ratified") of riscv-svadu. Please refer to Svade
> +            dt-binding description for more details.
> +
>           - const: svinval
>             description:
>               The standard Svinval supervisor-level extension for fine-grained


Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks,

Alex